Jesse Barnes Initial version Intel Corporation

jesse.barnes@intel.com

Laurent Pinchart Driver internals Ideas on board SPRL

laurent.pinchart@ideasonboard.com

Daniel Vetter Contributions all over the place Intel Corporation

daniel.vetter@ffwll.ch

2008-2009 2013-2014 Intel Corporation 2012 Laurent Pinchart The contents of this file may be used under the terms of the GNU General Public License version 2 (the "GPL") as distributed in the kernel source COPYING file. 1.0 2012-07-13 LP Added extensive documentation about driver internals. This first part of the DRM Developer's Guide documents core DRM code, helper libraries for writing drivers and generic userspace interfaces exposed by DRM drivers. The Linux DRM layer contains code intended to support the needs of complex graphics devices, usually containing programmable pipelines well suited to 3D graphics acceleration. Graphics drivers in the kernel may make use of DRM functions to make tasks like memory management, interrupt handling and DMA easier, and provide a uniform interface to applications. A note on versions: this guide covers features found in the DRM tree, including the TTM memory manager, output configuration and mode setting, and the new vblank internals, in addition to all the regular features found in current kernels. [Insert diagram of typical DRM stack here] This chapter documents DRM internals relevant to driver authors and developers working to add support for the latest features to existing drivers. First, we go over some typical driver initialization requirements, like setting up command buffers, creating an initial output configuration, and initializing core services. Subsequent sections cover core internals in more detail, providing implementation notes and examples. The DRM layer provides several services to graphics drivers, many of them driven by the application interfaces it provides through libdrm, the library that wraps most of the DRM ioctls. These include vblank event handling, memory management, output management, framebuffer management, command submission & fencing, suspend/resume support, and DMA services. At the core of every DRM driver is a drm_driver structure. Drivers typically statically initialize a drm_driver structure, and then pass it to one of the drm_*_init() functions to register it with the DRM subsystem. Newer drivers that no longer require a drm_bus structure can alternatively use the low-level device initialization and registration functions such as drm_dev_alloc() and drm_dev_register() directly. The drm_driver structure contains static information that describes the driver and features it supports, and pointers to methods that the DRM core will call to implement the DRM API. We will first go through the drm_driver static information fields, and will then describe individual operations in details as they get used in later sections. Drivers inform the DRM core about their requirements and supported features by setting appropriate flags in the driver_features field. Since those flags influence the DRM core behaviour since registration time, most of them must be set to registering the drm_driver instance. u32 driver_features; DRIVER_USE_AGP Driver uses AGP interface, the DRM core will manage AGP resources. DRIVER_REQUIRE_AGP Driver needs AGP interface to function. AGP initialization failure will become a fatal error. DRIVER_PCI_DMA Driver is capable of PCI DMA, mapping of PCI DMA buffers to userspace will be enabled. Deprecated. DRIVER_SG Driver can perform scatter/gather DMA, allocation and mapping of scatter/gather buffers will be enabled. Deprecated. DRIVER_HAVE_DMA Driver supports DMA, the userspace DMA API will be supported. Deprecated. DRIVER_HAVE_IRQDRIVER_IRQ_SHARED DRIVER_HAVE_IRQ indicates whether the driver has an IRQ handler managed by the DRM Core. The core will support simple IRQ handler installation when the flag is set. The installation process is described in . DRIVER_IRQ_SHARED indicates whether the device & handler support shared IRQs (note that this is required of PCI drivers). DRIVER_GEM Driver use the GEM memory manager. DRIVER_MODESET Driver supports mode setting interfaces (KMS). DRIVER_PRIME Driver implements DRM PRIME buffer sharing. DRIVER_RENDER Driver supports dedicated render nodes. DRIVER_ATOMIC Driver supports atomic properties. In this case the driver must implement appropriate obj->atomic_get_property() vfuncs for any modeset objects with driver specific properties. int major; int minor; int patchlevel; The DRM core identifies driver versions by a major, minor and patch level triplet. The information is printed to the kernel log at initialization time and passed to userspace through the DRM_IOCTL_VERSION ioctl. The major and minor numbers are also used to verify the requested driver API version passed to DRM_IOCTL_SET_VERSION. When the driver API changes between minor versions, applications can call DRM_IOCTL_SET_VERSION to select a specific version of the API. If the requested major isn't equal to the driver major, or the requested minor is larger than the driver minor, the DRM_IOCTL_SET_VERSION call will return an error. Otherwise the driver's set_version() method will be called with the requested version. char *name; char *desc; char *date; The driver name is printed to the kernel log at initialization time, used for IRQ registration and passed to userspace through DRM_IOCTL_VERSION. The driver description is a purely informative string passed to userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by the kernel. The driver date, formatted as YYYYMMDD, is meant to identify the date of the latest modification to the driver. However, as most drivers fail to update it, its value is mostly useless. The DRM core prints it to the kernel log at initialization time and passes it to userspace through the DRM_IOCTL_VERSION ioctl. A number of functions are provided to help with device registration. The functions deal with PCI and platform devices, respectively. Kernel Hackers Manual July 2017 drm_pci_alloc 9 4.1.27 drm_pci_alloc Allocate a PCI consistent memory block, for DMA. drm_dma_handle_t * drm_pci_alloc struct drm_device * dev size_t size size_t align dev DRM device size size of block to allocate align alignment of block A handle to the allocated memory block on success or NULL on failure. Kernel Hackers Manual July 2017 drm_pci_free 9 4.1.27 drm_pci_free Free a PCI consistent memory block void drm_pci_free struct drm_device * dev drm_dma_handle_t * dmah dev DRM device dmah handle to memory block Kernel Hackers Manual July 2017 drm_get_pci_dev 9 4.1.27 drm_get_pci_dev Register a PCI device with the DRM subsystem int drm_get_pci_dev struct pci_dev * pdev const struct pci_device_id * ent struct drm_driver * driver pdev PCI device ent entry from the PCI ID table that matches pdev driver DRM device driver Attempt to gets inter module drm information. If we are first then register the character device and inter module information. Try and register, if we fail to register, backout previous work. 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_pci_init 9 4.1.27 drm_pci_init Register matching PCI devices with the DRM subsystem int drm_pci_init struct drm_driver * driver struct pci_driver * pdriver driver DRM device driver pdriver PCI device driver Initializes a drm_device structures, registering the stubs and initializing the AGP device. 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_pci_exit 9 4.1.27 drm_pci_exit Unregister matching PCI devices from the DRM subsystem void drm_pci_exit struct drm_driver * driver struct pci_driver * pdriver driver DRM device driver pdriver PCI device driver Unregisters one or more devices matched by a PCI driver from the DRM subsystem. Kernel Hackers Manual July 2017 drm_platform_init 9 4.1.27 drm_platform_init Register a platform device with the DRM subsystem int drm_platform_init struct drm_driver * driver struct platform_device * platform_device driver DRM device driver platform_device platform device to register Registers the specified DRM device driver and platform device with the DRM subsystem, initializing a drm_device structure and calling the driver's .load function. 0 on success or a negative error code on failure. New drivers that no longer rely on the services provided by the drm_bus structure can call the low-level device registration functions directly. The drm_dev_alloc() function can be used to allocate and initialize a new drm_device structure. Drivers will typically want to perform some additional setup on this structure, such as allocating driver-specific data and storing a pointer to it in the DRM device's dev_private field. Drivers should also set the device's unique name using the drm_dev_set_unique() function. After it has been set up a device can be registered with the DRM subsystem by calling drm_dev_register(). This will cause the device to be exposed to userspace and will call the driver's .load() implementation. When a device is removed, the DRM device can safely be unregistered and freed by calling drm_dev_unregister() followed by a call to drm_dev_unref(). Kernel Hackers Manual July 2017 drm_put_dev 9 4.1.27 drm_put_dev Unregister and release a DRM device void drm_put_dev struct drm_device * dev dev DRM device Called at module unload time or when a PCI device is unplugged. Use of this function is discouraged. It will eventually go away completely. Please use drm_dev_unregister and drm_dev_unref explicitly instead. Cleans up all DRM device, calling drm_lastclose. Kernel Hackers Manual July 2017 drm_dev_alloc 9 4.1.27 drm_dev_alloc Allocate new DRM device struct drm_device * drm_dev_alloc struct drm_driver * driver struct device * parent driver DRM driver to allocate device for parent Parent device object Allocate and initialize a new DRM device. No device registration is done. Call drm_dev_register to advertice the device to user space and register it with other core subsystems. The initial ref-count of the object is 1. Use drm_dev_ref and drm_dev_unref to take and drop further ref-counts. Note that for purely virtual devices parent can be NULL. Pointer to new DRM device, or NULL if out of memory. Kernel Hackers Manual July 2017 drm_dev_ref 9 4.1.27 drm_dev_ref Take reference of a DRM device void drm_dev_ref struct drm_device * dev dev device to take reference of or NULL This increases the ref-count of dev by one. You *must* already own a reference when calling this. Use drm_dev_unref to drop this reference again. This function never fails. However, this function does not provide *any* guarantee whether the device is alive or running. It only provides a reference to the object and the memory associated with it. Kernel Hackers Manual July 2017 drm_dev_unref 9 4.1.27 drm_dev_unref Drop reference of a DRM device void drm_dev_unref struct drm_device * dev dev device to drop reference of or NULL This decreases the ref-count of dev by one. The device is destroyed if the ref-count drops to zero. Kernel Hackers Manual July 2017 drm_dev_register 9 4.1.27 drm_dev_register Register DRM device int drm_dev_register struct drm_device * dev unsigned long flags dev Device to register flags Flags passed to the driver's .load function Register the DRM device dev with the system, advertise device to user-space and start normal device operation. dev must be allocated via drm_dev_alloc previously. Never call this twice on any device! 0 on success, negative error code on failure. Kernel Hackers Manual July 2017 drm_dev_unregister 9 4.1.27 drm_dev_unregister Unregister DRM device void drm_dev_unregister struct drm_device * dev dev Device to unregister Unregister the DRM device from the system. This does the reverse of drm_dev_register but does not deallocate the device. The caller must call drm_dev_unref to drop their final reference. Kernel Hackers Manual July 2017 drm_dev_set_unique 9 4.1.27 drm_dev_set_unique Set the unique name of a DRM device int drm_dev_set_unique struct drm_device * dev const char * fmt ... dev device of which to set the unique name fmt format string for unique name ... variable arguments Sets the unique name of a DRM device using the specified format string and a variable list of arguments. Drivers can use this at driver probe time if the unique name of the devices they drive is static. 0 on success or a negative error code on failure. The load method is the driver and device initialization entry point. The method is responsible for allocating and initializing driver private data, performing resource allocation and mapping (e.g. acquiring clocks, mapping registers or allocating command buffers), initializing the memory manager (), installing the IRQ handler (), setting up vertical blanking handling (), mode setting () and initial output configuration (). If compatibility is a concern (e.g. with drivers converted over from User Mode Setting to Kernel Mode Setting), care must be taken to prevent device initialization and control that is incompatible with currently active userspace drivers. For instance, if user level mode setting drivers are in use, it would be problematic to perform output discovery & configuration at load time. Likewise, if user-level drivers unaware of memory management are in use, memory management and command buffer setup may need to be omitted. These requirements are driver-specific, and care needs to be taken to keep both old and new applications and libraries working. int (*load) (struct drm_device *, unsigned long flags); The method takes two arguments, a pointer to the newly created drm_device and flags. The flags are used to pass the driver_data field of the device id corresponding to the device passed to drm_*_init(). Only PCI devices currently use this, USB and platform DRM drivers have their load method called with flags to 0. The driver private hangs off the main drm_device structure and can be used for tracking various device-specific bits of information, like register offsets, command buffer status, register state for suspend/resume, etc. At load time, a driver may simply allocate one and set drm_device.dev_priv appropriately; it should be freed and drm_device.dev_priv set to NULL when the driver is unloaded. The DRM core tries to facilitate IRQ handler registration and unregistration by providing drm_irq_install and drm_irq_uninstall functions. Those functions only support a single interrupt per device, devices that use more than one IRQs need to be handled manually. drm_irq_install starts by calling the irq_preinstall driver operation. The operation is optional and must make sure that the interrupt will not get fired by clearing all pending interrupt flags or disabling the interrupt. The passed-in IRQ will then be requested by a call to request_irq. If the DRIVER_IRQ_SHARED driver feature flag is set, a shared (IRQF_SHARED) IRQ handler will be requested. The IRQ handler function must be provided as the mandatory irq_handler driver operation. It will get passed directly to request_irq and thus has the same prototype as all IRQ handlers. It will get called with a pointer to the DRM device as the second argument. Finally the function calls the optional irq_postinstall driver operation. The operation usually enables interrupts (excluding the vblank interrupt, which is enabled separately), but drivers may choose to enable/disable interrupts at a different time. drm_irq_uninstall is similarly used to uninstall an IRQ handler. It starts by waking up all processes waiting on a vblank interrupt to make sure they don't hang, and then calls the optional irq_uninstall driver operation. The operation must disable all hardware interrupts. Finally the function frees the IRQ by calling free_irq. Drivers that require multiple interrupt handlers can't use the managed IRQ registration functions. In that case IRQs must be registered and unregistered manually (usually with the request_irq and free_irq functions, or their devm_* equivalent). When manually registering IRQs, drivers must not set the DRIVER_HAVE_IRQ driver feature flag, and must not provide the irq_handler driver operation. They must set the drm_device irq_enabled field to 1 upon registration of the IRQs, and clear it to 0 after unregistering the IRQs. Every DRM driver requires a memory manager which must be initialized at load time. DRM currently contains two memory managers, the Translation Table Manager (TTM) and the Graphics Execution Manager (GEM). This document describes the use of the GEM memory manager only. See for details. Another task that may be necessary for PCI devices during configuration is mapping the video BIOS. On many devices, the VBIOS describes device configuration, LCD panel timings (if any), and contains flags indicating device state. Mapping the BIOS can be done using the pci_map_rom() call, a convenience function that takes care of mapping the actual ROM, whether it has been shadowed into memory (typically at address 0xc0000) or exists on the PCI device in the ROM BAR. Note that after the ROM has been mapped and any necessary information has been extracted, it should be unmapped; on many devices, the ROM address decoder is shared with other BARs, so leaving it mapped could cause undesired behaviour like hangs or memory corruption. Modern Linux systems require large amount of graphics memory to store frame buffers, textures, vertices and other graphics-related data. Given the very dynamic nature of many of that data, managing graphics memory efficiently is thus crucial for the graphics stack and plays a central role in the DRM infrastructure. The DRM core includes two memory managers, namely Translation Table Maps (TTM) and Graphics Execution Manager (GEM). TTM was the first DRM memory manager to be developed and tried to be a one-size-fits-them all solution. It provides a single userspace API to accommodate the need of all hardware, supporting both Unified Memory Architecture (UMA) devices and devices with dedicated video RAM (i.e. most discrete video cards). This resulted in a large, complex piece of code that turned out to be hard to use for driver development. GEM started as an Intel-sponsored project in reaction to TTM's complexity. Its design philosophy is completely different: instead of providing a solution to every graphics memory-related problems, GEM identified common code between drivers and created a support library to share it. GEM has simpler initialization and execution requirements than TTM, but has no video RAM management capabilities and is thus limited to UMA devices. TTM design background and information belongs here. This section is outdated. Drivers wishing to support TTM must fill out a drm_bo_driver structure. The structure contains several fields with function pointers for initializing the TTM, allocating and freeing memory, waiting for command completion and fence synchronization, and memory migration. See the radeon_ttm.c file for an example of usage. The ttm_global_reference structure is made up of several fields: struct ttm_global_reference { enum ttm_global_types global_type; size_t size; void *object; int (*init) (struct ttm_global_reference *); void (*release) (struct ttm_global_reference *); }; There should be one global reference structure for your memory manager as a whole, and there will be others for each object created by the memory manager at runtime. Your global TTM should have a type of TTM_GLOBAL_TTM_MEM. The size field for the global object should be sizeof(struct ttm_mem_global), and the init and release hooks should point at your driver-specific init and release routines, which probably eventually call ttm_mem_global_init and ttm_mem_global_release, respectively. Once your global TTM accounting structure is set up and initialized by calling ttm_global_item_ref() on it, you need to create a buffer object TTM to provide a pool for buffer object allocation by clients and the kernel itself. The type of this object should be TTM_GLOBAL_TTM_BO, and its size should be sizeof(struct ttm_bo_global). Again, driver-specific init and release functions may be provided, likely eventually calling ttm_bo_global_init() and ttm_bo_global_release(), respectively. Also, like the previous object, ttm_global_item_ref() is used to create an initial reference count for the TTM, which will call your initialization function. The GEM design approach has resulted in a memory manager that doesn't provide full coverage of all (or even all common) use cases in its userspace or kernel API. GEM exposes a set of standard memory-related operations to userspace and a set of helper functions to drivers, and let drivers implement hardware-specific operations with their own private API. The GEM userspace API is described in the GEM - the Graphics Execution Manager article on LWN. While slightly outdated, the document provides a good overview of the GEM API principles. Buffer allocation and read and write operations, described as part of the common GEM API, are currently implemented using driver-specific ioctls. GEM is data-agnostic. It manages abstract buffer objects without knowing what individual buffers contain. APIs that require knowledge of buffer contents or purpose, such as buffer allocation or synchronization primitives, are thus outside of the scope of GEM and must be implemented using driver-specific ioctls. On a fundamental level, GEM involves several operations: Memory allocation and freeing Command execution Aperture management at command execution time Buffer object allocation is relatively straightforward and largely provided by Linux's shmem layer, which provides memory to back each object. Device-specific operations, such as command execution, pinning, buffer read & write, mapping, and domain ownership transfers are left to driver-specific ioctls. Drivers that use GEM must set the DRIVER_GEM bit in the struct drm_driver driver_features field. The DRM core will then automatically initialize the GEM core before calling the load operation. Behind the scene, this will create a DRM Memory Manager object which provides an address space pool for object allocation. In a KMS configuration, drivers need to allocate and initialize a command ring buffer following core GEM initialization if required by the hardware. UMA devices usually have what is called a "stolen" memory region, which provides space for the initial framebuffer and large, contiguous memory regions required by the device. This space is typically not managed by GEM, and must be initialized separately into its own DRM MM object. GEM splits creation of GEM objects and allocation of the memory that backs them in two distinct operations. GEM objects are represented by an instance of struct drm_gem_object. Drivers usually need to extend GEM objects with private information and thus create a driver-specific GEM object structure type that embeds an instance of struct drm_gem_object. To create a GEM object, a driver allocates memory for an instance of its specific GEM object type and initializes the embedded struct drm_gem_object with a call to drm_gem_object_init. The function takes a pointer to the DRM device, a pointer to the GEM object and the buffer object size in bytes. GEM uses shmem to allocate anonymous pageable memory. drm_gem_object_init will create an shmfs file of the requested size and store it into the struct drm_gem_object filp field. The memory is used as either main storage for the object when the graphics hardware uses system memory directly or as a backing store otherwise. Drivers are responsible for the actual physical pages allocation by calling shmem_read_mapping_page_gfp for each page. Note that they can decide to allocate pages when initializing the GEM object, or to delay allocation until the memory is needed (for instance when a page fault occurs as a result of a userspace memory access or when the driver needs to start a DMA transfer involving the memory). Anonymous pageable memory allocation is not always desired, for instance when the hardware requires physically contiguous system memory as is often the case in embedded devices. Drivers can create GEM objects with no shmfs backing (called private GEM objects) by initializing them with a call to drm_gem_private_object_init instead of drm_gem_object_init. Storage for private GEM objects must be managed by drivers. Drivers that do not need to extend GEM objects with private information can call the drm_gem_object_alloc function to allocate and initialize a struct drm_gem_object instance. The GEM core will call the optional driver gem_init_object operation after initializing the GEM object with drm_gem_object_init. int (*gem_init_object) (struct drm_gem_object *obj); No alloc-and-init function exists for private GEM objects. All GEM objects are reference-counted by the GEM core. References can be acquired and release by calling drm_gem_object_reference and drm_gem_object_unreference respectively. The caller must hold the drm_device struct_mutex lock. As a convenience, GEM provides the drm_gem_object_reference_unlocked and drm_gem_object_unreference_unlocked functions that can be called without holding the lock. When the last reference to a GEM object is released the GEM core calls the drm_driver gem_free_object operation. That operation is mandatory for GEM-enabled drivers and must free the GEM object and all associated resources. void (*gem_free_object) (struct drm_gem_object *obj); Drivers are responsible for freeing all GEM object resources, including the resources created by the GEM core. If an mmap offset has been created for the object (in which case drm_gem_object::map_list::map is not NULL) it must be freed by a call to drm_gem_free_mmap_offset. The shmfs backing store must be released by calling drm_gem_object_release (that function can safely be called if no shmfs backing store has been created). Communication between userspace and the kernel refers to GEM objects using local handles, global names or, more recently, file descriptors. All of those are 32-bit integer values; the usual Linux kernel limits apply to the file descriptors. GEM handles are local to a DRM file. Applications get a handle to a GEM object through a driver-specific ioctl, and can use that handle to refer to the GEM object in other standard or driver-specific ioctls. Closing a DRM file handle frees all its GEM handles and dereferences the associated GEM objects. To create a handle for a GEM object drivers call drm_gem_handle_create. The function takes a pointer to the DRM file and the GEM object and returns a locally unique handle. When the handle is no longer needed drivers delete it with a call to drm_gem_handle_delete. Finally the GEM object associated with a handle can be retrieved by a call to drm_gem_object_lookup. Handles don't take ownership of GEM objects, they only take a reference to the object that will be dropped when the handle is destroyed. To avoid leaking GEM objects, drivers must make sure they drop the reference(s) they own (such as the initial reference taken at object creation time) as appropriate, without any special consideration for the handle. For example, in the particular case of combined GEM object and handle creation in the implementation of the dumb_create operation, drivers must drop the initial reference to the GEM object before returning the handle. GEM names are similar in purpose to handles but are not local to DRM files. They can be passed between processes to reference a GEM object globally. Names can't be used directly to refer to objects in the DRM API, applications must convert handles to names and names to handles using the DRM_IOCTL_GEM_FLINK and DRM_IOCTL_GEM_OPEN ioctls respectively. The conversion is handled by the DRM core without any driver-specific support. GEM also supports buffer sharing with dma-buf file descriptors through PRIME. GEM-based drivers must use the provided helpers functions to implement the exporting and importing correctly. See . Since sharing file descriptors is inherently more secure than the easily guessable and global GEM names it is the preferred buffer sharing mechanism. Sharing buffers through GEM names is only supported for legacy userspace. Furthermore PRIME also allows cross-device buffer sharing since it is based on dma-bufs. Because mapping operations are fairly heavyweight GEM favours read/write-like access to buffers, implemented through driver-specific ioctls, over mapping buffers to userspace. However, when random access to the buffer is needed (to perform software rendering for instance), direct access to the object can be more efficient. The mmap system call can't be used directly to map GEM objects, as they don't have their own file handle. Two alternative methods currently co-exist to map GEM objects to userspace. The first method uses a driver-specific ioctl to perform the mapping operation, calling do_mmap under the hood. This is often considered dubious, seems to be discouraged for new GEM-enabled drivers, and will thus not be described here. The second method uses the mmap system call on the DRM file handle. void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset); DRM identifies the GEM object to be mapped by a fake offset passed through the mmap offset argument. Prior to being mapped, a GEM object must thus be associated with a fake offset. To do so, drivers must call drm_gem_create_mmap_offset on the object. The function allocates a fake offset range from a pool and stores the offset divided by PAGE_SIZE in obj->map_list.hash.key. Care must be taken not to call drm_gem_create_mmap_offset if a fake offset has already been allocated for the object. This can be tested by obj->map_list.map being non-NULL. Once allocated, the fake offset value (obj->map_list.hash.key << PAGE_SHIFT) must be passed to the application in a driver-specific way and can then be used as the mmap offset argument. The GEM core provides a helper method drm_gem_mmap to handle object mapping. The method can be set directly as the mmap file operation handler. It will look up the GEM object based on the offset value and set the VMA operations to the drm_driver gem_vm_ops field. Note that drm_gem_mmap doesn't map memory to userspace, but relies on the driver-provided fault handler to map pages individually. To use drm_gem_mmap, drivers must fill the struct drm_driver gem_vm_ops field with a pointer to VM operations. struct vm_operations_struct *gem_vm_ops struct vm_operations_struct { void (*open)(struct vm_area_struct * area); void (*close)(struct vm_area_struct * area); int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf); }; The open and close operations must update the GEM object reference count. Drivers can use the drm_gem_vm_open and drm_gem_vm_close helper functions directly as open and close handlers. The fault operation handler is responsible for mapping individual pages to userspace when a page fault occurs. Depending on the memory allocation scheme, drivers can allocate pages at fault time, or can decide to allocate memory for the GEM object at the time the object is created. Drivers that want to map the GEM object upfront instead of handling page faults can implement their own mmap file operation handler. When mapped to the device or used in a command buffer, backing pages for an object are flushed to memory and marked write combined so as to be coherent with the GPU. Likewise, if the CPU accesses an object after the GPU has finished rendering to the object, then the object must be made coherent with the CPU's view of memory, usually involving GPU cache flushing of various kinds. This core CPU<->GPU coherency management is provided by a device-specific ioctl, which evaluates an object's current domain and performs any necessary flushing or synchronization to put the object into the desired coherency domain (note that the object may be busy, i.e. an active render target; in that case, setting the domain blocks the client and waits for rendering to complete before performing any necessary flushing operations). Perhaps the most important GEM function for GPU devices is providing a command execution interface to clients. Client programs construct command buffers containing references to previously allocated memory objects, and then submit them to GEM. At that point, GEM takes care to bind all the objects into the GTT, execute the buffer, and provide necessary synchronization between clients accessing the same buffers. This often involves evicting some objects from the GTT and re-binding others (a fairly expensive operation), and providing relocation support which hides fixed GTT offsets from clients. Clients must take care not to submit command buffers that reference more objects than can fit in the GTT; otherwise, GEM will reject them and no rendering will occur. Similarly, if several objects in the buffer require fence registers to be allocated for correct rendering (e.g. 2D blits on pre-965 chips), care must be taken not to require more fence registers than are available to the client. Such resource management should be abstracted from the client in libdrm. Kernel Hackers Manual July 2017 drm_gem_object_init 9 4.1.27 drm_gem_object_init initialize an allocated shmem-backed GEM object int drm_gem_object_init struct drm_device * dev struct drm_gem_object * obj size_t size dev drm_device the object should be initialized for obj drm_gem_object to initialize size object size Initialize an already allocated GEM object of the specified size with shmfs backing store. Kernel Hackers Manual July 2017 drm_gem_private_object_init 9 4.1.27 drm_gem_private_object_init initialize an allocated private GEM object void drm_gem_private_object_init struct drm_device * dev struct drm_gem_object * obj size_t size dev drm_device the object should be initialized for obj drm_gem_object to initialize size object size Initialize an already allocated GEM object of the specified size with no GEM provided backing store. Instead the caller is responsible for backing the object and handling it. Kernel Hackers Manual July 2017 drm_gem_handle_delete 9 4.1.27 drm_gem_handle_delete deletes the given file-private handle int drm_gem_handle_delete struct drm_file * filp u32 handle filp drm file-private structure to use for the handle look up handle userspace handle to delete Removes the GEM handle from the filp lookup table and if this is the last handle also cleans up linked resources like GEM names. Kernel Hackers Manual July 2017 drm_gem_dumb_destroy 9 4.1.27 drm_gem_dumb_destroy dumb fb callback helper for gem based drivers int drm_gem_dumb_destroy struct drm_file * file struct drm_device * dev uint32_t handle file drm file-private structure to remove the dumb handle from dev corresponding drm_device handle the dumb handle to remove This implements the ->dumb_destroy kms driver callback for drivers which use gem to manage their backing storage. Kernel Hackers Manual July 2017 drm_gem_handle_create 9 4.1.27 drm_gem_handle_create create a gem handle for an object int drm_gem_handle_create struct drm_file * file_priv struct drm_gem_object * obj u32 * handlep file_priv drm file-private structure to register the handle for obj object to register handlep pionter to return the created handle to the caller Create a handle for this object. This adds a handle reference to the object, which includes a regular reference count. Callers will likely want to dereference the object afterwards. Kernel Hackers Manual July 2017 drm_gem_free_mmap_offset 9 4.1.27 drm_gem_free_mmap_offset release a fake mmap offset for an object void drm_gem_free_mmap_offset struct drm_gem_object * obj obj obj in question This routine frees fake offsets allocated by drm_gem_create_mmap_offset. Kernel Hackers Manual July 2017 drm_gem_create_mmap_offset_size 9 4.1.27 drm_gem_create_mmap_offset_size create a fake mmap offset for an object int drm_gem_create_mmap_offset_size struct drm_gem_object * obj size_t size obj obj in question size the virtual size GEM memory mapping works by handing back to userspace a fake mmap offset it can use in a subsequent mmap(2) call. The DRM core code then looks up the object based on the offset and sets up the various memory mapping structures. This routine allocates and attaches a fake offset for obj, in cases where the virtual size differs from the physical size (ie. obj->size). Otherwise just use drm_gem_create_mmap_offset. Kernel Hackers Manual July 2017 drm_gem_create_mmap_offset 9 4.1.27 drm_gem_create_mmap_offset create a fake mmap offset for an object int drm_gem_create_mmap_offset struct drm_gem_object * obj obj obj in question GEM memory mapping works by handing back to userspace a fake mmap offset it can use in a subsequent mmap(2) call. The DRM core code then looks up the object based on the offset and sets up the various memory mapping structures. This routine allocates and attaches a fake offset for obj. Kernel Hackers Manual July 2017 drm_gem_get_pages 9 4.1.27 drm_gem_get_pages helper to allocate backing pages for a GEM object from shmem struct page ** drm_gem_get_pages struct drm_gem_object * obj obj obj in question This reads the page-array of the shmem-backing storage of the given gem object. An array of pages is returned. If a page is not allocated or swapped-out, this will allocate/swap-in the required pages. Note that the whole object is covered by the page-array and pinned in memory. Use drm_gem_put_pages to release the array and unpin all pages. This uses the GFP-mask set on the shmem-mapping (see mapping_set_gfp_mask). If you require other GFP-masks, you have to do those allocations yourself. Note that you are not allowed to change gfp-zones during runtime. That is, shmem_read_mapping_page_gfp must be called with the same gfp_zone(gfp) as set during initialization. If you have special zone constraints, set them after drm_gem_init_object via mapping_set_gfp_mask. shmem-core takes care to keep pages in the required zone during swap-in. Kernel Hackers Manual July 2017 drm_gem_put_pages 9 4.1.27 drm_gem_put_pages helper to free backing pages for a GEM object void drm_gem_put_pages struct drm_gem_object * obj struct page ** pages bool dirty bool accessed obj obj in question pages pages to free dirty if true, pages will be marked as dirty accessed if true, the pages will be marked as accessed Kernel Hackers Manual July 2017 drm_gem_object_free 9 4.1.27 drm_gem_object_free free a GEM object void drm_gem_object_free struct kref * kref kref kref of the object to free Called after the last reference to the object has been lost. Must be called holding struct_ mutex Frees the object Kernel Hackers Manual July 2017 drm_gem_mmap_obj 9 4.1.27 drm_gem_mmap_obj memory map a GEM object int drm_gem_mmap_obj struct drm_gem_object * obj unsigned long obj_size struct vm_area_struct * vma obj the GEM object to map obj_size the object size to be mapped, in bytes vma VMA for the area to be mapped Set up the VMA to prepare mapping of the GEM object using the gem_vm_ops provided by the driver. Depending on their requirements, drivers can either provide a fault handler in their gem_vm_ops (in which case any accesses to the object will be trapped, to perform migration, GTT binding, surface register allocation, or performance monitoring), or mmap the buffer memory synchronously after calling drm_gem_mmap_obj. This function is mainly intended to implement the DMABUF mmap operation, when the GEM object is not looked up based on its fake offset. To implement the DRM mmap operation, drivers should use the drm_gem_mmap function. drm_gem_mmap_obj assumes the user is granted access to the buffer while drm_gem_mmap prevents unprivileged users from mapping random objects. So callers must verify access restrictions before calling this helper. This function has to be protected with dev->struct_mutex Return 0 or success or -EINVAL if the object size is smaller than the VMA size, or if no gem_vm_ops are provided. Kernel Hackers Manual July 2017 drm_gem_mmap 9 4.1.27 drm_gem_mmap memory map routine for GEM objects int drm_gem_mmap struct file * filp struct vm_area_struct * vma filp DRM file pointer vma VMA for the area to be mapped If a driver supports GEM object mapping, mmap calls on the DRM file descriptor will end up here. Look up the GEM object based on the offset passed in (vma->vm_pgoff will contain the fake offset we created when the GTT map ioctl was called on the object) and map it with a call to drm_gem_mmap_obj. If the caller is not granted access to the buffer object, the mmap will fail with EACCES. Please see the vma manager for more information. The vma-manager is responsible to map arbitrary driver-dependent memory regions into the linear user address-space. It provides offsets to the caller which can then be used on the address_space of the drm-device. It takes care to not overlap regions, size them appropriately and to not confuse mm-core by inconsistent fake vm_pgoff fields. Drivers shouldn't use this for object placement in VMEM. This manager should only be used to manage mappings into linear user-space VMs. We use drm_mm as backend to manage object allocations. But it is highly optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to speed up offset lookups. You must not use multiple offset managers on a single address_space. Otherwise, mm-core will be unable to tear down memory mappings as the VM will no longer be linear. This offset manager works on page-based addresses. That is, every argument and return code (with the exception of drm_vma_node_offset_addr) is given in number of pages, not number of bytes. That means, object sizes and offsets must always be page-aligned (as usual). If you want to get a valid byte-based user-space address for a given offset, please see drm_vma_node_offset_addr. Additionally to offset management, the vma offset manager also handles access management. For every open-file context that is allowed to access a given node, you must call drm_vma_node_allow. Otherwise, an mmap call on this open-file with the offset of the node will fail with -EACCES. To revoke access again, use drm_vma_node_revoke. However, the caller is responsible for destroying already existing mappings, if required. Kernel Hackers Manual July 2017 drm_vma_offset_manager_init 9 4.1.27 drm_vma_offset_manager_init Initialize new offset-manager void drm_vma_offset_manager_init struct drm_vma_offset_manager * mgr unsigned long page_offset unsigned long size mgr Manager object page_offset Offset of available memory area (page-based) size Size of available address space range (page-based) Initialize a new offset-manager. The offset and area size available for the manager are given as page_offset and size. Both are interpreted as page-numbers, not bytes. Adding/removing nodes from the manager is locked internally and protected against concurrent access. However, node allocation and destruction is left for the caller. While calling into the vma-manager, a given node must always be guaranteed to be referenced. Kernel Hackers Manual July 2017 drm_vma_offset_manager_destroy 9 4.1.27 drm_vma_offset_manager_destroy Destroy offset manager void drm_vma_offset_manager_destroy struct drm_vma_offset_manager * mgr mgr Manager object Destroy an object manager which was previously created via drm_vma_offset_manager_init. The caller must remove all allocated nodes before destroying the manager. Otherwise, drm_mm will refuse to free the requested resources. The manager must not be accessed after this function is called. Kernel Hackers Manual July 2017 drm_vma_offset_lookup 9 4.1.27 drm_vma_offset_lookup Find node in offset space struct drm_vma_offset_node * drm_vma_offset_lookup struct drm_vma_offset_manager * mgr unsigned long start unsigned long pages mgr Manager object start Start address for object (page-based) pages Size of object (page-based) Find a node given a start address and object size. This returns the _best_ match for the given node. That is, start may point somewhere into a valid region and the given node will be returned, as long as the node spans the whole requested area (given the size in number of pages as pages). Returns NULL if no suitable node can be found. Otherwise, the best match is returned. It's the caller's responsibility to make sure the node doesn't get destroyed before the caller can access it. Kernel Hackers Manual July 2017 drm_vma_offset_lookup_locked 9 4.1.27 drm_vma_offset_lookup_locked Find node in offset space struct drm_vma_offset_node * drm_vma_offset_lookup_locked struct drm_vma_offset_manager * mgr unsigned long start unsigned long pages mgr Manager object start Start address for object (page-based) pages Size of object (page-based) Same as drm_vma_offset_lookup but requires the caller to lock offset lookup manually. See drm_vma_offset_lock_lookup for an example. Returns NULL if no suitable node can be found. Otherwise, the best match is returned. Kernel Hackers Manual July 2017 drm_vma_offset_add 9 4.1.27 drm_vma_offset_add Add offset node to manager int drm_vma_offset_add struct drm_vma_offset_manager * mgr struct drm_vma_offset_node * node unsigned long pages mgr Manager object node Node to be added pages Allocation size visible to user-space (in number of pages) Add a node to the offset-manager. If the node was already added, this does nothing and return 0. pages is the size of the object given in number of pages. After this call succeeds, you can access the offset of the node until it is removed again. If this call fails, it is safe to retry the operation or call drm_vma_offset_remove, anyway. However, no cleanup is required in that case. pages is not required to be the same size as the underlying memory object that you want to map. It only limits the size that user-space can map into their address space. 0 on success, negative error code on failure. Kernel Hackers Manual July 2017 drm_vma_offset_remove 9 4.1.27 drm_vma_offset_remove Remove offset node from manager void drm_vma_offset_remove struct drm_vma_offset_manager * mgr struct drm_vma_offset_node * node mgr Manager object node Node to be removed Remove a node from the offset manager. If the node wasn't added before, this does nothing. After this call returns, the offset and size will be 0 until a new offset is allocated via drm_vma_offset_add again. Helper functions like drm_vma_node_start and drm_vma_node_offset_addr will return 0 if no offset is allocated. Kernel Hackers Manual July 2017 drm_vma_node_allow 9 4.1.27 drm_vma_node_allow Add open-file to list of allowed users int drm_vma_node_allow struct drm_vma_offset_node * node struct file * filp node Node to modify filp Open file to add Add filp to the list of allowed open-files for this node. If filp is already on this list, the ref-count is incremented. The list of allowed-users is preserved across drm_vma_offset_add and drm_vma_offset_remove calls. You may even call it if the node is currently not added to any offset-manager. You must remove all open-files the same number of times as you added them before destroying the node. Otherwise, you will leak memory. This is locked against concurrent access internally. 0 on success, negative error code on internal failure (out-of-mem) Kernel Hackers Manual July 2017 drm_vma_node_revoke 9 4.1.27 drm_vma_node_revoke Remove open-file from list of allowed users void drm_vma_node_revoke struct drm_vma_offset_node * node struct file * filp node Node to modify filp Open file to remove Decrement the ref-count of filp in the list of allowed open-files on node. If the ref-count drops to zero, remove filp from the list. You must call this once for every drm_vma_node_allow on filp. This is locked against concurrent access internally. If filp is not on the list, nothing is done. Kernel Hackers Manual July 2017 drm_vma_node_is_allowed 9 4.1.27 drm_vma_node_is_allowed Check whether an open-file is granted access bool drm_vma_node_is_allowed struct drm_vma_offset_node * node struct file * filp node Node to check filp Open-file to check for Search the list in node whether filp is currently on the list of allowed open-files (see drm_vma_node_allow). This is locked against concurrent access internally. true iff filp is on the list Kernel Hackers Manual July 2017 drm_vma_offset_exact_lookup 9 4.1.27 drm_vma_offset_exact_lookup Look up node by exact address struct drm_vma_offset_node * drm_vma_offset_exact_lookup struct drm_vma_offset_manager * mgr unsigned long start unsigned long pages mgr Manager object start Start address (page-based, not byte-based) pages Size of object (page-based) Same as drm_vma_offset_lookup but does not allow any offset into the node. It only returns the exact object with the given start address. Node at exact start address start. Kernel Hackers Manual July 2017 drm_vma_offset_lock_lookup 9 4.1.27 drm_vma_offset_lock_lookup Lock lookup for extended private use void drm_vma_offset_lock_lookup struct drm_vma_offset_manager * mgr mgr Manager object Lock VMA manager for extended lookups. Only *_locked VMA function calls are allowed while holding this lock. All other contexts are blocked from VMA until the lock is released via drm_vma_offset_unlock_lookup. Use this if you need to take a reference to the objects returned by drm_vma_offset_lookup_locked before releasing this lock again. This lock must not be used for anything else than extended lookups. You must not call any other VMA helpers while holding this lock. You're in atomic-context while holding this lock! drm_vma_offset_lock_lookup(mgr); node = drm_vma_offset_lookup_locked(mgr); if (node) kref_get_unless_zero(container_of(node, sth, entr)); drm_vma_offset_unlock_lookup(mgr); Kernel Hackers Manual July 2017 drm_vma_offset_unlock_lookup 9 4.1.27 drm_vma_offset_unlock_lookup Unlock lookup for extended private use void drm_vma_offset_unlock_lookup struct drm_vma_offset_manager * mgr mgr Manager object Release lookup-lock. See drm_vma_offset_lock_lookup for more information. Kernel Hackers Manual July 2017 drm_vma_node_reset 9 4.1.27 drm_vma_node_reset Initialize or reset node object void drm_vma_node_reset struct drm_vma_offset_node * node node Node to initialize or reset Reset a node to its initial state. This must be called before using it with any VMA offset manager. This must not be called on an already allocated node, or you will leak memory. Kernel Hackers Manual July 2017 drm_vma_node_start 9 4.1.27 drm_vma_node_start Return start address for page-based addressing unsigned long drm_vma_node_start struct drm_vma_offset_node * node node Node to inspect Return the start address of the given node. This can be used as offset into the linear VM space that is provided by the VMA offset manager. Note that this can only be used for page-based addressing. If you need a proper offset for user-space mappings, you must apply << PAGE_SHIFT or use the drm_vma_node_offset_addr helper instead. Start address of node for page-based addressing. 0 if the node does not have an offset allocated. Kernel Hackers Manual July 2017 drm_vma_node_size 9 4.1.27 drm_vma_node_size Return size (page-based) unsigned long drm_vma_node_size struct drm_vma_offset_node * node node Node to inspect Return the size as number of pages for the given node. This is the same size that was passed to drm_vma_offset_add. If no offset is allocated for the node, this is 0. Size of node as number of pages. 0 if the node does not have an offset allocated. Kernel Hackers Manual July 2017 drm_vma_node_has_offset 9 4.1.27 drm_vma_node_has_offset Check whether node is added to offset manager bool drm_vma_node_has_offset struct drm_vma_offset_node * node node Node to be checked true iff the node was previously allocated an offset and added to an vma offset manager. Kernel Hackers Manual July 2017 drm_vma_node_offset_addr 9 4.1.27 drm_vma_node_offset_addr Return sanitized offset for user-space mmaps __u64 drm_vma_node_offset_addr struct drm_vma_offset_node * node node Linked offset node Same as drm_vma_node_start but returns the address as a valid offset that can be used for user-space mappings during mmap. This must not be called on unlinked nodes. Offset of node for byte-based addressing. 0 if the node does not have an object allocated. Kernel Hackers Manual July 2017 drm_vma_node_unmap 9 4.1.27 drm_vma_node_unmap Unmap offset node void drm_vma_node_unmap struct drm_vma_offset_node * node struct address_space * file_mapping node Offset node file_mapping Address space to unmap node from Unmap all userspace mappings for a given offset node. The mappings must be associated with the file_mapping address-space. If no offset exists nothing is done. This call is unlocked. The caller must guarantee that drm_vma_offset_remove is not called on this node concurrently. Kernel Hackers Manual July 2017 drm_vma_node_verify_access 9 4.1.27 drm_vma_node_verify_access Access verification helper for TTM int drm_vma_node_verify_access struct drm_vma_offset_node * node struct file * filp node Offset node filp Open-file This checks whether filp is granted access to node. It is the same as drm_vma_node_is_allowed but suitable as drop-in helper for TTM verify_access callbacks. 0 if access is granted, -EACCES otherwise. PRIME is the cross device buffer sharing framework in drm, originally created for the OPTIMUS range of multi-gpu platforms. To userspace PRIME buffers are dma-buf based file descriptors. Similar to GEM global names, PRIME file descriptors are also used to share buffer objects across processes. They offer additional security: as file descriptors must be explicitly sent over UNIX domain sockets to be shared between applications, they can't be guessed like the globally unique GEM names. Drivers that support the PRIME API must set the DRIVER_PRIME bit in the struct drm_driver driver_features field, and implement the prime_handle_to_fd and prime_fd_to_handle operations. int (*prime_handle_to_fd)(struct drm_device *dev, struct drm_file *file_priv, uint32_t handle, uint32_t flags, int *prime_fd); int (*prime_fd_to_handle)(struct drm_device *dev, struct drm_file *file_priv, int prime_fd, uint32_t *handle); Those two operations convert a handle to a PRIME file descriptor and vice versa. Drivers must use the kernel dma-buf buffer sharing framework to manage the PRIME file descriptors. Similar to the mode setting API PRIME is agnostic to the underlying buffer object manager, as long as handles are 32bit unsigned integers. While non-GEM drivers must implement the operations themselves, GEM drivers must use the drm_gem_prime_handle_to_fd and drm_gem_prime_fd_to_handle helper functions. Those helpers rely on the driver gem_prime_export and gem_prime_import operations to create a dma-buf instance from a GEM object (dma-buf exporter role) and to create a GEM object from a dma-buf instance (dma-buf importer role). struct dma_buf * (*gem_prime_export)(struct drm_device *dev, struct drm_gem_object *obj, int flags); struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev, struct dma_buf *dma_buf); These two operations are mandatory for GEM drivers that support PRIME. Drivers can implement gem_prime_export and gem_prime_import in terms of simpler APIs by using the helper functions drm_gem_prime_export and drm_gem_prime_import. These functions implement dma-buf support in terms of five lower-level driver callbacks: Export callbacks: - gem_prime_pin (optional): prepare a GEM object for exporting - gem_prime_get_sg_table: provide a scatter/gather table of pinned pages - gem_prime_vmap: vmap a buffer exported by your driver - gem_prime_vunmap: vunmap a buffer exported by your driver Import callback: - gem_prime_import_sg_table (import): produce a GEM object from another driver's scatter/gather table Kernel Hackers Manual July 2017 drm_gem_dmabuf_release 9 4.1.27 drm_gem_dmabuf_release dma_buf release implementation for GEM void drm_gem_dmabuf_release struct dma_buf * dma_buf dma_buf buffer to be released Generic release function for dma_bufs exported as PRIME buffers. GEM drivers must use this in their dma_buf ops structure as the release callback. Kernel Hackers Manual July 2017 drm_gem_prime_export 9 4.1.27 drm_gem_prime_export helper library implementation of the export callback struct dma_buf * drm_gem_prime_export struct drm_device * dev struct drm_gem_object * obj int flags dev drm_device to export from obj GEM object to export flags flags like DRM_CLOEXEC This is the implementation of the gem_prime_export functions for GEM drivers using the PRIME helpers. Kernel Hackers Manual July 2017 drm_gem_prime_handle_to_fd 9 4.1.27 drm_gem_prime_handle_to_fd PRIME export function for GEM drivers int drm_gem_prime_handle_to_fd struct drm_device * dev struct drm_file * file_priv uint32_t handle uint32_t flags int * prime_fd dev dev to export the buffer from file_priv drm file-private structure handle buffer handle to export flags flags like DRM_CLOEXEC prime_fd pointer to storage for the fd id of the create dma-buf This is the PRIME export function which must be used mandatorily by GEM drivers to ensure correct lifetime management of the underlying GEM object. The actual exporting from GEM object to a dma-buf is done through the gem_prime_export driver callback. Kernel Hackers Manual July 2017 drm_gem_prime_import 9 4.1.27 drm_gem_prime_import helper library implementation of the import callback struct drm_gem_object * drm_gem_prime_import struct drm_device * dev struct dma_buf * dma_buf dev drm_device to import into dma_buf dma-buf object to import This is the implementation of the gem_prime_import functions for GEM drivers using the PRIME helpers. Kernel Hackers Manual July 2017 drm_gem_prime_fd_to_handle 9 4.1.27 drm_gem_prime_fd_to_handle PRIME import function for GEM drivers int drm_gem_prime_fd_to_handle struct drm_device * dev struct drm_file * file_priv int prime_fd uint32_t * handle dev dev to export the buffer from file_priv drm file-private structure prime_fd fd id of the dma-buf which should be imported handle pointer to storage for the handle of the imported buffer object This is the PRIME import function which must be used mandatorily by GEM drivers to ensure correct lifetime management of the underlying GEM object. The actual importing of GEM object from the dma-buf is done through the gem_import_export driver callback. Kernel Hackers Manual July 2017 drm_prime_pages_to_sg 9 4.1.27 drm_prime_pages_to_sg converts a page array into an sg list struct sg_table * drm_prime_pages_to_sg struct page ** pages unsigned int nr_pages pages pointer to the array of page pointers to convert nr_pages length of the page vector This helper creates an sg table object from a set of pages the driver is responsible for mapping the pages into the importers address space for use with dma_buf itself. Kernel Hackers Manual July 2017 drm_prime_sg_to_page_addr_arrays 9 4.1.27 drm_prime_sg_to_page_addr_arrays convert an sg table into a page array int drm_prime_sg_to_page_addr_arrays struct sg_table * sgt struct page ** pages dma_addr_t * addrs int max_pages sgt scatter-gather table to convert pages array of page pointers to store the page array in addrs optional array to store the dma bus address of each page max_pages size of both the passed-in arrays Exports an sg table into an array of pages and addresses. This is currently required by the TTM driver in order to do correct fault handling. Kernel Hackers Manual July 2017 drm_prime_gem_destroy 9 4.1.27 drm_prime_gem_destroy helper to clean up a PRIME-imported GEM object void drm_prime_gem_destroy struct drm_gem_object * obj struct sg_table * sg obj GEM object which was created from a dma-buf sg the sg-table which was pinned at import time This is the cleanup functions which GEM drivers need to call when they use drm_gem_prime_import to import dma-bufs. drm_mm provides a simple range allocator. The drivers are free to use the resource allocator from the linux core if it suits them, the upside of drm_mm is that it's in the DRM core. Which means that it's easier to extend for some of the crazier special purpose needs of gpus. The main data struct is drm_mm, allocations are tracked in drm_mm_node. Drivers are free to embed either of them into their own suitable datastructures. drm_mm itself will not do any allocations of its own, so if drivers choose not to embed nodes they need to still allocate them themselves. The range allocator also supports reservation of preallocated blocks. This is useful for taking over initial mode setting configurations from the firmware, where an object needs to be created which exactly matches the firmware's scanout target. As long as the range is still free it can be inserted anytime after the allocator is initialized, which helps with avoiding looped depencies in the driver load sequence. drm_mm maintains a stack of most recently freed holes, which of all simplistic datastructures seems to be a fairly decent approach to clustering allocations and avoiding too much fragmentation. This means free space searches are O(num_holes). Given that all the fancy features drm_mm supports something better would be fairly complex and since gfx thrashing is a fairly steep cliff not a real concern. Removing a node again is O(1). drm_mm supports a few features: Alignment and range restrictions can be supplied. Further more every drm_mm_node has a color value (which is just an opaqua unsigned long) which in conjunction with a driver callback can be used to implement sophisticated placement restrictions. The i915 DRM driver uses this to implement guard pages between incompatible caching domains in the graphics TT. Two behaviors are supported for searching and allocating: bottom-up and top-down. The default is bottom-up. Top-down allocation can be used if the memory area has different restrictions, or just to reduce fragmentation. Finally iteration helpers to walk all nodes and all holes are provided as are some basic allocator dumpers for debugging. Very often GPUs need to have continuous allocations for a given object. When evicting objects to make space for a new one it is therefore not most efficient when we simply start to select all objects from the tail of an LRU until there's a suitable hole: Especially for big objects or nodes that otherwise have special allocation constraints there's a good chance we evict lots of (smaller) objects unecessarily. The DRM range allocator supports this use-case through the scanning interfaces. First a scan operation needs to be initialized with drm_mm_init_scan or drm_mm_init_scan_with_range. The the driver adds objects to the roaster (probably by walking an LRU list, but this can be freely implemented) until a suitable hole is found or there's no further evitable object. The the driver must walk through all objects again in exactly the reverse order to restore the allocator state. Note that while the allocator is used in the scan mode no other operation is allowed. Finally the driver evicts all objects selected in the scan. Adding and removing an object is O(1), and since freeing a node is also O(1) the overall complexity is O(scanned_objects). So like the free stack which needs to be walked before a scan operation even begins this is linear in the number of objects. It doesn't seem to hurt badly. Kernel Hackers Manual July 2017 drm_mm_reserve_node 9 4.1.27 drm_mm_reserve_node insert an pre-initialized node int drm_mm_reserve_node struct drm_mm * mm struct drm_mm_node * node mm drm_mm allocator to insert node into node drm_mm_node to insert This functions inserts an already set-up drm_mm_node into the allocator, meaning that start, size and color must be set by the caller. This is useful to initialize the allocator with preallocated objects which must be set-up before the range allocator can be set-up, e.g. when taking over a firmware framebuffer. 0 on success, -ENOSPC if there's no hole where node is. Kernel Hackers Manual July 2017 drm_mm_insert_node_generic 9 4.1.27 drm_mm_insert_node_generic search for space and insert node int drm_mm_insert_node_generic struct drm_mm * mm struct drm_mm_node * node u64 size unsigned alignment unsigned long color enum drm_mm_search_flags sflags enum drm_mm_allocator_flags aflags mm drm_mm to allocate from node preallocate node to insert size size of the allocation alignment alignment of the allocation color opaque tag value to use for this node sflags flags to fine-tune the allocation search aflags flags to fine-tune the allocation behavior The preallocated node must be cleared to 0. 0 on success, -ENOSPC if there's no suitable hole. Kernel Hackers Manual July 2017 drm_mm_insert_node_in_range_generic 9 4.1.27 drm_mm_insert_node_in_range_generic ranged search for space and insert node int drm_mm_insert_node_in_range_generic struct drm_mm * mm struct drm_mm_node * node u64 size unsigned alignment unsigned long color u64 start u64 end enum drm_mm_search_flags sflags enum drm_mm_allocator_flags aflags mm drm_mm to allocate from node preallocate node to insert size size of the allocation alignment alignment of the allocation color opaque tag value to use for this node start start of the allowed range for this node end end of the allowed range for this node sflags flags to fine-tune the allocation search aflags flags to fine-tune the allocation behavior The preallocated node must be cleared to 0. 0 on success, -ENOSPC if there's no suitable hole. Kernel Hackers Manual July 2017 drm_mm_remove_node 9 4.1.27 drm_mm_remove_node Remove a memory node from the allocator. void drm_mm_remove_node struct drm_mm_node * node node drm_mm_node to remove This just removes a node from its drm_mm allocator. The node does not need to be cleared again before it can be re-inserted into this or any other drm_mm allocator. It is a bug to call this function on a un-allocated node. Kernel Hackers Manual July 2017 drm_mm_replace_node 9 4.1.27 drm_mm_replace_node move an allocation from old to new void drm_mm_replace_node struct drm_mm_node * old struct drm_mm_node * new old drm_mm_node to remove from the allocator new drm_mm_node which should inherit old's allocation This is useful for when drivers embed the drm_mm_node structure and hence can't move allocations by reassigning pointers. It's a combination of remove and insert with the guarantee that the allocation start will match. Kernel Hackers Manual July 2017 drm_mm_init_scan 9 4.1.27 drm_mm_init_scan initialize lru scanning void drm_mm_init_scan struct drm_mm * mm u64 size unsigned alignment unsigned long color mm drm_mm to scan size size of the allocation alignment alignment of the allocation color opaque tag value to use for the allocation This simply sets up the scanning routines with the parameters for the desired hole. Note that there's no need to specify allocation flags, since they only change the place a node is allocated from within a suitable hole. As long as the scan list is non-empty, no other operations than adding/removing nodes to/from the scan list are allowed. Kernel Hackers Manual July 2017 drm_mm_init_scan_with_range 9 4.1.27 drm_mm_init_scan_with_range initialize range-restricted lru scanning void drm_mm_init_scan_with_range struct drm_mm * mm u64 size unsigned alignment unsigned long color u64 start u64 end mm drm_mm to scan size size of the allocation alignment alignment of the allocation color opaque tag value to use for the allocation start start of the allowed range for the allocation end end of the allowed range for the allocation This simply sets up the scanning routines with the parameters for the desired hole. Note that there's no need to specify allocation flags, since they only change the place a node is allocated from within a suitable hole. As long as the scan list is non-empty, no other operations than adding/removing nodes to/from the scan list are allowed. Kernel Hackers Manual July 2017 drm_mm_scan_add_block 9 4.1.27 drm_mm_scan_add_block add a node to the scan list bool drm_mm_scan_add_block struct drm_mm_node * node node drm_mm_node to add Add a node to the scan list that might be freed to make space for the desired hole. True if a hole has been found, false otherwise. Kernel Hackers Manual July 2017 drm_mm_scan_remove_block 9 4.1.27 drm_mm_scan_remove_block remove a node from the scan list bool drm_mm_scan_remove_block struct drm_mm_node * node node drm_mm_node to remove Nodes _must_ be removed in the exact same order from the scan list as they have been added, otherwise the internal state of the memory manager will be corrupted. When the scan list is empty, the selected memory nodes can be freed. An immediately following drm_mm_search_free with !DRM_MM_SEARCH_BEST will then return the just freed block (because its at the top of the free_stack list). True if this block should be evicted, false otherwise. Will always return false when no hole has been found. Kernel Hackers Manual July 2017 drm_mm_clean 9 4.1.27 drm_mm_clean checks whether an allocator is clean bool drm_mm_clean struct drm_mm * mm mm drm_mm allocator to check True if the allocator is completely free, false if there's still a node allocated in it. Kernel Hackers Manual July 2017 drm_mm_init 9 4.1.27 drm_mm_init initialize a drm-mm allocator void drm_mm_init struct drm_mm * mm u64 start u64 size mm the drm_mm structure to initialize start start of the range managed by mm size end of the range managed by mm Note that mm must be cleared to 0 before calling this function. Kernel Hackers Manual July 2017 drm_mm_takedown 9 4.1.27 drm_mm_takedown clean up a drm_mm allocator void drm_mm_takedown struct drm_mm * mm mm drm_mm allocator to clean up Note that it is a bug to call this function on an allocator which is not clean. Kernel Hackers Manual July 2017 drm_mm_debug_table 9 4.1.27 drm_mm_debug_table dump allocator state to dmesg void drm_mm_debug_table struct drm_mm * mm const char * prefix mm drm_mm allocator to dump prefix prefix to use for dumping to dmesg Kernel Hackers Manual July 2017 drm_mm_dump_table 9 4.1.27 drm_mm_dump_table dump allocator state to a seq_file int drm_mm_dump_table struct seq_file * m struct drm_mm * mm m seq_file to dump to mm drm_mm allocator to dump Kernel Hackers Manual July 2017 drm_mm_node_allocated 9 4.1.27 drm_mm_node_allocated checks whether a node is allocated bool drm_mm_node_allocated struct drm_mm_node * node node drm_mm_node to check Drivers should use this helpers for proper encapusulation of drm_mm internals. True if the node is allocated. Kernel Hackers Manual July 2017 drm_mm_initialized 9 4.1.27 drm_mm_initialized checks whether an allocator is initialized bool drm_mm_initialized struct drm_mm * mm mm drm_mm to check Drivers should use this helpers for proper encapusulation of drm_mm internals. True if the mm is initialized. Kernel Hackers Manual July 2017 drm_mm_hole_node_start 9 4.1.27 drm_mm_hole_node_start computes the start of the hole following node u64 drm_mm_hole_node_start struct drm_mm_node * hole_node hole_node drm_mm_node which implicitly tracks the following hole This is useful for driver-sepific debug dumpers. Otherwise drivers should not inspect holes themselves. Drivers must check first whether a hole indeed follows by looking at node->hole_follows. Start of the subsequent hole. Kernel Hackers Manual July 2017 drm_mm_hole_node_end 9 4.1.27 drm_mm_hole_node_end computes the end of the hole following node u64 drm_mm_hole_node_end struct drm_mm_node * hole_node hole_node drm_mm_node which implicitly tracks the following hole This is useful for driver-sepific debug dumpers. Otherwise drivers should not inspect holes themselves. Drivers must check first whether a hole indeed follows by looking at node->hole_follows. End of the subsequent hole. Kernel Hackers Manual July 2017 drm_mm_for_each_node 9 4.1.27 drm_mm_for_each_node iterator to walk over all allocated nodes drm_mm_for_each_node entry mm entry drm_mm_node structure to assign to in each iteration step mm drm_mm allocator to walk This iterator walks over all nodes in the range allocator. It is implemented with list_for_each, so not save against removal of elements. Kernel Hackers Manual July 2017 drm_mm_for_each_hole 9 4.1.27 drm_mm_for_each_hole iterator to walk over all holes drm_mm_for_each_hole entry mm hole_start hole_end entry drm_mm_node used internally to track progress mm drm_mm allocator to walk hole_start ulong variable to assign the hole start to on each iteration hole_end ulong variable to assign the hole end to on each iteration This iterator walks over all holes in the range allocator. It is implemented with list_for_each, so not save against removal of elements. entry is used internally and will not reflect a real drm_mm_node for the very first hole. Hence users of this iterator may not access it. We need to inline list_for_each_entry in order to be able to set hole_start and hole_end on each iteration while keeping the macro sane. The __drm_mm_for_each_hole version is similar, but with added support for going backwards. Kernel Hackers Manual July 2017 drm_mm_insert_node 9 4.1.27 drm_mm_insert_node search for space and insert node int drm_mm_insert_node struct drm_mm * mm struct drm_mm_node * node u64 size unsigned alignment enum drm_mm_search_flags flags mm drm_mm to allocate from node preallocate node to insert size size of the allocation alignment alignment of the allocation flags flags to fine-tune the allocation This is a simplified version of drm_mm_insert_node_generic with color set to 0. The preallocated node must be cleared to 0. 0 on success, -ENOSPC if there's no suitable hole. Kernel Hackers Manual July 2017 drm_mm_insert_node_in_range 9 4.1.27 drm_mm_insert_node_in_range ranged search for space and insert node int drm_mm_insert_node_in_range struct drm_mm * mm struct drm_mm_node * node u64 size unsigned alignment u64 start u64 end enum drm_mm_search_flags flags mm drm_mm to allocate from node preallocate node to insert size size of the allocation alignment alignment of the allocation start start of the allowed range for this node end end of the allowed range for this node flags flags to fine-tune the allocation This is a simplified version of drm_mm_insert_node_in_range_generic with color set to 0. The preallocated node must be cleared to 0. 0 on success, -ENOSPC if there's no suitable hole. The Contiguous Memory Allocator reserves a pool of memory at early boot that is used to service requests for large blocks of contiguous memory. The DRM GEM/CMA helpers use this allocator as a means to provide buffer objects that are physically contiguous in memory. This is useful for display drivers that are unable to map scattered buffers via an IOMMU. Kernel Hackers Manual July 2017 drm_gem_cma_create 9 4.1.27 drm_gem_cma_create allocate an object with the given size struct drm_gem_cma_object * drm_gem_cma_create struct drm_device * drm size_t size drm DRM device size size of the object to allocate This function creates a CMA GEM object and allocates a contiguous chunk of memory as backing store. The backing memory has the writecombine attribute set. A struct drm_gem_cma_object * on success or an ERR_PTR-encoded negative error code on failure. Kernel Hackers Manual July 2017 drm_gem_cma_free_object 9 4.1.27 drm_gem_cma_free_object free resources associated with a CMA GEM object void drm_gem_cma_free_object struct drm_gem_object * gem_obj gem_obj GEM object to free This function frees the backing memory of the CMA GEM object, cleans up the GEM object state and frees the memory used to store the object itself. Drivers using the CMA helpers should set this as their DRM driver's ->gem_free_object callback. Kernel Hackers Manual July 2017 drm_gem_cma_dumb_create_internal 9 4.1.27 drm_gem_cma_dumb_create_internal create a dumb buffer object int drm_gem_cma_dumb_create_internal struct drm_file * file_priv struct drm_device * drm struct drm_mode_create_dumb * args file_priv DRM file-private structure to create the dumb buffer for drm DRM device args IOCTL data This aligns the pitch and size arguments to the minimum required. This is an internal helper that can be wrapped by a driver to account for hardware with more specific alignment requirements. It should not be used directly as the ->dumb_create callback in a DRM driver. 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_gem_cma_dumb_create 9 4.1.27 drm_gem_cma_dumb_create create a dumb buffer object int drm_gem_cma_dumb_create struct drm_file * file_priv struct drm_device * drm struct drm_mode_create_dumb * args file_priv DRM file-private structure to create the dumb buffer for drm DRM device args IOCTL data This function computes the pitch of the dumb buffer and rounds it up to an integer number of bytes per pixel. Drivers for hardware that doesn't have any additional restrictions on the pitch can directly use this function as their ->dumb_create callback. For hardware with additional restrictions, drivers can adjust the fields set up by userspace and pass the IOCTL data along to the drm_gem_cma_dumb_create_internal function. 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_gem_cma_dumb_map_offset 9 4.1.27 drm_gem_cma_dumb_map_offset return the fake mmap offset for a CMA GEM object int drm_gem_cma_dumb_map_offset struct drm_file * file_priv struct drm_device * drm u32 handle u64 * offset file_priv DRM file-private structure containing the GEM object drm DRM device handle GEM object handle offset return location for the fake mmap offset This function look up an object by its handle and returns the fake mmap offset associated with it. Drivers using the CMA helpers should set this as their DRM driver's ->dumb_map_offset callback. 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_gem_cma_mmap 9 4.1.27 drm_gem_cma_mmap memory-map a CMA GEM object int drm_gem_cma_mmap struct file * filp struct vm_area_struct * vma filp file object vma VMA for the area to be mapped This function implements an augmented version of the GEM DRM file mmap In addition to the usual GEM VMA setup it immediately faults in the entire object instead of using on-demaind faulting. Drivers which employ the CMA helpers should use this function as their ->mmap handler in the DRM device file's file_operations structure. 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_gem_cma_describe 9 4.1.27 drm_gem_cma_describe describe a CMA GEM object for debugfs void drm_gem_cma_describe struct drm_gem_cma_object * cma_obj struct seq_file * m cma_obj CMA GEM object m debugfs file handle This function can be used to dump a human-readable representation of the CMA GEM object into a synthetic file. Kernel Hackers Manual July 2017 drm_gem_cma_prime_get_sg_table 9 4.1.27 drm_gem_cma_prime_get_sg_table provide a scatter/gather table of pinned pages for a CMA GEM object struct sg_table * drm_gem_cma_prime_get_sg_table struct drm_gem_object * obj obj GEM object This function exports a scatter/gather table suitable for PRIME usage by calling the standard DMA mapping API. Drivers using the CMA helpers should set this as their DRM driver's ->gem_prime_get_sg_table callback. A pointer to the scatter/gather table of pinned pages or NULL on failure. Kernel Hackers Manual July 2017 drm_gem_cma_prime_import_sg_table 9 4.1.27 drm_gem_cma_prime_import_sg_table produce a CMA GEM object from another driver's scatter/gather table of pinned pages struct drm_gem_object * drm_gem_cma_prime_import_sg_table struct drm_device * dev struct dma_buf_attachment * attach struct sg_table * sgt dev device to import into attach DMA-BUF attachment sgt scatter/gather table of pinned pages This function imports a scatter/gather table exported via DMA-BUF by another driver. Imported buffers must be physically contiguous in memory (i.e. the scatter/gather table must contain a single entry). Drivers that use the CMA helpers should set this as their DRM driver's ->gem_prime_import_sg_table callback. A pointer to a newly created GEM object or an ERR_PTR-encoded negative error code on failure. Kernel Hackers Manual July 2017 drm_gem_cma_prime_mmap 9 4.1.27 drm_gem_cma_prime_mmap memory-map an exported CMA GEM object int drm_gem_cma_prime_mmap struct drm_gem_object * obj struct vm_area_struct * vma obj GEM object vma VMA for the area to be mapped This function maps a buffer imported via DRM PRIME into a userspace process's address space. Drivers that use the CMA helpers should set this as their DRM driver's ->gem_prime_mmap callback. 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_gem_cma_prime_vmap 9 4.1.27 drm_gem_cma_prime_vmap map a CMA GEM object into the kernel's virtual address space void * drm_gem_cma_prime_vmap struct drm_gem_object * obj obj GEM object This function maps a buffer exported via DRM PRIME into the kernel's virtual address space. Since the CMA buffers are already mapped into the kernel virtual address space this simply returns the cached virtual address. Drivers using the CMA helpers should set this as their DRM driver's ->gem_prime_vmap callback. The kernel virtual address of the CMA GEM object's backing store. Kernel Hackers Manual July 2017 drm_gem_cma_prime_vunmap 9 4.1.27 drm_gem_cma_prime_vunmap unmap a CMA GEM object from the kernel's virtual address space void drm_gem_cma_prime_vunmap struct drm_gem_object * obj void * vaddr obj GEM object vaddr kernel virtual address where the CMA GEM object was mapped This function removes a buffer exported via DRM PRIME from the kernel's virtual address space. This is a no-op because CMA buffers cannot be unmapped from kernel space. Drivers using the CMA helpers should set this as their DRM driver's ->gem_prime_vunmap callback. Kernel Hackers Manual July 2017 struct drm_gem_cma_object 9 4.1.27 struct drm_gem_cma_object GEM object backed by CMA memory allocations struct drm_gem_cma_object { struct drm_gem_object base; dma_addr_t paddr; struct sg_table * sgt; void * vaddr; }; base base GEM object paddr physical address of the backing memory sgt scatter/gather table for imported PRIME buffers vaddr kernel virtual address of the backing memory Drivers must initialize the mode setting core by calling drm_mode_config_init on the DRM device. The function initializes the drm_device mode_config field and never fails. Once done, mode configuration must be setup by initializing the following fields. int min_width, min_height; int max_width, max_height; Minimum and maximum width and height of the frame buffers in pixel units. struct drm_mode_config_funcs *funcs; Mode setting functions. Kernel Hackers Manual July 2017 drm_mode_is_stereo 9 4.1.27 drm_mode_is_stereo check for stereo mode flags bool drm_mode_is_stereo const struct drm_display_mode * mode mode drm_display_mode to check True if the mode is one of the stereo modes (like side-by-side), false if not. Kernel Hackers Manual July 2017 drm_mode_debug_printmodeline 9 4.1.27 drm_mode_debug_printmodeline print a mode to dmesg void drm_mode_debug_printmodeline const struct drm_display_mode * mode mode mode to print Describe mode using DRM_DEBUG. Kernel Hackers Manual July 2017 drm_mode_create 9 4.1.27 drm_mode_create create a new display mode struct drm_display_mode * drm_mode_create struct drm_device * dev dev DRM device Create a new, cleared drm_display_mode with kzalloc, allocate an ID for it and return it. Pointer to new mode on success, NULL on error. Kernel Hackers Manual July 2017 drm_mode_destroy 9 4.1.27 drm_mode_destroy remove a mode void drm_mode_destroy struct drm_device * dev struct drm_display_mode * mode dev DRM device mode mode to remove Release mode's unique ID, then free it mode structure itself using kfree. Kernel Hackers Manual July 2017 drm_mode_probed_add 9 4.1.27 drm_mode_probed_add add a mode to a connector's probed_mode list void drm_mode_probed_add struct drm_connector * connector struct drm_display_mode * mode connector connector the new mode mode mode data Add mode to connector's probed_mode list for later use. This list should then in a second step get filtered and all the modes actually supported by the hardware moved to the connector's modes list. Kernel Hackers Manual July 2017 drm_cvt_mode 9 4.1.27 drm_cvt_mode create a modeline based on the CVT algorithm struct drm_display_mode * drm_cvt_mode struct drm_device * dev int hdisplay int vdisplay int vrefresh bool reduced bool interlaced bool margins dev drm device hdisplay hdisplay size vdisplay vdisplay size vrefresh vrefresh rate reduced whether to use reduced blanking interlaced whether to compute an interlaced mode margins whether to add margins (borders) This function is called to generate the modeline based on CVT algorithm according to the hdisplay, vdisplay, vrefresh. It is based from the VESA(TM) Coordinated Video Timing Generator by Graham Loveridge April 9, 2003 available at //www.elo.utfsm.cl/~elo212/docs/CVTd6r1.xls And it is copied from xf86CVTmode in xserver/hw/xfree86/modes/xf86cvt.c. What I have done is to translate it by using integer calculation. The modeline based on the CVT algorithm stored in a drm_display_mode object. The display mode object is allocated with drm_mode_create. Returns NULL when no mode could be allocated. Kernel Hackers Manual July 2017 drm_gtf_mode_complex 9 4.1.27 drm_gtf_mode_complex create the modeline based on the full GTF algorithm struct drm_display_mode * drm_gtf_mode_complex struct drm_device * dev int hdisplay int vdisplay int vrefresh bool interlaced int margins int GTF_M int GTF_2C int GTF_K int GTF_2J dev drm device hdisplay hdisplay size vdisplay vdisplay size vrefresh vrefresh rate. interlaced whether to compute an interlaced mode margins desired margin (borders) size GTF_M extended GTF formula parameters GTF_2C extended GTF formula parameters GTF_K extended GTF formula parameters GTF_2J extended GTF formula parameters GTF feature blocks specify C and J in multiples of 0.5, so we pass them in here multiplied by two. For a C of 40, pass in 80. The modeline based on the full GTF algorithm stored in a drm_display_mode object. The display mode object is allocated with drm_mode_create. Returns NULL when no mode could be allocated. Kernel Hackers Manual July 2017 drm_gtf_mode 9 4.1.27 drm_gtf_mode create the modeline based on the GTF algorithm struct drm_display_mode * drm_gtf_mode struct drm_device * dev int hdisplay int vdisplay int vrefresh bool interlaced int margins dev drm device hdisplay hdisplay size vdisplay vdisplay size vrefresh vrefresh rate. interlaced whether to compute an interlaced mode margins desired margin (borders) size return the modeline based on GTF algorithm This function is to create the modeline based on the GTF algorithm. GTF Spreadsheet by Andy Morrish (1/5/97) //www.vesa.org And it is copied from the file of xserver/hw/xfree86/modes/xf86gtf.c. What I have done is to translate it by using integer calculation. I also refer to the function of fb_get_mode in the file of drivers/video/fbmon.c M = 600 C = 40 K = 128 J = 20 The modeline based on the GTF algorithm stored in a drm_display_mode object. The display mode object is allocated with drm_mode_create. Returns NULL when no mode could be allocated. Kernel Hackers Manual July 2017 drm_display_mode_from_videomode 9 4.1.27 drm_display_mode_from_videomode fill in dmode using vm, void drm_display_mode_from_videomode const struct videomode * vm struct drm_display_mode * dmode vm videomode structure to use as source dmode drm_display_mode structure to use as destination Fills out dmode using the display mode specified in vm. Kernel Hackers Manual July 2017 drm_display_mode_to_videomode 9 4.1.27 drm_display_mode_to_videomode fill in vm using dmode, void drm_display_mode_to_videomode const struct drm_display_mode * dmode struct videomode * vm dmode drm_display_mode structure to use as source vm videomode structure to use as destination Fills out vm using the display mode specified in dmode. Kernel Hackers Manual July 2017 of_get_drm_display_mode 9 4.1.27 of_get_drm_display_mode get a drm_display_mode from devicetree int of_get_drm_display_mode struct device_node * np struct drm_display_mode * dmode int index np device_node with the timing specification dmode will be set to the return value index index into the list of display timings in devicetree This function is expensive and should only be used, if only one mode is to be read from DT. To get multiple modes start with of_get_display_timings and work with that instead. 0 on success, a negative errno code when no of videomode node was found. Kernel Hackers Manual July 2017 drm_mode_set_name 9 4.1.27 drm_mode_set_name set the name on a mode void drm_mode_set_name struct drm_display_mode * mode mode name will be set in this mode Set the name of mode to a standard format which is <hdisplay>x<vdisplay> with an optional 'i' suffix for interlaced modes. Kernel Hackers Manual July 2017 drm_mode_vrefresh 9 4.1.27 drm_mode_vrefresh get the vrefresh of a mode int drm_mode_vrefresh const struct drm_display_mode * mode mode mode modes's vrefresh rate in Hz, rounded to the nearest integer. Calculates the value first if it is not yet set. Kernel Hackers Manual July 2017 drm_mode_set_crtcinfo 9 4.1.27 drm_mode_set_crtcinfo set CRTC modesetting timing parameters void drm_mode_set_crtcinfo struct drm_display_mode * p int adjust_flags p mode adjust_flags a combination of adjustment flags Setup the CRTC modesetting timing parameters for p, adjusting if necessary. - The CRTC_INTERLACE_HALVE_V flag can be used to halve vertical timings of interlaced modes. - The CRTC_STEREO_DOUBLE flag can be used to compute the timings for buffers containing two eyes (only adjust the timings when needed, eg. for frame packing or side by side full). - The CRTC_NO_DBLSCAN and CRTC_NO_VSCAN flags request that adjustment *not* be performed for doublescan and vscan > 1 modes respectively. Kernel Hackers Manual July 2017 drm_mode_copy 9 4.1.27 drm_mode_copy copy the mode void drm_mode_copy struct drm_display_mode * dst const struct drm_display_mode * src dst mode to overwrite src mode to copy Copy an existing mode into another mode, preserving the object id and list head of the destination mode. Kernel Hackers Manual July 2017 drm_mode_duplicate 9 4.1.27 drm_mode_duplicate allocate and duplicate an existing mode struct drm_display_mode * drm_mode_duplicate struct drm_device * dev const struct drm_display_mode * mode dev drm_device to allocate the duplicated mode for mode mode to duplicate Just allocate a new mode, copy the existing mode into it, and return a pointer to it. Used to create new instances of established modes. Pointer to duplicated mode on success, NULL on error. Kernel Hackers Manual July 2017 drm_mode_equal 9 4.1.27 drm_mode_equal test modes for equality bool drm_mode_equal const struct drm_display_mode * mode1 const struct drm_display_mode * mode2 mode1 first mode mode2 second mode Check to see if mode1 and mode2 are equivalent. True if the modes are equal, false otherwise. Kernel Hackers Manual July 2017 drm_mode_equal_no_clocks_no_stereo 9 4.1.27 drm_mode_equal_no_clocks_no_stereo test modes for equality bool drm_mode_equal_no_clocks_no_stereo const struct drm_display_mode * mode1 const struct drm_display_mode * mode2 mode1 first mode mode2 second mode Check to see if mode1 and mode2 are equivalent, but don't check the pixel clocks nor the stereo layout. True if the modes are equal, false otherwise. Kernel Hackers Manual July 2017 drm_mode_validate_basic 9 4.1.27 drm_mode_validate_basic make sure the mode is somewhat sane enum drm_mode_status drm_mode_validate_basic const struct drm_display_mode * mode mode mode to check Check that the mode timings are at least somewhat reasonable. Any hardware specific limits are left up for each driver to check. The mode status Kernel Hackers Manual July 2017 drm_mode_validate_size 9 4.1.27 drm_mode_validate_size make sure modes adhere to size constraints enum drm_mode_status drm_mode_validate_size const struct drm_display_mode * mode int maxX int maxY mode mode to check maxX maximum width maxY maximum height This function is a helper which can be used to validate modes against size limitations of the DRM device/connector. If a mode is too big its status member is updated with the appropriate validation failure code. The list itself is not changed. The mode status Kernel Hackers Manual July 2017 drm_mode_prune_invalid 9 4.1.27 drm_mode_prune_invalid remove invalid modes from mode list void drm_mode_prune_invalid struct drm_device * dev struct list_head * mode_list bool verbose dev DRM device mode_list list of modes to check verbose be verbose about it This helper function can be used to prune a display mode list after validation has been completed. All modes who's status is not MODE_OK will be removed from the list, and if verbose the status code and mode name is also printed to dmesg. Kernel Hackers Manual July 2017 drm_mode_sort 9 4.1.27 drm_mode_sort sort mode list void drm_mode_sort struct list_head * mode_list mode_list list of drm_display_mode structures to sort Sort mode_list by favorability, moving good modes to the head of the list. Kernel Hackers Manual July 2017 drm_mode_connector_list_update 9 4.1.27 drm_mode_connector_list_update update the mode list for the connector void drm_mode_connector_list_update struct drm_connector * connector bool merge_type_bits connector the connector to update merge_type_bits whether to merge or overwrite type bits This moves the modes from the connector probed_modes list to the actual mode list. It compares the probed mode against the current list and only adds different/new modes. This is just a helper functions doesn't validate any modes itself and also doesn't prune any invalid modes. Callers need to do that themselves. Kernel Hackers Manual July 2017 drm_mode_parse_command_line_for_connector 9 4.1.27 drm_mode_parse_command_line_for_connector parse command line modeline for connector bool drm_mode_parse_command_line_for_connector const char * mode_option struct drm_connector * connector struct drm_cmdline_mode * mode mode_option optional per connector mode option connector connector to parse modeline for mode preallocated drm_cmdline_mode structure to fill out This parses mode_option command line modeline for modes and options to configure the connector. If mode_option is NULL the default command line modeline in fb_mode_option will be parsed instead. This uses the same parameters as the fb modedb.c, except for an extra force-enable, force-enable-digital and force-disable bit at the end: <xres>x<yres>[M][R][-<bpp>][@<refresh>][i][m][eDd] The intermediate drm_cmdline_mode structure is required to store additional options from the command line modline like the force-enable/disable flag. True if a valid modeline has been parsed, false otherwise. Kernel Hackers Manual July 2017 drm_mode_create_from_cmdline_mode 9 4.1.27 drm_mode_create_from_cmdline_mode convert a command line modeline into a DRM display mode struct drm_display_mode * drm_mode_create_from_cmdline_mode struct drm_device * dev struct drm_cmdline_mode * cmd dev DRM device to create the new mode for cmd input command line modeline Pointer to converted mode on success, NULL on error. Kernel Hackers Manual July 2017 drm_atomic_state_alloc 9 4.1.27 drm_atomic_state_alloc allocate atomic state struct drm_atomic_state * drm_atomic_state_alloc struct drm_device * dev dev DRM device This allocates an empty atomic state to track updates. Kernel Hackers Manual July 2017 drm_atomic_state_clear 9 4.1.27 drm_atomic_state_clear clear state object void drm_atomic_state_clear struct drm_atomic_state * state state atomic state When the w/w mutex algorithm detects a deadlock we need to back off and drop all locks. So someone else could sneak in and change the current modeset configuration. Which means that all the state assembled in state is no longer an atomic update to the current state, but to some arbitrary earlier state. Which could break assumptions the driver's ->atomic_check likely relies on. Hence we must clear all cached state and completely start over, using this function. Kernel Hackers Manual July 2017 drm_atomic_state_free 9 4.1.27 drm_atomic_state_free free all memory for an atomic state void drm_atomic_state_free struct drm_atomic_state * state state atomic state to deallocate This frees all memory associated with an atomic state, including all the per-object state for planes, crtcs and connectors. Kernel Hackers Manual July 2017 drm_atomic_get_crtc_state 9 4.1.27 drm_atomic_get_crtc_state get crtc state struct drm_crtc_state * drm_atomic_get_crtc_state struct drm_atomic_state * state struct drm_crtc * crtc state global atomic state object crtc crtc to get state object for This function returns the crtc state for the given crtc, allocating it if needed. It will also grab the relevant crtc lock to make sure that the state is consistent. Either the allocated state or the error code encoded into the pointer. When the error is EDEADLK then the w/w mutex code has detected a deadlock and the entire atomic sequence must be restarted. All other errors are fatal. Kernel Hackers Manual July 2017 drm_atomic_crtc_set_property 9 4.1.27 drm_atomic_crtc_set_property set property on CRTC int drm_atomic_crtc_set_property struct drm_crtc * crtc struct drm_crtc_state * state struct drm_property * property uint64_t val crtc the drm CRTC to set a property on state the state object to update with the new property value property the property to set val the new property value Use this instead of calling crtc->atomic_set_property directly. This function handles generic/core properties and calls out to driver's ->atomic_set_property for driver properties. To ensure consistent behavior you must call this function rather than the driver hook directly. Zero on success, error code on failure Kernel Hackers Manual July 2017 drm_atomic_get_plane_state 9 4.1.27 drm_atomic_get_plane_state get plane state struct drm_plane_state * drm_atomic_get_plane_state struct drm_atomic_state * state struct drm_plane * plane state global atomic state object plane plane to get state object for This function returns the plane state for the given plane, allocating it if needed. It will also grab the relevant plane lock to make sure that the state is consistent. Either the allocated state or the error code encoded into the pointer. When the error is EDEADLK then the w/w mutex code has detected a deadlock and the entire atomic sequence must be restarted. All other errors are fatal. Kernel Hackers Manual July 2017 drm_atomic_plane_set_property 9 4.1.27 drm_atomic_plane_set_property set property on plane int drm_atomic_plane_set_property struct drm_plane * plane struct drm_plane_state * state struct drm_property * property uint64_t val plane the drm plane to set a property on state the state object to update with the new property value property the property to set val the new property value Use this instead of calling plane->atomic_set_property directly. This function handles generic/core properties and calls out to driver's ->atomic_set_property for driver properties. To ensure consistent behavior you must call this function rather than the driver hook directly. Zero on success, error code on failure Kernel Hackers Manual July 2017 drm_atomic_get_connector_state 9 4.1.27 drm_atomic_get_connector_state get connector state struct drm_connector_state * drm_atomic_get_connector_state struct drm_atomic_state * state struct drm_connector * connector state global atomic state object connector connector to get state object for This function returns the connector state for the given connector, allocating it if needed. It will also grab the relevant connector lock to make sure that the state is consistent. Either the allocated state or the error code encoded into the pointer. When the error is EDEADLK then the w/w mutex code has detected a deadlock and the entire atomic sequence must be restarted. All other errors are fatal. Kernel Hackers Manual July 2017 drm_atomic_connector_set_property 9 4.1.27 drm_atomic_connector_set_property set property on connector. int drm_atomic_connector_set_property struct drm_connector * connector struct drm_connector_state * state struct drm_property * property uint64_t val connector the drm connector to set a property on state the state object to update with the new property value property the property to set val the new property value Use this instead of calling connector->atomic_set_property directly. This function handles generic/core properties and calls out to driver's ->atomic_set_property for driver properties. To ensure consistent behavior you must call this function rather than the driver hook directly. Zero on success, error code on failure Kernel Hackers Manual July 2017 drm_atomic_set_crtc_for_plane 9 4.1.27 drm_atomic_set_crtc_for_plane set crtc for plane int drm_atomic_set_crtc_for_plane struct drm_plane_state * plane_state struct drm_crtc * crtc plane_state the plane whose incoming state to update crtc crtc to use for the plane Changing the assigned crtc for a plane requires us to grab the lock and state for the new crtc, as needed. This function takes care of all these details besides updating the pointer in the state object itself. 0 on success or can fail with -EDEADLK or -ENOMEM. When the error is EDEADLK then the w/w mutex code has detected a deadlock and the entire atomic sequence must be restarted. All other errors are fatal. Kernel Hackers Manual July 2017 drm_atomic_set_fb_for_plane 9 4.1.27 drm_atomic_set_fb_for_plane set framebuffer for plane void drm_atomic_set_fb_for_plane struct drm_plane_state * plane_state struct drm_framebuffer * fb plane_state atomic state object for the plane fb fb to use for the plane Changing the assigned framebuffer for a plane requires us to grab a reference to the new fb and drop the reference to the old fb, if there is one. This function takes care of all these details besides updating the pointer in the state object itself. Kernel Hackers Manual July 2017 drm_atomic_set_crtc_for_connector 9 4.1.27 drm_atomic_set_crtc_for_connector set crtc for connector int drm_atomic_set_crtc_for_connector struct drm_connector_state * conn_state struct drm_crtc * crtc conn_state atomic state object for the connector crtc crtc to use for the connector Changing the assigned crtc for a connector requires us to grab the lock and state for the new crtc, as needed. This function takes care of all these details besides updating the pointer in the state object itself. 0 on success or can fail with -EDEADLK or -ENOMEM. When the error is EDEADLK then the w/w mutex code has detected a deadlock and the entire atomic sequence must be restarted. All other errors are fatal. Kernel Hackers Manual July 2017 drm_atomic_add_affected_connectors 9 4.1.27 drm_atomic_add_affected_connectors add connectors for crtc int drm_atomic_add_affected_connectors struct drm_atomic_state * state struct drm_crtc * crtc state atomic state crtc DRM crtc This function walks the current configuration and adds all connectors currently using crtc to the atomic configuration state. Note that this function must acquire the connection mutex. This can potentially cause unneeded seralization if the update is just for the planes on one crtc. Hence drivers and helpers should only call this when really needed (e.g. when a full modeset needs to happen due to some change). 0 on success or can fail with -EDEADLK or -ENOMEM. When the error is EDEADLK then the w/w mutex code has detected a deadlock and the entire atomic sequence must be restarted. All other errors are fatal. Kernel Hackers Manual July 2017 drm_atomic_connectors_for_crtc 9 4.1.27 drm_atomic_connectors_for_crtc count number of connected outputs int drm_atomic_connectors_for_crtc struct drm_atomic_state * state struct drm_crtc * crtc state atomic state crtc DRM crtc This function counts all connectors which will be connected to crtc according to state. Useful to recompute the enable state for crtc. Kernel Hackers Manual July 2017 drm_atomic_legacy_backoff 9 4.1.27 drm_atomic_legacy_backoff locking backoff for legacy ioctls void drm_atomic_legacy_backoff struct drm_atomic_state * state state atomic state This function should be used by legacy entry points which don't understand -EDEADLK semantics. For simplicity this one will grab all modeset locks after the slowpath completed. Kernel Hackers Manual July 2017 drm_atomic_check_only 9 4.1.27 drm_atomic_check_only check whether a given config would work int drm_atomic_check_only struct drm_atomic_state * state state atomic configuration to check Note that this function can return -EDEADLK if the driver needed to acquire more locks but encountered a deadlock. The caller must then do the usual w/w backoff dance and restart. All other errors are fatal. 0 on success, negative error code on failure. Kernel Hackers Manual July 2017 drm_atomic_commit 9 4.1.27 drm_atomic_commit commit configuration atomically int drm_atomic_commit struct drm_atomic_state * state state atomic configuration to check Note that this function can return -EDEADLK if the driver needed to acquire more locks but encountered a deadlock. The caller must then do the usual w/w backoff dance and restart. All other errors are fatal. Also note that on successful execution ownership of state is transferred from the caller of this function to the function itself. The caller must not free or in any other way access state. If the function fails then the caller must clean up state itself. 0 on success, negative error code on failure. Kernel Hackers Manual July 2017 drm_atomic_async_commit 9 4.1.27 drm_atomic_async_commit atomicasync configuration commit int drm_atomic_async_commit struct drm_atomic_state * state state atomic configuration to check Note that this function can return -EDEADLK if the driver needed to acquire more locks but encountered a deadlock. The caller must then do the usual w/w backoff dance and restart. All other errors are fatal. Also note that on successful execution ownership of state is transferred from the caller of this function to the function itself. The caller must not free or in any other way access state. If the function fails then the caller must clean up state itself. 0 on success, negative error code on failure. struct drm_framebuffer *(*fb_create)(struct drm_device *dev, struct drm_file *file_priv, struct drm_mode_fb_cmd2 *mode_cmd); Frame buffers are abstract memory objects that provide a source of pixels to scanout to a CRTC. Applications explicitly request the creation of frame buffers through the DRM_IOCTL_MODE_ADDFB(2) ioctls and receive an opaque handle that can be passed to the KMS CRTC control, plane configuration and page flip functions. Frame buffers rely on the underneath memory manager for low-level memory operations. When creating a frame buffer applications pass a memory handle (or a list of memory handles for multi-planar formats) through the drm_mode_fb_cmd2 argument. For drivers using GEM as their userspace buffer management interface this would be a GEM handle. Drivers are however free to use their own backing storage object handles, e.g. vmwgfx directly exposes special TTM handles to userspace and so expects TTM handles in the create ioctl and not GEM handles. Drivers must first validate the requested frame buffer parameters passed through the mode_cmd argument. In particular this is where invalid sizes, pixel formats or pitches can be caught. If the parameters are deemed valid, drivers then create, initialize and return an instance of struct drm_framebuffer. If desired the instance can be embedded in a larger driver-specific structure. Drivers must fill its width, height, pitches, offsets, depth, bits_per_pixel and pixel_format fields from the values passed through the drm_mode_fb_cmd2 argument. They should call the drm_helper_mode_fill_fb_struct helper function to do so. The initialization of the new framebuffer instance is finalized with a call to drm_framebuffer_init which takes a pointer to DRM frame buffer operations (struct drm_framebuffer_funcs). Note that this function publishes the framebuffer and so from this point on it can be accessed concurrently from other threads. Hence it must be the last step in the driver's framebuffer initialization sequence. Frame buffer operations are int (*create_handle)(struct drm_framebuffer *fb, struct drm_file *file_priv, unsigned int *handle); Create a handle to the frame buffer underlying memory object. If the frame buffer uses a multi-plane format, the handle will reference the memory object associated with the first plane. Drivers call drm_gem_handle_create to create the handle. void (*destroy)(struct drm_framebuffer *framebuffer); Destroy the frame buffer object and frees all associated resources. Drivers must call drm_framebuffer_cleanup to free resources allocated by the DRM core for the frame buffer object, and must make sure to unreference all memory objects associated with the frame buffer. Handles created by the create_handle operation are released by the DRM core. int (*dirty)(struct drm_framebuffer *framebuffer, struct drm_file *file_priv, unsigned flags, unsigned color, struct drm_clip_rect *clips, unsigned num_clips); This optional operation notifies the driver that a region of the frame buffer has changed in response to a DRM_IOCTL_MODE_DIRTYFB ioctl call. The lifetime of a drm framebuffer is controlled with a reference count, drivers can grab additional references with drm_framebuffer_referenceand drop them again with drm_framebuffer_unreference. For driver-private framebuffers for which the last reference is never dropped (e.g. for the fbdev framebuffer when the struct drm_framebuffer is embedded into the fbdev helper struct) drivers can manually clean up a framebuffer at module unload time with drm_framebuffer_unregister_private. The KMS API doesn't standardize backing storage object creation and leaves it to driver-specific ioctls. Furthermore actually creating a buffer object even for GEM-based drivers is done through a driver-specific ioctl - GEM only has a common userspace interface for sharing and destroying objects. While not an issue for full-fledged graphics stacks that include device-specific userspace components (in libdrm for instance), this limit makes DRM-based early boot graphics unnecessarily complex. Dumb objects partly alleviate the problem by providing a standard API to create dumb buffers suitable for scanout, which can then be used to create KMS frame buffers. To support dumb objects drivers must implement the dumb_create, dumb_destroy and dumb_map_offset operations. int (*dumb_create)(struct drm_file *file_priv, struct drm_device *dev, struct drm_mode_create_dumb *args); The dumb_create operation creates a driver object (GEM or TTM handle) suitable for scanout based on the width, height and depth from the struct drm_mode_create_dumb argument. It fills the argument's handle, pitch and size fields with a handle for the newly created object and its line pitch and size in bytes. int (*dumb_destroy)(struct drm_file *file_priv, struct drm_device *dev, uint32_t handle); The dumb_destroy operation destroys a dumb object created by dumb_create. int (*dumb_map_offset)(struct drm_file *file_priv, struct drm_device *dev, uint32_t handle, uint64_t *offset); The dumb_map_offset operation associates an mmap fake offset with the object given by the handle and returns it. Drivers must use the drm_gem_create_mmap_offset function to associate the fake offset as described in . Note that dumb objects may not be used for gpu acceleration, as has been attempted on some ARM embedded platforms. Such drivers really must have a hardware-specific ioctl to allocate suitable buffer objects. void (*output_poll_changed)(struct drm_device *dev); This operation notifies the driver that the status of one or more connectors has changed. Drivers that use the fb helper can just call the drm_fb_helper_hotplug_event function to handle this operation. Beside some lookup structures with their own locking (which is hidden behind the interface functions) most of the modeset state is protected by the dev-<mode_config.lock mutex and additionally per-crtc locks to allow cursor updates, pageflips and similar operations to occur concurrently with background tasks like output detection. Operations which cross domains like a full modeset always grab all locks. Drivers there need to protect resources shared between crtcs with additional locking. They also need to be careful to always grab the relevant crtc locks if a modset functions touches crtc state, e.g. for load detection (which does only grab the mode_config.lock to allow concurrent screen updates on live crtcs). A KMS device is abstracted and exposed as a set of planes, CRTCs, encoders and connectors. KMS drivers must thus create and initialize all those objects at load time after initializing mode setting. A CRTC is an abstraction representing a part of the chip that contains a pointer to a scanout buffer. Therefore, the number of CRTCs available determines how many independent scanout buffers can be active at any given time. The CRTC structure contains several fields to support this: a pointer to some video memory (abstracted as a frame buffer object), a display mode, and an (x, y) offset into the video memory to support panning or configurations where one piece of video memory spans multiple CRTCs. A KMS device must create and register at least one struct drm_crtc instance. The instance is allocated and zeroed by the driver, possibly as part of a larger structure, and registered with a call to drm_crtc_init with a pointer to CRTC functions. int (*set_config)(struct drm_mode_set *set); Apply a new CRTC configuration to the device. The configuration specifies a CRTC, a frame buffer to scan out from, a (x,y) position in the frame buffer, a display mode and an array of connectors to drive with the CRTC if possible. If the frame buffer specified in the configuration is NULL, the driver must detach all encoders connected to the CRTC and all connectors attached to those encoders and disable them. This operation is called with the mode config lock held. Note that the drm core has no notion of restoring the mode setting state after resume, since all resume handling is in the full responsibility of the driver. The common mode setting helper library though provides a helper which can be used for this: drm_helper_resume_force_mode. int (*page_flip)(struct drm_crtc *crtc, struct drm_framebuffer *fb, struct drm_pending_vblank_event *event); Schedule a page flip to the given frame buffer for the CRTC. This operation is called with the mode config mutex held. Page flipping is a synchronization mechanism that replaces the frame buffer being scanned out by the CRTC with a new frame buffer during vertical blanking, avoiding tearing. When an application requests a page flip the DRM core verifies that the new frame buffer is large enough to be scanned out by the CRTC in the currently configured mode and then calls the CRTC page_flip operation with a pointer to the new frame buffer. The page_flip operation schedules a page flip. Once any pending rendering targeting the new frame buffer has completed, the CRTC will be reprogrammed to display that frame buffer after the next vertical refresh. The operation must return immediately without waiting for rendering or page flip to complete and must block any new rendering to the frame buffer until the page flip completes. If a page flip can be successfully scheduled the driver must set the drm_crtc->fb field to the new framebuffer pointed to by fb. This is important so that the reference counting on framebuffers stays balanced. If a page flip is already pending, the page_flip operation must return -EBUSY. To synchronize page flip to vertical blanking the driver will likely need to enable vertical blanking interrupts. It should call drm_vblank_get for that purpose, and call drm_vblank_put after the page flip completes. If the application has requested to be notified when page flip completes the page_flip operation will be called with a non-NULL event argument pointing to a drm_pending_vblank_event instance. Upon page flip completion the driver must call drm_send_vblank_event to fill in the event and send to wake up any waiting processes. This can be performed with event_lock, flags); ... drm_send_vblank_event(dev, pipe, event); spin_unlock_irqrestore(&dev->event_lock, flags); ]]> FIXME: Could drivers that don't need to wait for rendering to complete just add the event to dev->vblank_event_list and let the DRM core handle everything, as for "normal" vertical blanking events? While waiting for the page flip to complete, the event->base.link list head can be used freely by the driver to store the pending event in a driver-specific list. If the file handle is closed before the event is signaled, drivers must take care to destroy the event in their preclose operation (and, if needed, call drm_vblank_put). void (*set_property)(struct drm_crtc *crtc, struct drm_property *property, uint64_t value); Set the value of the given CRTC property to value. See for more information about properties. void (*gamma_set)(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b, uint32_t start, uint32_t size); Apply a gamma table to the device. The operation is optional. void (*destroy)(struct drm_crtc *crtc); Destroy the CRTC when not needed anymore. See . A plane represents an image source that can be blended with or overlayed on top of a CRTC during the scanout process. Planes are associated with a frame buffer to crop a portion of the image memory (source) and optionally scale it to a destination size. The result is then blended with or overlayed on top of a CRTC. The DRM core recognizes three types of planes: DRM_PLANE_TYPE_PRIMARY represents a "main" plane for a CRTC. Primary planes are the planes operated upon by CRTC modesetting and flipping operations described in . DRM_PLANE_TYPE_CURSOR represents a "cursor" plane for a CRTC. Cursor planes are the planes operated upon by the DRM_IOCTL_MODE_CURSOR and DRM_IOCTL_MODE_CURSOR2 ioctls. DRM_PLANE_TYPE_OVERLAY represents all non-primary, non-cursor planes. Some drivers refer to these types of planes as "sprites" internally. For compatibility with legacy userspace, only overlay planes are made available to userspace by default. Userspace clients may set the DRM_CLIENT_CAP_UNIVERSAL_PLANES client capability bit to indicate that they wish to receive a universal plane list containing all plane types. To create a plane, a KMS drivers allocates and zeroes an instances of struct drm_plane (possibly as part of a larger structure) and registers it with a call to drm_universal_plane_init. The function takes a bitmask of the CRTCs that can be associated with the plane, a pointer to the plane functions, a list of format supported formats, and the type of plane (primary, cursor, or overlay) being initialized. Cursor and overlay planes are optional. All drivers should provide one primary plane per CRTC (although this requirement may change in the future); drivers that do not wish to provide special handling for primary planes may make use of the helper functions described in to create and register a primary plane with standard capabilities. int (*update_plane)(struct drm_plane *plane, struct drm_crtc *crtc, struct drm_framebuffer *fb, int crtc_x, int crtc_y, unsigned int crtc_w, unsigned int crtc_h, uint32_t src_x, uint32_t src_y, uint32_t src_w, uint32_t src_h); Enable and configure the plane to use the given CRTC and frame buffer. The source rectangle in frame buffer memory coordinates is given by the src_x, src_y, src_w and src_h parameters (as 16.16 fixed point values). Devices that don't support subpixel plane coordinates can ignore the fractional part. The destination rectangle in CRTC coordinates is given by the crtc_x, crtc_y, crtc_w and crtc_h parameters (as integer values). Devices scale the source rectangle to the destination rectangle. If scaling is not supported, and the source rectangle size doesn't match the destination rectangle size, the driver must return a -EINVAL error. int (*disable_plane)(struct drm_plane *plane); Disable the plane. The DRM core calls this method in response to a DRM_IOCTL_MODE_SETPLANE ioctl call with the frame buffer ID set to 0. Disabled planes must not be processed by the CRTC. void (*destroy)(struct drm_plane *plane); Destroy the plane when not needed anymore. See . An encoder takes pixel data from a CRTC and converts it to a format suitable for any attached connectors. On some devices, it may be possible to have a CRTC send data to more than one encoder. In that case, both encoders would receive data from the same scanout buffer, resulting in a "cloned" display configuration across the connectors attached to each encoder. As for CRTCs, a KMS driver must create, initialize and register at least one struct drm_encoder instance. The instance is allocated and zeroed by the driver, possibly as part of a larger structure. Drivers must initialize the struct drm_encoder possible_crtcs and possible_clones fields before registering the encoder. Both fields are bitmasks of respectively the CRTCs that the encoder can be connected to, and sibling encoders candidate for cloning. After being initialized, the encoder must be registered with a call to drm_encoder_init. The function takes a pointer to the encoder functions and an encoder type. Supported types are DRM_MODE_ENCODER_DAC for VGA and analog on DVI-I/DVI-A DRM_MODE_ENCODER_TMDS for DVI, HDMI and (embedded) DisplayPort DRM_MODE_ENCODER_LVDS for display panels DRM_MODE_ENCODER_TVDAC for TV output (Composite, S-Video, Component, SCART) DRM_MODE_ENCODER_VIRTUAL for virtual machine displays Encoders must be attached to a CRTC to be used. DRM drivers leave encoders unattached at initialization time. Applications (or the fbdev compatibility layer when implemented) are responsible for attaching the encoders they want to use to a CRTC. void (*destroy)(struct drm_encoder *encoder); Called to destroy the encoder when not needed anymore. See . void (*set_property)(struct drm_plane *plane, struct drm_property *property, uint64_t value); Set the value of the given plane property to value. See for more information about properties. A connector is the final destination for pixel data on a device, and usually connects directly to an external display device like a monitor or laptop panel. A connector can only be attached to one encoder at a time. The connector is also the structure where information about the attached display is kept, so it contains fields for display data, EDID data, DPMS & connection status, and information about modes supported on the attached displays. Finally a KMS driver must create, initialize, register and attach at least one struct drm_connector instance. The instance is created as other KMS objects and initialized by setting the following fields. interlace_allowed Whether the connector can handle interlaced modes. doublescan_allowed Whether the connector can handle doublescan. display_info Display information is filled from EDID information when a display is detected. For non hot-pluggable displays such as flat panels in embedded systems, the driver should initialize the display_info.width_mm and display_info.height_mm fields with the physical size of the display. polled Connector polling mode, a combination of DRM_CONNECTOR_POLL_HPD The connector generates hotplug events and doesn't need to be periodically polled. The CONNECT and DISCONNECT flags must not be set together with the HPD flag. DRM_CONNECTOR_POLL_CONNECT Periodically poll the connector for connection. DRM_CONNECTOR_POLL_DISCONNECT Periodically poll the connector for disconnection. Set to 0 for connectors that don't support connection status discovery. The connector is then registered with a call to drm_connector_init with a pointer to the connector functions and a connector type, and exposed through sysfs with a call to drm_connector_register. Supported connector types are DRM_MODE_CONNECTOR_VGA DRM_MODE_CONNECTOR_DVII DRM_MODE_CONNECTOR_DVID DRM_MODE_CONNECTOR_DVIA DRM_MODE_CONNECTOR_Composite DRM_MODE_CONNECTOR_SVIDEO DRM_MODE_CONNECTOR_LVDS DRM_MODE_CONNECTOR_Component DRM_MODE_CONNECTOR_9PinDIN DRM_MODE_CONNECTOR_DisplayPort DRM_MODE_CONNECTOR_HDMIA DRM_MODE_CONNECTOR_HDMIB DRM_MODE_CONNECTOR_TV DRM_MODE_CONNECTOR_eDP DRM_MODE_CONNECTOR_VIRTUAL Connectors must be attached to an encoder to be used. For devices that map connectors to encoders 1:1, the connector should be attached at initialization time with a call to drm_mode_connector_attach_encoder. The driver must also set the drm_connector encoder field to point to the attached encoder. Finally, drivers must initialize the connectors state change detection with a call to drm_kms_helper_poll_init. If at least one connector is pollable but can't generate hotplug interrupts (indicated by the DRM_CONNECTOR_POLL_CONNECT and DRM_CONNECTOR_POLL_DISCONNECT connector flags), a delayed work will automatically be queued to periodically poll for changes. Connectors that can generate hotplug interrupts must be marked with the DRM_CONNECTOR_POLL_HPD flag instead, and their interrupt handler must call drm_helper_hpd_irq_event. The function will queue a delayed work to check the state of all connectors, but no periodic polling will be done. Unless otherwise state, all operations are mandatory. void (*dpms)(struct drm_connector *connector, int mode); The DPMS operation sets the power state of a connector. The mode argument is one of DRM_MODE_DPMS_ON DRM_MODE_DPMS_STANDBY DRM_MODE_DPMS_SUSPEND DRM_MODE_DPMS_OFF In all but DPMS_ON mode the encoder to which the connector is attached should put the display in low-power mode by driving its signals appropriately. If more than one connector is attached to the encoder care should be taken not to change the power state of other displays as a side effect. Low-power mode should be propagated to the encoders and CRTCs when all related connectors are put in low-power mode. int (*fill_modes)(struct drm_connector *connector, uint32_t max_width, uint32_t max_height); Fill the mode list with all supported modes for the connector. If the max_width and max_height arguments are non-zero, the implementation must ignore all modes wider than max_width or higher than max_height. The connector must also fill in this operation its display_info width_mm and height_mm fields with the connected display physical size in millimeters. The fields should be set to 0 if the value isn't known or is not applicable (for instance for projector devices). The connection status is updated through polling or hotplug events when supported (see ). The status value is reported to userspace through ioctls and must not be used inside the driver, as it only gets initialized by a call to drm_mode_getconnector from userspace. enum drm_connector_status (*detect)(struct drm_connector *connector, bool force); Check to see if anything is attached to the connector. The force parameter is set to false whilst polling or to true when checking the connector due to user request. force can be used by the driver to avoid expensive, destructive operations during automated probing. Return connector_status_connected if something is connected to the connector, connector_status_disconnected if nothing is connected and connector_status_unknown if the connection state isn't known. Drivers should only return connector_status_connected if the connection status has really been probed as connected. Connectors that can't detect the connection status, or failed connection status probes, should return connector_status_unknown. void (*set_property)(struct drm_connector *connector, struct drm_property *property, uint64_t value); Set the value of the given connector property to value. See for more information about properties. void (*destroy)(struct drm_connector *connector); Destroy the connector when not needed anymore. See . The DRM core manages its objects' lifetime. When an object is not needed anymore the core calls its destroy function, which must clean up and free every resource allocated for the object. Every drm_*_init call must be matched with a corresponding drm_*_cleanup call to cleanup CRTCs (drm_crtc_cleanup), planes (drm_plane_cleanup), encoders (drm_encoder_cleanup) and connectors (drm_connector_cleanup). Furthermore, connectors that have been added to sysfs must be removed by a call to drm_connector_unregister before calling drm_connector_cleanup. Connectors state change detection must be cleanup up with a call to drm_kms_helper_poll_fini. base; drm_connector_init(dev, &intel_output->base, &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA); drm_encoder_init(dev, &intel_output->enc, &intel_crt_enc_funcs, DRM_MODE_ENCODER_DAC); drm_mode_connector_attach_encoder(&intel_output->base, &intel_output->enc); /* Set up the DDC bus. */ intel_output->ddc_bus = intel_i2c_create(dev, GPIOA, "CRTDDC_A"); if (!intel_output->ddc_bus) { dev_printk(KERN_ERR, &dev->pdev->dev, "DDC bus registration " "failed.\n"); return; } intel_output->type = INTEL_OUTPUT_ANALOG; connector->interlace_allowed = 0; connector->doublescan_allowed = 0; drm_encoder_helper_add(&intel_output->enc, &intel_crt_helper_funcs); drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs); drm_connector_register(connector); }]]> In the example above (taken from the i915 driver), a CRTC, connector and encoder combination is created. A device-specific i2c bus is also created for fetching EDID data and performing monitor detection. Once the process is complete, the new connector is registered with sysfs to make its properties available to applications. Kernel Hackers Manual July 2017 drm_get_connector_status_name 9 4.1.27 drm_get_connector_status_name return a string for connector status const char * drm_get_connector_status_name enum drm_connector_status status status connector status to compute name of In contrast to the other drm_get_*_name functions this one here returns a const pointer and hence is threadsafe. Kernel Hackers Manual July 2017 drm_get_subpixel_order_name 9 4.1.27 drm_get_subpixel_order_name return a string for a given subpixel enum const char * drm_get_subpixel_order_name enum subpixel_order order order enum of subpixel_order Note you could abuse this and return something out of bounds, but that would be a caller error. No unscrubbed user data should make it here. Kernel Hackers Manual July 2017 drm_get_format_name 9 4.1.27 drm_get_format_name return a string for drm fourcc format const char * drm_get_format_name uint32_t format format format to compute name of Note that the buffer used by this function is globally shared and owned by the function itself. This isn't really multithreading safe. Kernel Hackers Manual July 2017 drm_mode_object_find 9 4.1.27 drm_mode_object_find look up a drm object with static lifetime struct drm_mode_object * drm_mode_object_find struct drm_device * dev uint32_t id uint32_t type dev drm device id id of the mode object type type of the mode object Note that framebuffers cannot be looked up with this functions - since those are reference counted, they need special treatment. Even with DRM_MODE_OBJECT_ANY (although that will simply return NULL rather than WARN_ON). Kernel Hackers Manual July 2017 drm_framebuffer_init 9 4.1.27 drm_framebuffer_init initialize a framebuffer int drm_framebuffer_init struct drm_device * dev struct drm_framebuffer * fb const struct drm_framebuffer_funcs * funcs dev DRM device fb framebuffer to be initialized funcs ... with these functions Allocates an ID for the framebuffer's parent mode object, sets its mode functions & device file and adds it to the master fd list. This functions publishes the fb and makes it available for concurrent access by other users. Which means by this point the fb _must_ be fully set up - since all the fb attributes are invariant over its lifetime, no further locking but only correct reference counting is required. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_framebuffer_lookup 9 4.1.27 drm_framebuffer_lookup look up a drm framebuffer and grab a reference struct drm_framebuffer * drm_framebuffer_lookup struct drm_device * dev uint32_t id dev drm device id id of the fb object If successful, this grabs an additional reference to the framebuffer - callers need to make sure to eventually unreference the returned framebuffer again, using drm_framebuffer_unreference. Kernel Hackers Manual July 2017 drm_framebuffer_unreference 9 4.1.27 drm_framebuffer_unreference unref a framebuffer void drm_framebuffer_unreference struct drm_framebuffer * fb fb framebuffer to unref This functions decrements the fb's refcount and frees it if it drops to zero. Kernel Hackers Manual July 2017 drm_framebuffer_reference 9 4.1.27 drm_framebuffer_reference incr the fb refcnt void drm_framebuffer_reference struct drm_framebuffer * fb fb framebuffer This functions increments the fb's refcount. Kernel Hackers Manual July 2017 drm_framebuffer_unregister_private 9 4.1.27 drm_framebuffer_unregister_private unregister a private fb from the lookup idr void drm_framebuffer_unregister_private struct drm_framebuffer * fb fb fb to unregister Drivers need to call this when cleaning up driver-private framebuffers, e.g. those used for fbdev. Note that the caller must hold a reference of it's own, i.e. the object may not be destroyed through this call (since it'll lead to a locking inversion). Kernel Hackers Manual July 2017 drm_framebuffer_cleanup 9 4.1.27 drm_framebuffer_cleanup remove a framebuffer object void drm_framebuffer_cleanup struct drm_framebuffer * fb fb framebuffer to remove Cleanup framebuffer. This function is intended to be used from the drivers ->destroy callback. It can also be used to clean up driver private framebuffers embedded into a larger structure. Note that this function does not remove the fb from active usuage - if it is still used anywhere, hilarity can ensue since userspace could call getfb on the id and get back -EINVAL. Obviously no concern at driver unload time. Also, the framebuffer will not be removed from the lookup idr - for user-created framebuffers this will happen in in the rmfb ioctl. For driver-private objects (e.g. for fbdev) drivers need to explicitly call drm_framebuffer_unregister_private. Kernel Hackers Manual July 2017 drm_framebuffer_remove 9 4.1.27 drm_framebuffer_remove remove and unreference a framebuffer object void drm_framebuffer_remove struct drm_framebuffer * fb fb framebuffer to remove Scans all the CRTCs and planes in dev's mode_config. If they're using fb, removes it, setting it to NULL. Then drops the reference to the passed-in framebuffer. Might take the modeset locks. Note that this function optimizes the cleanup away if the caller holds the last reference to the framebuffer. It is also guaranteed to not take the modeset locks in this case. Kernel Hackers Manual July 2017 drm_crtc_init_with_planes 9 4.1.27 drm_crtc_init_with_planes Initialise a new CRTC object with specified primary and cursor planes. int drm_crtc_init_with_planes struct drm_device * dev struct drm_crtc * crtc struct drm_plane * primary struct drm_plane * cursor const struct drm_crtc_funcs * funcs dev DRM device crtc CRTC object to init primary Primary plane for CRTC cursor Cursor plane for CRTC funcs callbacks for the new CRTC Inits a new object created as base part of a driver crtc object. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_crtc_cleanup 9 4.1.27 drm_crtc_cleanup Clean up the core crtc usage void drm_crtc_cleanup struct drm_crtc * crtc crtc CRTC to cleanup This function cleans up crtc and removes it from the DRM mode setting core. Note that the function does *not* free the crtc structure itself, this is the responsibility of the caller. Kernel Hackers Manual July 2017 drm_crtc_index 9 4.1.27 drm_crtc_index find the index of a registered CRTC unsigned int drm_crtc_index struct drm_crtc * crtc crtc CRTC to find index for Given a registered CRTC, return the index of that CRTC within a DRM device's list of CRTCs. Kernel Hackers Manual July 2017 drm_display_info_set_bus_formats 9 4.1.27 drm_display_info_set_bus_formats set the supported bus formats int drm_display_info_set_bus_formats struct drm_display_info * info const u32 * formats unsigned int num_formats info display info to store bus formats in formats array containing the supported bus formats num_formats the number of entries in the fmts array Store the supported bus formats in display info structure. See MEDIA_BUS_FMT_* definitions in include/uapi/linux/media-bus-format.h for a full list of available formats. Kernel Hackers Manual July 2017 drm_connector_init 9 4.1.27 drm_connector_init Init a preallocated connector int drm_connector_init struct drm_device * dev struct drm_connector * connector const struct drm_connector_funcs * funcs int connector_type dev DRM device connector the connector to init funcs callbacks for this connector connector_type user visible type of the connector Initialises a preallocated connector. Connectors should be subclassed as part of driver connector objects. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_connector_cleanup 9 4.1.27 drm_connector_cleanup cleans up an initialised connector void drm_connector_cleanup struct drm_connector * connector connector connector to cleanup Cleans up the connector but doesn't free the object. Kernel Hackers Manual July 2017 drm_connector_index 9 4.1.27 drm_connector_index find the index of a registered connector unsigned int drm_connector_index struct drm_connector * connector connector connector to find index for Given a registered connector, return the index of that connector within a DRM device's list of connectors. Kernel Hackers Manual July 2017 drm_connector_register 9 4.1.27 drm_connector_register register a connector int drm_connector_register struct drm_connector * connector connector the connector to register Register userspace interfaces for a connector Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_connector_unregister 9 4.1.27 drm_connector_unregister unregister a connector void drm_connector_unregister struct drm_connector * connector connector the connector to unregister Unregister userspace interfaces for a connector Kernel Hackers Manual July 2017 drm_connector_unplug_all 9 4.1.27 drm_connector_unplug_all unregister connector userspace interfaces void drm_connector_unplug_all struct drm_device * dev dev drm device This function unregisters all connector userspace interfaces in sysfs. Should be call when the device is disconnected, e.g. from an usb driver's ->disconnect callback. Kernel Hackers Manual July 2017 drm_encoder_init 9 4.1.27 drm_encoder_init Init a preallocated encoder int drm_encoder_init struct drm_device * dev struct drm_encoder * encoder const struct drm_encoder_funcs * funcs int encoder_type dev drm device encoder the encoder to init funcs callbacks for this encoder encoder_type user visible type of the encoder Initialises a preallocated encoder. Encoder should be subclassed as part of driver encoder objects. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_encoder_cleanup 9 4.1.27 drm_encoder_cleanup cleans up an initialised encoder void drm_encoder_cleanup struct drm_encoder * encoder encoder encoder to cleanup Cleans up the encoder but doesn't free the object. Kernel Hackers Manual July 2017 drm_universal_plane_init 9 4.1.27 drm_universal_plane_init Initialize a new universal plane object int drm_universal_plane_init struct drm_device * dev struct drm_plane * plane unsigned long possible_crtcs const struct drm_plane_funcs * funcs const uint32_t * formats uint32_t format_count enum drm_plane_type type dev DRM device plane plane object to init possible_crtcs bitmask of possible CRTCs funcs callbacks for the new plane formats array of supported formats (DRM_FORMAT_*) format_count number of elements in formats type type of plane (overlay, primary, cursor) Initializes a plane object of type type. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_plane_init 9 4.1.27 drm_plane_init Initialize a legacy plane int drm_plane_init struct drm_device * dev struct drm_plane * plane unsigned long possible_crtcs const struct drm_plane_funcs * funcs const uint32_t * formats uint32_t format_count bool is_primary dev DRM device plane plane object to init possible_crtcs bitmask of possible CRTCs funcs callbacks for the new plane formats array of supported formats (DRM_FORMAT_*) format_count number of elements in formats is_primary plane type (primary vs overlay) Legacy API to initialize a DRM plane. New drivers should call drm_universal_plane_init instead. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_plane_cleanup 9 4.1.27 drm_plane_cleanup Clean up the core plane usage void drm_plane_cleanup struct drm_plane * plane plane plane to cleanup This function cleans up plane and removes it from the DRM mode setting core. Note that the function does *not* free the plane structure itself, this is the responsibility of the caller. Kernel Hackers Manual July 2017 drm_plane_index 9 4.1.27 drm_plane_index find the index of a registered plane unsigned int drm_plane_index struct drm_plane * plane plane plane to find index for Given a registered plane, return the index of that CRTC within a DRM device's list of planes. Kernel Hackers Manual July 2017 drm_plane_force_disable 9 4.1.27 drm_plane_force_disable Forcibly disable a plane void drm_plane_force_disable struct drm_plane * plane plane plane to disable Forces the plane to be disabled. Used when the plane's current framebuffer is destroyed, and when restoring fbdev mode. Kernel Hackers Manual July 2017 drm_mode_create_dvi_i_properties 9 4.1.27 drm_mode_create_dvi_i_properties create DVI-I specific connector properties int drm_mode_create_dvi_i_properties struct drm_device * dev dev DRM device Called by a driver the first time a DVI-I connector is made. Kernel Hackers Manual July 2017 drm_mode_create_tv_properties 9 4.1.27 drm_mode_create_tv_properties create TV specific connector properties int drm_mode_create_tv_properties struct drm_device * dev unsigned int num_modes char * modes[] dev DRM device num_modes number of different TV formats (modes) supported modes[] array of pointers to strings containing name of each format Called by a driver's TV initialization routine, this function creates the TV specific connector properties for a given device. Caller is responsible for allocating a list of format names and passing them to this routine. Kernel Hackers Manual July 2017 drm_mode_create_scaling_mode_property 9 4.1.27 drm_mode_create_scaling_mode_property create scaling mode property int drm_mode_create_scaling_mode_property struct drm_device * dev dev DRM device Called by a driver the first time it's needed, must be attached to desired connectors. Kernel Hackers Manual July 2017 drm_mode_create_aspect_ratio_property 9 4.1.27 drm_mode_create_aspect_ratio_property create aspect ratio property int drm_mode_create_aspect_ratio_property struct drm_device * dev dev DRM device Called by a driver the first time it's needed, must be attached to desired connectors. Zero on success, negative errno on failure. Kernel Hackers Manual July 2017 drm_mode_create_dirty_info_property 9 4.1.27 drm_mode_create_dirty_info_property create dirty property int drm_mode_create_dirty_info_property struct drm_device * dev dev DRM device Called by a driver the first time it's needed, must be attached to desired connectors. Kernel Hackers Manual July 2017 drm_mode_create_suggested_offset_properties 9 4.1.27 drm_mode_create_suggested_offset_properties create suggests offset properties int drm_mode_create_suggested_offset_properties struct drm_device * dev dev DRM device Create the the suggested x/y offset property for connectors. Kernel Hackers Manual July 2017 drm_mode_set_config_internal 9 4.1.27 drm_mode_set_config_internal helper to call ->set_config int drm_mode_set_config_internal struct drm_mode_set * set set modeset config to set This is a little helper to wrap internal calls to the ->set_config driver interface. The only thing it adds is correct refcounting dance. Zero on success, negative errno on failure. Kernel Hackers Manual July 2017 drm_crtc_get_hv_timing 9 4.1.27 drm_crtc_get_hv_timing Fetches hdisplay/vdisplay for given mode void drm_crtc_get_hv_timing const struct drm_display_mode * mode int * hdisplay int * vdisplay mode mode to query hdisplay hdisplay value to fill in vdisplay vdisplay value to fill in The vdisplay value will be doubled if the specified mode is a stereo mode of the appropriate layout. Kernel Hackers Manual July 2017 drm_crtc_check_viewport 9 4.1.27 drm_crtc_check_viewport Checks that a framebuffer is big enough for the CRTC viewport int drm_crtc_check_viewport const struct drm_crtc * crtc int x int y const struct drm_display_mode * mode const struct drm_framebuffer * fb crtc CRTC that framebuffer will be displayed on x x panning y y panning mode mode that framebuffer will be displayed under fb framebuffer to check size of Kernel Hackers Manual July 2017 drm_mode_legacy_fb_format 9 4.1.27 drm_mode_legacy_fb_format compute drm fourcc code from legacy description uint32_t drm_mode_legacy_fb_format uint32_t bpp uint32_t depth bpp bits per pixels depth bit depth per pixel Computes a drm fourcc pixel format code for the given bpp/depth values. Useful in fbdev emulation code, since that deals in those values. Kernel Hackers Manual July 2017 drm_property_create 9 4.1.27 drm_property_create create a new property type struct drm_property * drm_property_create struct drm_device * dev int flags const char * name int num_values dev drm device flags flags specifying the property type name name of the property num_values number of pre-defined values This creates a new generic drm property which can then be attached to a drm object with drm_object_attach_property. The returned property object must be freed with drm_property_destroy. Note that the DRM core keeps a per-device list of properties and that, if drm_mode_config_cleanup is called, it will destroy all properties created by the driver. A pointer to the newly created property on success, NULL on failure. Kernel Hackers Manual July 2017 drm_property_create_enum 9 4.1.27 drm_property_create_enum create a new enumeration property type struct drm_property * drm_property_create_enum struct drm_device * dev int flags const char * name const struct drm_prop_enum_list * props int num_values dev drm device flags flags specifying the property type name name of the property props enumeration lists with property values num_values number of pre-defined values This creates a new generic drm property which can then be attached to a drm object with drm_object_attach_property. The returned property object must be freed with drm_property_destroy. Userspace is only allowed to set one of the predefined values for enumeration properties. A pointer to the newly created property on success, NULL on failure. Kernel Hackers Manual July 2017 drm_property_create_bitmask 9 4.1.27 drm_property_create_bitmask create a new bitmask property type struct drm_property * drm_property_create_bitmask struct drm_device * dev int flags const char * name const struct drm_prop_enum_list * props int num_props uint64_t supported_bits dev drm device flags flags specifying the property type name name of the property props enumeration lists with property bitflags num_props size of the props array supported_bits bitmask of all supported enumeration values This creates a new bitmask drm property which can then be attached to a drm object with drm_object_attach_property. The returned property object must be freed with drm_property_destroy. Compared to plain enumeration properties userspace is allowed to set any or'ed together combination of the predefined property bitflag values A pointer to the newly created property on success, NULL on failure. Kernel Hackers Manual July 2017 drm_property_create_range 9 4.1.27 drm_property_create_range create a new unsigned ranged property type struct drm_property * drm_property_create_range struct drm_device * dev int flags const char * name uint64_t min uint64_t max dev drm device flags flags specifying the property type name name of the property min minimum value of the property max maximum value of the property This creates a new generic drm property which can then be attached to a drm object with drm_object_attach_property. The returned property object must be freed with drm_property_destroy. Userspace is allowed to set any unsigned integer value in the (min, max) range inclusive. A pointer to the newly created property on success, NULL on failure. Kernel Hackers Manual July 2017 drm_property_create_signed_range 9 4.1.27 drm_property_create_signed_range create a new signed ranged property type struct drm_property * drm_property_create_signed_range struct drm_device * dev int flags const char * name int64_t min int64_t max dev drm device flags flags specifying the property type name name of the property min minimum value of the property max maximum value of the property This creates a new generic drm property which can then be attached to a drm object with drm_object_attach_property. The returned property object must be freed with drm_property_destroy. Userspace is allowed to set any signed integer value in the (min, max) range inclusive. A pointer to the newly created property on success, NULL on failure. Kernel Hackers Manual July 2017 drm_property_create_object 9 4.1.27 drm_property_create_object create a new object property type struct drm_property * drm_property_create_object struct drm_device * dev int flags const char * name uint32_t type dev drm device flags flags specifying the property type name name of the property type object type from DRM_MODE_OBJECT_* defines This creates a new generic drm property which can then be attached to a drm object with drm_object_attach_property. The returned property object must be freed with drm_property_destroy. Userspace is only allowed to set this to any property value of the given type. Only useful for atomic properties, which is enforced. A pointer to the newly created property on success, NULL on failure. Kernel Hackers Manual July 2017 drm_property_create_bool 9 4.1.27 drm_property_create_bool create a new boolean property type struct drm_property * drm_property_create_bool struct drm_device * dev int flags const char * name dev drm device flags flags specifying the property type name name of the property This creates a new generic drm property which can then be attached to a drm object with drm_object_attach_property. The returned property object must be freed with drm_property_destroy. This is implemented as a ranged property with only {0, 1} as valid values. A pointer to the newly created property on success, NULL on failure. Kernel Hackers Manual July 2017 drm_property_add_enum 9 4.1.27 drm_property_add_enum add a possible value to an enumeration property int drm_property_add_enum struct drm_property * property int index uint64_t value const char * name property enumeration property to change index index of the new enumeration value value of the new enumeration name symbolic name of the new enumeration This functions adds enumerations to a property. It's use is deprecated, drivers should use one of the more specific helpers to directly create the property with all enumerations already attached. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_property_destroy 9 4.1.27 drm_property_destroy destroy a drm property void drm_property_destroy struct drm_device * dev struct drm_property * property dev drm device property property to destry This function frees a property including any attached resources like enumeration values. Kernel Hackers Manual July 2017 drm_object_attach_property 9 4.1.27 drm_object_attach_property attach a property to a modeset object void drm_object_attach_property struct drm_mode_object * obj struct drm_property * property uint64_t init_val obj drm modeset object property property to attach init_val initial value of the property This attaches the given property to the modeset object with the given initial value. Currently this function cannot fail since the properties are stored in a statically sized array. Kernel Hackers Manual July 2017 drm_object_property_set_value 9 4.1.27 drm_object_property_set_value set the value of a property int drm_object_property_set_value struct drm_mode_object * obj struct drm_property * property uint64_t val obj drm mode object to set property value for property property to set val value the property should be set to This functions sets a given property on a given object. This function only changes the software state of the property, it does not call into the driver's ->set_property callback. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_object_property_get_value 9 4.1.27 drm_object_property_get_value retrieve the value of a property int drm_object_property_get_value struct drm_mode_object * obj struct drm_property * property uint64_t * val obj drm mode object to get property value from property property to retrieve val storage for the property value This function retrieves the softare state of the given property for the given property. Since there is no driver callback to retrieve the current property value this might be out of sync with the hardware, depending upon the driver and property. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_mode_connector_set_path_property 9 4.1.27 drm_mode_connector_set_path_property set tile property on connector int drm_mode_connector_set_path_property struct drm_connector * connector const char * path connector connector to set property on. path path to use for property. This creates a property to expose to userspace to specify a connector path. This is mainly used for DisplayPort MST where connectors have a topology and we want to allow userspace to give them more meaningful names. Zero on success, negative errno on failure. Kernel Hackers Manual July 2017 drm_mode_connector_set_tile_property 9 4.1.27 drm_mode_connector_set_tile_property set tile property on connector int drm_mode_connector_set_tile_property struct drm_connector * connector connector connector to set property on. This looks up the tile information for a connector, and creates a property for userspace to parse if it exists. The property is of the form of 8 integers using ':' as a separator. Zero on success, errno on failure. Kernel Hackers Manual July 2017 drm_mode_connector_update_edid_property 9 4.1.27 drm_mode_connector_update_edid_property update the edid property of a connector int drm_mode_connector_update_edid_property struct drm_connector * connector const struct edid * edid connector drm connector edid new value of the edid property This function creates a new blob modeset object and assigns its id to the connector's edid property. Zero on success, negative errno on failure. Kernel Hackers Manual July 2017 drm_mode_plane_set_obj_prop 9 4.1.27 drm_mode_plane_set_obj_prop set the value of a property int drm_mode_plane_set_obj_prop struct drm_plane * plane struct drm_property * property uint64_t value plane drm plane object to set property value for property property to set value value the property should be set to This functions sets a given property on a given plane object. This function calls the driver's ->set_property callback and changes the software state of the property if the callback succeeds. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_mode_connector_attach_encoder 9 4.1.27 drm_mode_connector_attach_encoder attach a connector to an encoder int drm_mode_connector_attach_encoder struct drm_connector * connector struct drm_encoder * encoder connector connector to attach encoder encoder to attach connector to This function links up a connector to an encoder. Note that the routing restrictions between encoders and crtcs are exposed to userspace through the possible_clones and possible_crtcs bitmasks. Zero on success, negative errno on failure. Kernel Hackers Manual July 2017 drm_mode_crtc_set_gamma_size 9 4.1.27 drm_mode_crtc_set_gamma_size set the gamma table size int drm_mode_crtc_set_gamma_size struct drm_crtc * crtc int gamma_size crtc CRTC to set the gamma table size for gamma_size size of the gamma table Drivers which support gamma tables should set this to the supported gamma table size when initializing the CRTC. Currently the drm core only supports a fixed gamma table size. Zero on success, negative errno on failure. Kernel Hackers Manual July 2017 drm_mode_config_reset 9 4.1.27 drm_mode_config_reset call ->reset callbacks void drm_mode_config_reset struct drm_device * dev dev drm device This functions calls all the crtc's, encoder's and connector's ->reset callback. Drivers can use this in e.g. their driver load or resume code to reset hardware and software state. Kernel Hackers Manual July 2017 drm_fb_get_bpp_depth 9 4.1.27 drm_fb_get_bpp_depth get the bpp/depth values for format void drm_fb_get_bpp_depth uint32_t format unsigned int * depth int * bpp format pixel format (DRM_FORMAT_*) depth storage for the depth value bpp storage for the bpp value This only supports RGB formats here for compat with code that doesn't use pixel formats directly yet. Kernel Hackers Manual July 2017 drm_format_num_planes 9 4.1.27 drm_format_num_planes get the number of planes for format int drm_format_num_planes uint32_t format format pixel format (DRM_FORMAT_*) The number of planes used by the specified pixel format. Kernel Hackers Manual July 2017 drm_format_plane_cpp 9 4.1.27 drm_format_plane_cpp determine the bytes per pixel value int drm_format_plane_cpp uint32_t format int plane format pixel format (DRM_FORMAT_*) plane plane index The bytes per pixel value for the specified plane. Kernel Hackers Manual July 2017 drm_format_horz_chroma_subsampling 9 4.1.27 drm_format_horz_chroma_subsampling get the horizontal chroma subsampling factor int drm_format_horz_chroma_subsampling uint32_t format format pixel format (DRM_FORMAT_*) The horizontal chroma subsampling factor for the specified pixel format. Kernel Hackers Manual July 2017 drm_format_vert_chroma_subsampling 9 4.1.27 drm_format_vert_chroma_subsampling get the vertical chroma subsampling factor int drm_format_vert_chroma_subsampling uint32_t format format pixel format (DRM_FORMAT_*) The vertical chroma subsampling factor for the specified pixel format. Kernel Hackers Manual July 2017 drm_rotation_simplify 9 4.1.27 drm_rotation_simplify Try to simplify the rotation unsigned int drm_rotation_simplify unsigned int rotation unsigned int supported_rotations rotation Rotation to be simplified supported_rotations Supported rotations Attempt to simplify the rotation to a form that is supported. Eg. if the hardware supports everything except DRM_REFLECT_X drm_rotation_simplify(rotation, BIT(DRM_ROTATE_0) | BIT(DRM_ROTATE_90) | BIT(DRM_ROTATE_180) | BIT(DRM_ROTATE_270) | BIT(DRM_REFLECT_Y)); to eliminate the DRM_ROTATE_X flag. Depending on what kind of transforms the hardware supports, this function may not be able to produce a supported transform, so the caller should check the result afterwards. Kernel Hackers Manual July 2017 drm_mode_config_init 9 4.1.27 drm_mode_config_init initialize DRM mode_configuration structure void drm_mode_config_init struct drm_device * dev dev DRM device Initialize dev's mode_config structure, used for tracking the graphics configuration of dev. Since this initializes the modeset locks, no locking is possible. Which is no problem, since this should happen single threaded at init time. It is the driver's problem to ensure this guarantee. Kernel Hackers Manual July 2017 drm_mode_config_cleanup 9 4.1.27 drm_mode_config_cleanup free up DRM mode_config info void drm_mode_config_cleanup struct drm_device * dev dev DRM device Free up all the connectors and CRTCs associated with this DRM device, then free up the framebuffers and associated buffer objects. Note that since this /should/ happen single-threaded at driver/device teardown time, no locking is required. It's the driver's job to ensure that this guarantee actually holds true. cleanup any dangling user buffer objects too Kernel Hackers Manual July 2017 drm_mode_get_tile_group 9 4.1.27 drm_mode_get_tile_group get a reference to an existing tile group struct drm_tile_group * drm_mode_get_tile_group struct drm_device * dev char topology[8] dev DRM device topology[8] 8-bytes unique per monitor. Use the unique bytes to get a reference to an existing tile group. tile group or NULL if not found. Kernel Hackers Manual July 2017 drm_mode_create_tile_group 9 4.1.27 drm_mode_create_tile_group create a tile group from a displayid description struct drm_tile_group * drm_mode_create_tile_group struct drm_device * dev char topology[8] dev DRM device topology[8] 8-bytes unique per monitor. Create a tile group for the unique monitor, and get a unique identifier for the tile group. new tile group or error. Kernel Hackers Manual July 2017 struct drm_crtc_state 9 4.1.27 struct drm_crtc_state mutable CRTC state struct drm_crtc_state { struct drm_crtc * crtc; bool enable; bool active; bool planes_changed:1; bool mode_changed:1; bool active_changed:1; u32 plane_mask; u32 last_vblank_count; struct drm_display_mode adjusted_mode; struct drm_display_mode mode; struct drm_pending_vblank_event * event; struct drm_atomic_state * state; }; crtc backpointer to the CRTC enable whether the CRTC should be enabled, gates all other state active whether the CRTC is actively displaying (used for DPMS) planes_changed for use by helpers and drivers when computing state updates mode_changed for use by helpers and drivers when computing state updates active_changed for use by helpers and drivers when computing state updates plane_mask bitmask of (1 << drm_plane_index(plane)) of attached planes last_vblank_count for helpers and drivers to capture the vblank of the update to ensure framebuffer cleanup isn't done too early adjusted_mode for use by helpers and drivers to compute adjusted mode timings mode current mode timings event optional pointer to a DRM event to signal upon completion of the state update state backpointer to global drm_atomic_state Note that the distinction between enable and active is rather subtile: Flipping active while enable is set without changing anything else may never return in a failure from the ->atomic_check callback. Userspace assumes that a DPMS On will always succeed. In other words: enable controls resource assignment, active controls the actual hardware state. Kernel Hackers Manual July 2017 struct drm_crtc_funcs 9 4.1.27 struct drm_crtc_funcs control CRTCs for a given device struct drm_crtc_funcs { void (* save) (struct drm_crtc *crtc); void (* restore) (struct drm_crtc *crtc); void (* reset) (struct drm_crtc *crtc); int (* cursor_set) (struct drm_crtc *crtc, struct drm_file *file_priv,uint32_t handle, uint32_t width, uint32_t height); int (* cursor_set2) (struct drm_crtc *crtc, struct drm_file *file_priv,uint32_t handle, uint32_t width, uint32_t height,int32_t hot_x, int32_t hot_y); int (* cursor_move) (struct drm_crtc *crtc, int x, int y); void (* gamma_set) (struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b,uint32_t start, uint32_t size); void (* destroy) (struct drm_crtc *crtc); int (* set_config) (struct drm_mode_set *set); int (* page_flip) (struct drm_crtc *crtc,struct drm_framebuffer *fb,struct drm_pending_vblank_event *event,uint32_t flags); int (* set_property) (struct drm_crtc *crtc,struct drm_property *property, uint64_t val); struct drm_crtc_state *(* atomic_duplicate_state) (struct drm_crtc *crtc); void (* atomic_destroy_state) (struct drm_crtc *crtc,struct drm_crtc_state *state); int (* atomic_set_property) (struct drm_crtc *crtc,struct drm_crtc_state *state,struct drm_property *property,uint64_t val); int (* atomic_get_property) (struct drm_crtc *crtc,const struct drm_crtc_state *state,struct drm_property *property,uint64_t *val); }; save save CRTC state restore restore CRTC state reset reset CRTC after state has been invalidated (e.g. resume) cursor_set setup the cursor cursor_set2 setup the cursor with hotspot, superseeds cursor_set if set cursor_move move the cursor gamma_set specify color ramp for CRTC destroy deinit and free object set_config apply a new CRTC configuration page_flip initiate a page flip set_property called when a property is changed atomic_duplicate_state duplicate the atomic state for this CRTC atomic_destroy_state destroy an atomic state for this CRTC atomic_set_property set a property on an atomic state for this CRTC (do not call directly, use drm_atomic_crtc_set_property) atomic_get_property get a property on an atomic state for this CRTC (do not call directly, use drm_atomic_crtc_get_property) The drm_crtc_funcs structure is the central CRTC management structure in the DRM. Each CRTC controls one or more connectors (note that the name CRTC is simply historical, a CRTC may control LVDS, VGA, DVI, TV out, etc. connectors, not just CRTs). Each driver is responsible for filling out this structure at startup time, in addition to providing other modesetting features, like i2c and DDC bus accessors. Kernel Hackers Manual July 2017 struct drm_crtc 9 4.1.27 struct drm_crtc central CRTC control structure struct drm_crtc { struct drm_device * dev; struct device_node * port; struct list_head head; struct drm_modeset_lock mutex; struct drm_mode_object base; struct drm_plane * primary; struct drm_plane * cursor; int cursor_x; int cursor_y; bool enabled; struct drm_display_mode mode; struct drm_display_mode hwmode; bool invert_dimensions; int x; int y; const struct drm_crtc_funcs * funcs; uint32_t gamma_size; uint16_t * gamma_store; int framedur_ns; int linedur_ns; int pixeldur_ns; const void * helper_private; struct drm_object_properties properties; struct drm_crtc_state * state; struct drm_modeset_acquire_ctx * acquire_ctx; }; dev parent DRM device port OF node used by drm_of_find_possible_crtcs head list management mutex per-CRTC locking base base KMS object for ID tracking etc. primary primary plane for this CRTC cursor cursor plane for this CRTC cursor_x current x position of the cursor, used for universal cursor planes cursor_y current y position of the cursor, used for universal cursor planes enabled is this CRTC enabled? mode current mode timings hwmode mode timings as programmed to hw regs invert_dimensions for purposes of error checking crtc vs fb sizes, invert the width/height of the crtc. This is used if the driver is performing 90 or 270 degree rotated scanout x x position on screen y y position on screen funcs CRTC control functions gamma_size size of gamma ramp gamma_store gamma ramp values framedur_ns precise frame timing linedur_ns precise line timing pixeldur_ns precise pixel timing helper_private mid-layer private data properties property tracking for this CRTC state current atomic state for this CRTC acquire_ctx per-CRTC implicit acquire context used by atomic drivers for legacy ioctls Each CRTC may have one or more connectors associated with it. This structure allows the CRTC to be controlled. Kernel Hackers Manual July 2017 struct drm_connector_state 9 4.1.27 struct drm_connector_state mutable connector state struct drm_connector_state { struct drm_connector * connector; struct drm_crtc * crtc; struct drm_encoder * best_encoder; struct drm_atomic_state * state; }; connector backpointer to the connector crtc CRTC to connect connector to, NULL if disabled best_encoder can be used by helpers and drivers to select the encoder state backpointer to global drm_atomic_state Kernel Hackers Manual July 2017 struct drm_connector_funcs 9 4.1.27 struct drm_connector_funcs control connectors on a given device struct drm_connector_funcs { void (* dpms) (struct drm_connector *connector, int mode); void (* save) (struct drm_connector *connector); void (* restore) (struct drm_connector *connector); void (* reset) (struct drm_connector *connector); enum drm_connector_status (* detect) (struct drm_connector *connector,bool force); int (* fill_modes) (struct drm_connector *connector, uint32_t max_width, uint32_t max_height); int (* set_property) (struct drm_connector *connector, struct drm_property *property,uint64_t val); void (* destroy) (struct drm_connector *connector); void (* force) (struct drm_connector *connector); struct drm_connector_state *(* atomic_duplicate_state) (struct drm_connector *connector); void (* atomic_destroy_state) (struct drm_connector *connector,struct drm_connector_state *state); int (* atomic_set_property) (struct drm_connector *connector,struct drm_connector_state *state,struct drm_property *property,uint64_t val); int (* atomic_get_property) (struct drm_connector *connector,const struct drm_connector_state *state,struct drm_property *property,uint64_t *val); }; dpms set power state save save connector state restore restore connector state reset reset connector after state has been invalidated (e.g. resume) detect is this connector active? fill_modes fill mode list for this connector set_property property for this connector may need an update destroy make object go away force notify the driver that the connector is forced on atomic_duplicate_state duplicate the atomic state for this connector atomic_destroy_state destroy an atomic state for this connector atomic_set_property set a property on an atomic state for this connector (do not call directly, use drm_atomic_connector_set_property) atomic_get_property get a property on an atomic state for this connector (do not call directly, use drm_atomic_connector_get_property) Each CRTC may have one or more connectors attached to it. The functions below allow the core DRM code to control connectors, enumerate available modes, etc. Kernel Hackers Manual July 2017 struct drm_encoder_funcs 9 4.1.27 struct drm_encoder_funcs encoder controls struct drm_encoder_funcs { void (* reset) (struct drm_encoder *encoder); void (* destroy) (struct drm_encoder *encoder); }; reset reset state (e.g. at init or resume time) destroy cleanup and free associated data Encoders sit between CRTCs and connectors. Kernel Hackers Manual July 2017 struct drm_encoder 9 4.1.27 struct drm_encoder central DRM encoder structure struct drm_encoder { struct drm_device * dev; struct list_head head; struct drm_mode_object base; char * name; int encoder_type; uint32_t possible_crtcs; uint32_t possible_clones; struct drm_crtc * crtc; struct drm_bridge * bridge; const struct drm_encoder_funcs * funcs; const void * helper_private; }; dev parent DRM device head list management base base KMS object name encoder name encoder_type one of the DRM_MODE_ENCODER_<foo> types in drm_mode.h possible_crtcs bitmask of potential CRTC bindings possible_clones bitmask of potential sibling encoders for cloning crtc currently bound CRTC bridge bridge associated to the encoder funcs control functions helper_private mid-layer private data CRTCs drive pixels to encoders, which convert them into signals appropriate for a given connector or set of connectors. Kernel Hackers Manual July 2017 struct drm_connector 9 4.1.27 struct drm_connector central DRM connector control structure struct drm_connector { struct drm_device * dev; struct device * kdev; struct device_attribute * attr; struct list_head head; struct drm_mode_object base; char * name; int connector_type; int connector_type_id; bool interlace_allowed; bool doublescan_allowed; bool stereo_allowed; struct list_head modes; enum drm_connector_status status; struct list_head probed_modes; struct drm_display_info display_info; const struct drm_connector_funcs * funcs; struct drm_property_blob * edid_blob_ptr; struct drm_object_properties properties; struct drm_property_blob * path_blob_ptr; uint8_t polled; int dpms; const void * helper_private; struct drm_cmdline_mode cmdline_mode; enum drm_connector_force force; bool override_edid; uint32_t encoder_ids[DRM_CONNECTOR_MAX_ENCODER]; struct drm_encoder * encoder; uint8_t eld[MAX_ELD_BYTES]; bool dvi_dual; int max_tmds_clock; bool latency_present[2]; int video_latency[2]; int audio_latency[2]; int null_edid_counter; unsigned bad_edid_counter; struct dentry * debugfs_entry; struct drm_connector_state * state; bool has_tile; struct drm_tile_group * tile_group; bool tile_is_single_monitor; uint8_t num_h_tile; uint8_t num_v_tile; uint8_t tile_h_loc; uint8_t tile_v_loc; uint16_t tile_h_size; uint16_t tile_v_size; }; dev parent DRM device kdev kernel device for sysfs attributes attr sysfs attributes head list management base base KMS object name connector name connector_type one of the DRM_MODE_CONNECTOR_<foo> types from drm_mode.h connector_type_id index into connector type enum interlace_allowed can this connector handle interlaced modes? doublescan_allowed can this connector handle doublescan? stereo_allowed can this connector handle stereo modes? modes modes available on this connector (from fill_modes + user) status one of the drm_connector_status enums (connected, not, or unknown) probed_modes list of modes derived directly from the display display_info information about attached display (e.g. from EDID) funcs connector control functions edid_blob_ptr DRM property containing EDID if present properties property tracking for this connector path_blob_ptr DRM blob property data for the DP MST path property polled a DRM_CONNECTOR_POLL_<foo> value for core driven polling dpms current dpms state helper_private mid-layer private data cmdline_mode mode line parsed from the kernel cmdline for this connector force a DRM_FORCE_<foo> state for forced mode sets override_edid has the EDID been overwritten through debugfs for testing? encoder_ids[DRM_CONNECTOR_MAX_ENCODER] valid encoders for this connector encoder encoder driving this connector, if any eld[MAX_ELD_BYTES] EDID-like data, if present dvi_dual dual link DVI, if found max_tmds_clock max clock rate, if found latency_present[2] AV delay info from ELD, if found video_latency[2] video latency info from ELD, if found audio_latency[2] audio latency info from ELD, if found null_edid_counter track sinks that give us all zeros for the EDID bad_edid_counter track sinks that give us an EDID with invalid checksum debugfs_entry debugfs directory for this connector state current atomic state for this connector has_tile is this connector connected to a tiled monitor tile_group tile group for the connected monitor tile_is_single_monitor whether the tile is one monitor housing num_h_tile number of horizontal tiles in the tile group num_v_tile number of vertical tiles in the tile group tile_h_loc horizontal location of this tile tile_v_loc vertical location of this tile tile_h_size horizontal size of this tile. tile_v_size vertical size of this tile. Each connector may be connected to one or more CRTCs, or may be clonable by another connector if they can share a CRTC. Each connector also has a specific position in the broader display (referred to as a 'screen' though it could span multiple monitors). Kernel Hackers Manual July 2017 struct drm_plane_state 9 4.1.27 struct drm_plane_state mutable plane state struct drm_plane_state { struct drm_plane * plane; struct drm_crtc * crtc; struct drm_framebuffer * fb; struct fence * fence; int32_t crtc_x; int32_t crtc_y; uint32_t crtc_w; uint32_t crtc_h; uint32_t src_x; uint32_t src_y; uint32_t src_h; uint32_t src_w; struct drm_atomic_state * state; }; plane backpointer to the plane crtc currently bound CRTC, NULL if disabled fb currently bound framebuffer fence optional fence to wait for before scanning out fb crtc_x left position of visible portion of plane on crtc crtc_y upper position of visible portion of plane on crtc crtc_w width of visible portion of plane on crtc crtc_h height of visible portion of plane on crtc src_x left position of visible portion of plane within plane (in 16.16) src_y upper position of visible portion of plane within plane (in 16.16) src_h height of visible portion of plane (in 16.16) src_w width of visible portion of plane (in 16.16) state backpointer to global drm_atomic_state Kernel Hackers Manual July 2017 struct drm_plane_funcs 9 4.1.27 struct drm_plane_funcs driver plane control functions struct drm_plane_funcs { int (* update_plane) (struct drm_plane *plane,struct drm_crtc *crtc, struct drm_framebuffer *fb,int crtc_x, int crtc_y,unsigned int crtc_w, unsigned int crtc_h,uint32_t src_x, uint32_t src_y,uint32_t src_w, uint32_t src_h); int (* disable_plane) (struct drm_plane *plane); void (* destroy) (struct drm_plane *plane); void (* reset) (struct drm_plane *plane); int (* set_property) (struct drm_plane *plane,struct drm_property *property, uint64_t val); struct drm_plane_state *(* atomic_duplicate_state) (struct drm_plane *plane); void (* atomic_destroy_state) (struct drm_plane *plane,struct drm_plane_state *state); int (* atomic_set_property) (struct drm_plane *plane,struct drm_plane_state *state,struct drm_property *property,uint64_t val); int (* atomic_get_property) (struct drm_plane *plane,const struct drm_plane_state *state,struct drm_property *property,uint64_t *val); }; update_plane update the plane configuration disable_plane shut down the plane destroy clean up plane resources reset reset plane after state has been invalidated (e.g. resume) set_property called when a property is changed atomic_duplicate_state duplicate the atomic state for this plane atomic_destroy_state destroy an atomic state for this plane atomic_set_property set a property on an atomic state for this plane (do not call directly, use drm_atomic_plane_set_property) atomic_get_property get a property on an atomic state for this plane (do not call directly, use drm_atomic_plane_get_property) Kernel Hackers Manual July 2017 struct drm_plane 9 4.1.27 struct drm_plane central DRM plane control structure struct drm_plane { struct drm_device * dev; struct list_head head; struct drm_mode_object base; uint32_t possible_crtcs; uint32_t * format_types; uint32_t format_count; bool format_default; struct drm_crtc * crtc; struct drm_framebuffer * fb; struct drm_framebuffer * old_fb; const struct drm_plane_funcs * funcs; struct drm_object_properties properties; enum drm_plane_type type; struct drm_plane_state * state; }; dev DRM device this plane belongs to head for list management base base mode object possible_crtcs pipes this plane can be bound to format_types array of formats supported by this plane format_count number of formats supported format_default driver hasn't supplied supported formats for the plane crtc currently bound CRTC fb currently bound fb old_fb Temporary tracking of the old fb while a modeset is ongoing. Used by drm_mode_set_config_internal to implement correct refcounting. funcs helper functions properties property tracking for this plane type type of plane (overlay, primary, cursor) state current atomic state for this plane Kernel Hackers Manual July 2017 struct drm_bridge_funcs 9 4.1.27 struct drm_bridge_funcs drm_bridge control functions struct drm_bridge_funcs { int (* attach) (struct drm_bridge *bridge); bool (* mode_fixup) (struct drm_bridge *bridge,const struct drm_display_mode *mode,struct drm_display_mode *adjusted_mode); void (* disable) (struct drm_bridge *bridge); void (* post_disable) (struct drm_bridge *bridge); void (* mode_set) (struct drm_bridge *bridge,struct drm_display_mode *mode,struct drm_display_mode *adjusted_mode); void (* pre_enable) (struct drm_bridge *bridge); void (* enable) (struct drm_bridge *bridge); }; attach Called during drm_bridge_attach mode_fixup Try to fixup (or reject entirely) proposed mode for this bridge disable Called right before encoder prepare, disables the bridge post_disable Called right after encoder prepare, for lockstepped disable mode_set Set this mode to the bridge pre_enable Called right before encoder commit, for lockstepped commit enable Called right after encoder commit, enables the bridge Kernel Hackers Manual July 2017 struct drm_bridge 9 4.1.27 struct drm_bridge central DRM bridge control structure struct drm_bridge { struct drm_device * dev; #ifdef CONFIG_OF struct device_node * of_node; #endif struct list_head list; const struct drm_bridge_funcs * funcs; void * driver_private; }; dev DRM device this bridge belongs to of_node device node pointer to the bridge list to keep track of all added bridges funcs control functions driver_private pointer to the bridge driver's internal context Kernel Hackers Manual July 2017 struct drm_atomic_state 9 4.1.27 struct drm_atomic_state the global state object for atomic updates struct drm_atomic_state { struct drm_device * dev; bool allow_modeset:1; bool legacy_cursor_update:1; struct drm_plane ** planes; struct drm_plane_state ** plane_states; struct drm_crtc ** crtcs; struct drm_crtc_state ** crtc_states; int num_connector; struct drm_connector ** connectors; struct drm_connector_state ** connector_states; struct drm_modeset_acquire_ctx * acquire_ctx; }; dev parent DRM device allow_modeset allow full modeset legacy_cursor_update hint to enforce legacy cursor ioctl semantics planes pointer to array of plane pointers plane_states pointer to array of plane states pointers crtcs pointer to array of CRTC pointers crtc_states pointer to array of CRTC states pointers num_connector size of the connectors and connector_states arrays connectors pointer to array of connector pointers connector_states pointer to array of connector states pointers acquire_ctx acquire context for this atomic modeset state update Kernel Hackers Manual July 2017 struct drm_mode_set 9 4.1.27 struct drm_mode_set new values for a CRTC config change struct drm_mode_set { struct drm_framebuffer * fb; struct drm_crtc * crtc; struct drm_display_mode * mode; uint32_t x; uint32_t y; struct drm_connector ** connectors; size_t num_connectors; }; fb framebuffer to use for new config crtc CRTC whose configuration we're about to change mode mode timings to use x position of this CRTC relative to fb y position of this CRTC relative to fb connectors array of connectors to drive with this CRTC if possible num_connectors size of connectors array Represents a single crtc the connectors that it drives with what mode and from which framebuffer it scans out from. This is used to set modes. Kernel Hackers Manual July 2017 struct drm_mode_config_funcs 9 4.1.27 struct drm_mode_config_funcs basic driver provided mode setting functions struct drm_mode_config_funcs { struct drm_framebuffer *(* fb_create) (struct drm_device *dev,struct drm_file *file_priv,struct drm_mode_fb_cmd2 *mode_cmd); void (* output_poll_changed) (struct drm_device *dev); int (* atomic_check) (struct drm_device *dev,struct drm_atomic_state *a); int (* atomic_commit) (struct drm_device *dev,struct drm_atomic_state *a,bool async); }; fb_create create a new framebuffer object output_poll_changed function to handle output configuration changes atomic_check check whether a given atomic state update is possible atomic_commit commit an atomic state update previously verified with atomic_check Some global (i.e. not per-CRTC, connector, etc) mode setting functions that involve drivers. Kernel Hackers Manual July 2017 struct drm_mode_group 9 4.1.27 struct drm_mode_group group of mode setting resources for potential sub-grouping struct drm_mode_group { uint32_t num_crtcs; uint32_t num_encoders; uint32_t num_connectors; uint32_t * id_list; }; num_crtcs CRTC count num_encoders encoder count num_connectors connector count id_list list of KMS object IDs in this group Currently this simply tracks the global mode setting state. But in the future it could allow groups of objects to be set aside into independent control groups for use by different user level processes (e.g. two X servers running simultaneously on different heads, each with their own mode configuration and freedom of mode setting). Kernel Hackers Manual July 2017 struct drm_mode_config 9 4.1.27 struct drm_mode_config Mode configuration control structure struct drm_mode_config { struct mutex mutex; struct drm_modeset_lock connection_mutex; struct drm_modeset_acquire_ctx * acquire_ctx; struct mutex idr_mutex; struct idr crtc_idr; struct mutex fb_lock; int num_fb; struct list_head fb_list; int num_connector; struct list_head connector_list; int num_encoder; struct list_head encoder_list; int num_overlay_plane; int num_total_plane; struct list_head plane_list; int num_crtc; struct list_head crtc_list; struct list_head property_list; int min_width; int min_height; int max_width; int max_height; const struct drm_mode_config_funcs * funcs; resource_size_t fb_base; bool poll_enabled; bool poll_running; struct delayed_work output_poll_work; struct list_head property_blob_list; uint32_t preferred_depth; uint32_t prefer_shadow; bool async_page_flip; uint32_t cursor_width; uint32_t cursor_height; }; mutex mutex protecting KMS related lists and structures connection_mutex ww mutex protecting connector state and routing acquire_ctx global implicit acquire context used by atomic drivers for legacy ioctls idr_mutex mutex for KMS ID allocation and management crtc_idr main KMS ID tracking object fb_lock mutex to protect fb state and lists num_fb number of fbs available fb_list list of framebuffers available num_connector number of connectors on this device connector_list list of connector objects num_encoder number of encoders on this device encoder_list list of encoder objects num_overlay_plane number of overlay planes on this device num_total_plane number of universal (i.e. with primary/curso) planes on this device plane_list list of plane objects num_crtc number of CRTCs on this device crtc_list list of CRTC objects property_list list of property objects min_width minimum pixel width on this device min_height minimum pixel height on this device max_width maximum pixel width on this device max_height maximum pixel height on this device funcs core driver provided mode setting functions fb_base base address of the framebuffer poll_enabled track polling support for this device poll_running track polling status for this device output_poll_work delayed work for polling in process context property_blob_list list of all the blob property objects preferred_depth preferred RBG pixel depth, used by fb helpers prefer_shadow hint to userspace to prefer shadow-fb rendering async_page_flip does this device support async flips on the primary plane? cursor_width hint to userspace for max cursor width cursor_height hint to userspace for max cursor height core property tracking Core mode resource tracking structure. All CRTC, encoders, and connectors enumerated by the driver are added here, as are global properties. Some global restrictions are also here, e.g. dimension restrictions. Kernel Hackers Manual July 2017 drm_for_each_plane_mask 9 4.1.27 drm_for_each_plane_mask iterate over planes specified by bitmask drm_for_each_plane_mask plane dev plane_mask plane the loop cursor dev the DRM device plane_mask bitmask of plane indices Iterate over all planes specified by bitmask. Kernel Hackers Manual July 2017 drm_crtc_mask 9 4.1.27 drm_crtc_mask find the mask of a registered CRTC uint32_t drm_crtc_mask struct drm_crtc * crtc crtc CRTC to find mask for Given a registered CRTC, return the mask bit of that CRTC for an encoder's possible_crtcs field. Kernel Hackers Manual July 2017 drm_encoder_crtc_ok 9 4.1.27 drm_encoder_crtc_ok can a given crtc drive a given encoder? bool drm_encoder_crtc_ok struct drm_encoder * encoder struct drm_crtc * crtc encoder encoder to test crtc crtc to test Return false if encoder can't be driven by crtc, true otherwise. As KMS moves toward more fine grained locking, and atomic ioctl where userspace can indirectly control locking order, it becomes necessary to use ww_mutex and acquire-contexts to avoid deadlocks. But because the locking is more distributed around the driver code, we want a bit of extra utility/tracking out of our acquire-ctx. This is provided by drm_modeset_lock / drm_modeset_acquire_ctx. For basic principles of ww_mutex, see: Documentation/locking/ww-mutex-design.txt The basic usage pattern is to: drm_modeset_acquire_init(ctx) retry: foreach (lock in random_ordered_set_of_locks) { ret = drm_modeset_lock(lock, ctx) if (ret == -EDEADLK) { drm_modeset_backoff(ctx); goto retry; } } ... do stuff ... drm_modeset_drop_locks(ctx); drm_modeset_acquire_fini(ctx); Kernel Hackers Manual July 2017 struct drm_modeset_acquire_ctx 9 4.1.27 struct drm_modeset_acquire_ctx locking context (see ww_acquire_ctx) struct drm_modeset_acquire_ctx { struct ww_acquire_ctx ww_ctx; struct drm_modeset_lock * contended; struct list_head locked; bool trylock_only; }; ww_ctx base acquire ctx contended used internally for -EDEADLK handling locked list of held locks trylock_only trylock mode used in atomic contexts/panic notifiers Each thread competing for a set of locks must use one acquire ctx. And if any lock fxn returns -EDEADLK, it must backoff and retry. Kernel Hackers Manual July 2017 drm_modeset_lock_init 9 4.1.27 drm_modeset_lock_init initialize lock void drm_modeset_lock_init struct drm_modeset_lock * lock lock lock to init Kernel Hackers Manual July 2017 drm_modeset_lock_fini 9 4.1.27 drm_modeset_lock_fini cleanup lock void drm_modeset_lock_fini struct drm_modeset_lock * lock lock lock to cleanup Kernel Hackers Manual July 2017 drm_modeset_is_locked 9 4.1.27 drm_modeset_is_locked equivalent to mutex_is_locked bool drm_modeset_is_locked struct drm_modeset_lock * lock lock lock to check Kernel Hackers Manual July 2017 __drm_modeset_lock_all 9 4.1.27 __drm_modeset_lock_all internal helper to grab all modeset locks int __drm_modeset_lock_all struct drm_device * dev bool trylock dev DRM device trylock trylock mode for atomic contexts This is a special version of drm_modeset_lock_all which can also be used in atomic contexts. Then trylock must be set to true. 0 on success or negative error code on failure. Kernel Hackers Manual July 2017 drm_modeset_lock_all 9 4.1.27 drm_modeset_lock_all take all modeset locks void drm_modeset_lock_all struct drm_device * dev dev drm device This function takes all modeset locks, suitable where a more fine-grained scheme isn't (yet) implemented. Locks must be dropped with drm_modeset_unlock_all. Kernel Hackers Manual July 2017 drm_modeset_unlock_all 9 4.1.27 drm_modeset_unlock_all drop all modeset locks void drm_modeset_unlock_all struct drm_device * dev dev device This function drop all modeset locks taken by drm_modeset_lock_all. Kernel Hackers Manual July 2017 drm_modeset_lock_crtc 9 4.1.27 drm_modeset_lock_crtc lock crtc with hidden acquire ctx for a plane update void drm_modeset_lock_crtc struct drm_crtc * crtc struct drm_plane * plane crtc DRM CRTC plane DRM plane to be updated on crtc This function locks the given crtc and plane (which should be either the primary or cursor plane) using a hidden acquire context. This is necessary so that drivers internally using the atomic interfaces can grab further locks with the lock acquire context. Note that plane can be NULL, e.g. when the cursor support hasn't yet been converted to universal planes yet. Kernel Hackers Manual July 2017 drm_modeset_legacy_acquire_ctx 9 4.1.27 drm_modeset_legacy_acquire_ctx find acquire ctx for legacy ioctls struct drm_modeset_acquire_ctx * drm_modeset_legacy_acquire_ctx struct drm_crtc * crtc crtc drm crtc Legacy ioctl operations like cursor updates or page flips only have per-crtc locking, and store the acquire ctx in the corresponding crtc. All other legacy operations take all locks and use a global acquire context. This function grabs the right one. Kernel Hackers Manual July 2017 drm_modeset_unlock_crtc 9 4.1.27 drm_modeset_unlock_crtc drop crtc lock void drm_modeset_unlock_crtc struct drm_crtc * crtc crtc drm crtc This drops the crtc lock acquire with drm_modeset_lock_crtc and all other locks acquired through the hidden context. Kernel Hackers Manual July 2017 drm_warn_on_modeset_not_all_locked 9 4.1.27 drm_warn_on_modeset_not_all_locked check that all modeset locks are locked void drm_warn_on_modeset_not_all_locked struct drm_device * dev dev device Useful as a debug assert. Kernel Hackers Manual July 2017 drm_modeset_acquire_init 9 4.1.27 drm_modeset_acquire_init initialize acquire context void drm_modeset_acquire_init struct drm_modeset_acquire_ctx * ctx uint32_t flags ctx the acquire context flags for future Kernel Hackers Manual July 2017 drm_modeset_acquire_fini 9 4.1.27 drm_modeset_acquire_fini cleanup acquire context void drm_modeset_acquire_fini struct drm_modeset_acquire_ctx * ctx ctx the acquire context Kernel Hackers Manual July 2017 drm_modeset_drop_locks 9 4.1.27 drm_modeset_drop_locks drop all locks void drm_modeset_drop_locks struct drm_modeset_acquire_ctx * ctx ctx the acquire context Drop all locks currently held against this acquire context. Kernel Hackers Manual July 2017 drm_modeset_backoff 9 4.1.27 drm_modeset_backoff deadlock avoidance backoff void drm_modeset_backoff struct drm_modeset_acquire_ctx * ctx ctx the acquire context If deadlock is detected (ie. drm_modeset_lock returns -EDEADLK), you must call this function to drop all currently held locks and block until the contended lock becomes available. Kernel Hackers Manual July 2017 drm_modeset_backoff_interruptible 9 4.1.27 drm_modeset_backoff_interruptible deadlock avoidance backoff int drm_modeset_backoff_interruptible struct drm_modeset_acquire_ctx * ctx ctx the acquire context Interruptible version of drm_modeset_backoff Kernel Hackers Manual July 2017 drm_modeset_lock 9 4.1.27 drm_modeset_lock take modeset lock int drm_modeset_lock struct drm_modeset_lock * lock struct drm_modeset_acquire_ctx * ctx lock lock to take ctx acquire ctx If ctx is not NULL, then its ww acquire context is used and the lock will be tracked by the context and can be released by calling drm_modeset_drop_locks. If -EDEADLK is returned, this means a deadlock scenario has been detected and it is an error to attempt to take any more locks without first calling drm_modeset_backoff. Kernel Hackers Manual July 2017 drm_modeset_lock_interruptible 9 4.1.27 drm_modeset_lock_interruptible take modeset lock int drm_modeset_lock_interruptible struct drm_modeset_lock * lock struct drm_modeset_acquire_ctx * ctx lock lock to take ctx acquire ctx Interruptible version of drm_modeset_lock Kernel Hackers Manual July 2017 drm_modeset_unlock 9 4.1.27 drm_modeset_unlock drop modeset lock void drm_modeset_unlock struct drm_modeset_lock * lock lock lock to release The plane, CRTC, encoder and connector functions provided by the drivers implement the DRM API. They're called by the DRM core and ioctl handlers to handle device state changes and configuration request. As implementing those functions often requires logic not specific to drivers, mid-layer helper functions are available to avoid duplicating boilerplate code. The DRM core contains one mid-layer implementation. The mid-layer provides implementations of several plane, CRTC, encoder and connector functions (called from the top of the mid-layer) that pre-process requests and call lower-level functions provided by the driver (at the bottom of the mid-layer). For instance, the drm_crtc_helper_set_config function can be used to fill the struct drm_crtc_funcs set_config field. When called, it will split the set_config operation in smaller, simpler operations and call the driver to handle them. To use the mid-layer, drivers call drm_crtc_helper_add, drm_encoder_helper_add and drm_connector_helper_add functions to install their mid-layer bottom operations handlers, and fill the drm_crtc_funcs, drm_encoder_funcs and drm_connector_funcs structures with pointers to the mid-layer top API functions. Installing the mid-layer bottom operation handlers is best done right after registering the corresponding KMS object. The mid-layer is not split between CRTC, encoder and connector operations. To use it, a driver must provide bottom functions for all of the three KMS entities. int drm_crtc_helper_set_config(struct drm_mode_set *set); The drm_crtc_helper_set_config helper function is a CRTC set_config implementation. It first tries to locate the best encoder for each connector by calling the connector best_encoder helper operation. After locating the appropriate encoders, the helper function will call the mode_fixup encoder and CRTC helper operations to adjust the requested mode, or reject it completely in which case an error will be returned to the application. If the new configuration after mode adjustment is identical to the current configuration the helper function will return without performing any other operation. If the adjusted mode is identical to the current mode but changes to the frame buffer need to be applied, the drm_crtc_helper_set_config function will call the CRTC mode_set_base helper operation. If the adjusted mode differs from the current mode, or if the mode_set_base helper operation is not provided, the helper function performs a full mode set sequence by calling the prepare, mode_set and commit CRTC and encoder helper operations, in that order. void drm_helper_connector_dpms(struct drm_connector *connector, int mode); The drm_helper_connector_dpms helper function is a connector dpms implementation that tracks power state of connectors. To use the function, drivers must provide dpms helper operations for CRTCs and encoders to apply the DPMS state to the device. The mid-layer doesn't track the power state of CRTCs and encoders. The dpms helper operations can thus be called with a mode identical to the currently active mode. int drm_helper_probe_single_connector_modes(struct drm_connector *connector, uint32_t maxX, uint32_t maxY); The drm_helper_probe_single_connector_modes helper function is a connector fill_modes implementation that updates the connection status for the connector and then retrieves a list of modes by calling the connector get_modes helper operation. If the helper operation returns no mode, and if the connector status is connector_status_connected, standard VESA DMT modes up to 1024x768 are automatically added to the modes list by a call to drm_add_modes_noedid. The function then filters out modes larger than max_width and max_height if specified. It finally calls the optional connector mode_valid helper operation for each mode in the probed list to check whether the mode is valid for the connector. bool (*mode_fixup)(struct drm_crtc *crtc, const struct drm_display_mode *mode, struct drm_display_mode *adjusted_mode); Let CRTCs adjust the requested mode or reject it completely. This operation returns true if the mode is accepted (possibly after being adjusted) or false if it is rejected. The mode_fixup operation should reject the mode if it can't reasonably use it. The definition of "reasonable" is currently fuzzy in this context. One possible behaviour would be to set the adjusted mode to the panel timings when a fixed-mode panel is used with hardware capable of scaling. Another behaviour would be to accept any input mode and adjust it to the closest mode supported by the hardware (FIXME: This needs to be clarified). int (*mode_set_base)(struct drm_crtc *crtc, int x, int y, struct drm_framebuffer *old_fb) Move the CRTC on the current frame buffer (stored in crtc->fb) to position (x,y). Any of the frame buffer, x position or y position may have been modified. This helper operation is optional. If not provided, the drm_crtc_helper_set_config function will fall back to the mode_set helper operation. FIXME: Why are x and y passed as arguments, as they can be accessed through crtc->x and crtc->y? void (*prepare)(struct drm_crtc *crtc); Prepare the CRTC for mode setting. This operation is called after validating the requested mode. Drivers use it to perform device-specific operations required before setting the new mode. int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode, struct drm_display_mode *adjusted_mode, int x, int y, struct drm_framebuffer *old_fb); Set a new mode, position and frame buffer. Depending on the device requirements, the mode can be stored internally by the driver and applied in the commit operation, or programmed to the hardware immediately. The mode_set operation returns 0 on success or a negative error code if an error occurs. void (*commit)(struct drm_crtc *crtc); Commit a mode. This operation is called after setting the new mode. Upon return the device must use the new mode and be fully operational. bool (*mode_fixup)(struct drm_encoder *encoder, const struct drm_display_mode *mode, struct drm_display_mode *adjusted_mode); Let encoders adjust the requested mode or reject it completely. This operation returns true if the mode is accepted (possibly after being adjusted) or false if it is rejected. See the mode_fixup CRTC helper operation for an explanation of the allowed adjustments. void (*prepare)(struct drm_encoder *encoder); Prepare the encoder for mode setting. This operation is called after validating the requested mode. Drivers use it to perform device-specific operations required before setting the new mode. void (*mode_set)(struct drm_encoder *encoder, struct drm_display_mode *mode, struct drm_display_mode *adjusted_mode); Set a new mode. Depending on the device requirements, the mode can be stored internally by the driver and applied in the commit operation, or programmed to the hardware immediately. void (*commit)(struct drm_encoder *encoder); Commit a mode. This operation is called after setting the new mode. Upon return the device must use the new mode and be fully operational. struct drm_encoder *(*best_encoder)(struct drm_connector *connector); Return a pointer to the best encoder for the connecter. Device that map connectors to encoders 1:1 simply return the pointer to the associated encoder. This operation is mandatory. int (*get_modes)(struct drm_connector *connector); Fill the connector's probed_modes list by parsing EDID data with drm_add_edid_modes, adding standard VESA DMT modes with drm_add_modes_noedid, or calling drm_mode_probed_add directly for every supported mode and return the number of modes it has detected. This operation is mandatory. Note that the caller function will automatically add standard VESA DMT modes up to 1024x768 if the get_modes helper operation returns no mode and if the connector status is connector_status_connected. There is no need to call drm_add_edid_modes manually in that case. When adding modes manually the driver creates each mode with a call to drm_mode_create and must fill the following fields. __u32 type; Mode type bitmask, a combination of DRM_MODE_TYPE_BUILTIN not used? DRM_MODE_TYPE_CLOCK_C not used? DRM_MODE_TYPE_CRTC_C not used? DRM_MODE_TYPE_PREFERRED - The preferred mode for the connector not used? DRM_MODE_TYPE_DEFAULT not used? DRM_MODE_TYPE_USERDEF not used? DRM_MODE_TYPE_DRIVER The mode has been created by the driver (as opposed to to user-created modes). Drivers must set the DRM_MODE_TYPE_DRIVER bit for all modes they create, and set the DRM_MODE_TYPE_PREFERRED bit for the preferred mode. __u32 clock; Pixel clock frequency in kHz unit __u16 hdisplay, hsync_start, hsync_end, htotal; __u16 vdisplay, vsync_start, vsync_end, vtotal; Horizontal and vertical timing information <----------------><-------------><--------------> //////////////////////| ////////////////////// | ////////////////////// |.................. ................ _______________ <----- [hv]display -----> <------------- [hv]sync_start ------------> <--------------------- [hv]sync_end ---------------------> <-------------------------------- [hv]total -----------------------------> ]]> __u16 hskew; __u16 vscan; Unknown __u32 flags; Mode flags, a combination of DRM_MODE_FLAG_PHSYNC Horizontal sync is active high DRM_MODE_FLAG_NHSYNC Horizontal sync is active low DRM_MODE_FLAG_PVSYNC Vertical sync is active high DRM_MODE_FLAG_NVSYNC Vertical sync is active low DRM_MODE_FLAG_INTERLACE Mode is interlaced DRM_MODE_FLAG_DBLSCAN Mode uses doublescan DRM_MODE_FLAG_CSYNC Mode uses composite sync DRM_MODE_FLAG_PCSYNC Composite sync is active high DRM_MODE_FLAG_NCSYNC Composite sync is active low DRM_MODE_FLAG_HSKEW hskew provided (not used?) DRM_MODE_FLAG_BCAST not used? DRM_MODE_FLAG_PIXMUX not used? DRM_MODE_FLAG_DBLCLK not used? DRM_MODE_FLAG_CLKDIV2 ? Note that modes marked with the INTERLACE or DBLSCAN flags will be filtered out by drm_helper_probe_single_connector_modes if the connector's interlace_allowed or doublescan_allowed field is set to 0. char name[DRM_DISPLAY_MODE_LEN]; Mode name. The driver must call drm_mode_set_name to fill the mode name from hdisplay, vdisplay and interlace flag after filling the corresponding fields. The vrefresh value is computed by drm_helper_probe_single_connector_modes. When parsing EDID data, drm_add_edid_modes fills the connector display_info width_mm and height_mm fields. When creating modes manually the get_modes helper operation must set the display_info width_mm and height_mm fields if they haven't been set already (for instance at initialization time when a fixed-size panel is attached to the connector). The mode width_mm and height_mm fields are only used internally during EDID parsing and should not be set when creating modes manually. int (*mode_valid)(struct drm_connector *connector, struct drm_display_mode *mode); Verify whether a mode is valid for the connector. Return MODE_OK for supported modes and one of the enum drm_mode_status values (MODE_*) for unsupported modes. This operation is optional. As the mode rejection reason is currently not used beside for immediately removing the unsupported mode, an implementation can return MODE_BAD regardless of the exact reason why the mode is not valid. Note that the mode_valid helper operation is only called for modes detected by the device, and not for modes set by the user through the CRTC set_config operation. This helper library provides implementations of check and commit functions on top of the CRTC modeset helper callbacks and the plane helper callbacks. It also provides convenience implementations for the atomic state handling callbacks for drivers which don't need to subclass the drm core structures to add their own additional internal state. This library also provides default implementations for the check callback in drm_atomic_helper_check and for the commit callback with drm_atomic_helper_commit. But the individual stages and callbacks are expose to allow drivers to mix and match and e.g. use the plane helpers only together with a driver private modeset implementation. This library also provides implementations for all the legacy driver interfaces on top of the atomic interface. See drm_atomic_helper_set_config, drm_atomic_helper_disable_plane, drm_atomic_helper_disable_plane and the various functions to implement set_property callbacks. New drivers must not implement these functions themselves but must use the provided helpers. For now the atomic helpers don't support async commit directly. If there is real need it could be added though, using the dma-buf fence infrastructure for generic synchronization with outstanding rendering. For now drivers have to implement async commit themselves, with the following sequence being the recommended one: 1. Run drm_atomic_helper_prepare_planes first. This is the only function which commit needs to call which can fail, so we want to run it first and synchronously. 2. Synchronize with any outstanding asynchronous commit worker threads which might be affected the new state update. This can be done by either cancelling or flushing the work items, depending upon whether the driver can deal with cancelled updates. Note that it is important to ensure that the framebuffer cleanup is still done when cancelling. For sufficient parallelism it is recommended to have a work item per crtc (for updates which don't touch global state) and a global one. Then we only need to synchronize with the crtc work items for changed crtcs and the global work item, which allows nice concurrent updates on disjoint sets of crtcs. 3. The software state is updated synchronously with drm_atomic_helper_swap_state. Doing this under the protection of all modeset locks means concurrent callers never see inconsistent state. And doing this while it's guaranteed that no relevant async worker runs means that async workers do not need grab any locks. Actually they must not grab locks, for otherwise the work flushing will deadlock. 4. Schedule a work item to do all subsequent steps, using the split-out commit helpers: a) pre-plane commit b) plane commit c) post-plane commit and then cleaning up the framebuffers after the old framebuffer is no longer being displayed. Both the drm core and the atomic helpers assume that there is always the full and correct atomic software state for all connectors, CRTCs and planes available. Which is a bit a problem on driver load and also after system suspend. One way to solve this is to have a hardware state read-out infrastructure which reconstructs the full software state (e.g. the i915 driver). The simpler solution is to just reset the software state to everything off, which is easiest to do by calling drm_mode_config_reset. To facilitate this the atomic helpers provide default reset implementations for all hooks. Kernel Hackers Manual July 2017 drm_atomic_crtc_for_each_plane 9 4.1.27 drm_atomic_crtc_for_each_plane iterate over planes currently attached to CRTC drm_atomic_crtc_for_each_plane plane crtc plane the loop cursor crtc the crtc whose planes are iterated This iterates over the current state, useful (for example) when applying atomic state after it has been checked and swapped. To iterate over the planes which *will* be attached (for ->atomic_check) see drm_crtc_for_each_pending_plane Kernel Hackers Manual July 2017 drm_atomic_crtc_state_for_each_plane 9 4.1.27 drm_atomic_crtc_state_for_each_plane iterate over attached planes in new state drm_atomic_crtc_state_for_each_plane plane crtc_state plane the loop cursor crtc_state the incoming crtc-state Similar to drm_crtc_for_each_plane, but iterates the planes that will be attached if the specified state is applied. Useful during (for example) ->atomic_check operations, to validate the incoming state Kernel Hackers Manual July 2017 drm_atomic_helper_check_modeset 9 4.1.27 drm_atomic_helper_check_modeset validate state object for modeset changes int drm_atomic_helper_check_modeset struct drm_device * dev struct drm_atomic_state * state dev DRM device state the driver state object Check the state object to see if the requested state is physically possible. This does all the crtc and connector related computations for an atomic update. It computes and updates crtc_state->mode_changed, adds any additional connectors needed for full modesets and calls down into ->mode_fixup functions of the driver backend. Drivers which update ->mode_changed (e.g. in their ->atomic_check hooks if a plane update can't be done without a full modeset) _must_ call this function afterwards after that change. It is permitted to call this function multiple times for the same update, e.g. when the ->atomic_check functions depend upon the adjusted dotclock for fifo space allocation and watermark computation. RETURNS Zero for success or -errno Kernel Hackers Manual July 2017 drm_atomic_helper_check_planes 9 4.1.27 drm_atomic_helper_check_planes validate state object for planes changes int drm_atomic_helper_check_planes struct drm_device * dev struct drm_atomic_state * state dev DRM device state the driver state object Check the state object to see if the requested state is physically possible. This does all the plane update related checks using by calling into the ->atomic_check hooks provided by the driver. RETURNS Zero for success or -errno Kernel Hackers Manual July 2017 drm_atomic_helper_check 9 4.1.27 drm_atomic_helper_check validate state object int drm_atomic_helper_check struct drm_device * dev struct drm_atomic_state * state dev DRM device state the driver state object Check the state object to see if the requested state is physically possible. Only crtcs and planes have check callbacks, so for any additional (global) checking that a driver needs it can simply wrap that around this function. Drivers without such needs can directly use this as their ->atomic_check callback. This just wraps the two parts of the state checking for planes and modeset First it calls drm_atomic_helper_check_modeset and then drm_atomic_helper_check_planes. The assumption is that the ->atomic_check functions depend upon an updated adjusted_mode.clock to e.g. properly compute watermarks. RETURNS Zero for success or -errno Kernel Hackers Manual July 2017 drm_atomic_helper_commit_modeset_disables 9 4.1.27 drm_atomic_helper_commit_modeset_disables modeset commit to disable outputs void drm_atomic_helper_commit_modeset_disables struct drm_device * dev struct drm_atomic_state * old_state dev DRM device old_state atomic state object with old state structures This function shuts down all the outputs that need to be shut down and prepares them (if required) with the new mode. For compatability with legacy crtc helpers this should be called before drm_atomic_helper_commit_planes, which is what the default commit function does. But drivers with different needs can group the modeset commits together and do the plane commits at the end. This is useful for drivers doing runtime PM since planes updates then only happen when the CRTC is actually enabled. Kernel Hackers Manual July 2017 drm_atomic_helper_commit_modeset_enables 9 4.1.27 drm_atomic_helper_commit_modeset_enables modeset commit to enable outputs void drm_atomic_helper_commit_modeset_enables struct drm_device * dev struct drm_atomic_state * old_state dev DRM device old_state atomic state object with old state structures This function enables all the outputs with the new configuration which had to be turned off for the update. For compatability with legacy crtc helpers this should be called after drm_atomic_helper_commit_planes, which is what the default commit function does. But drivers with different needs can group the modeset commits together and do the plane commits at the end. This is useful for drivers doing runtime PM since planes updates then only happen when the CRTC is actually enabled. Kernel Hackers Manual July 2017 drm_atomic_helper_wait_for_vblanks 9 4.1.27 drm_atomic_helper_wait_for_vblanks wait for vblank on crtcs void drm_atomic_helper_wait_for_vblanks struct drm_device * dev struct drm_atomic_state * old_state dev DRM device old_state atomic state object with old state structures Helper to, after atomic commit, wait for vblanks on all effected crtcs (ie. before cleaning up old framebuffers using drm_atomic_helper_cleanup_planes). It will only wait on crtcs where the framebuffers have actually changed to optimize for the legacy cursor and plane update use-case. Kernel Hackers Manual July 2017 drm_atomic_helper_commit 9 4.1.27 drm_atomic_helper_commit commit validated state object int drm_atomic_helper_commit struct drm_device * dev struct drm_atomic_state * state bool async dev DRM device state the driver state object async asynchronous commit This function commits a with drm_atomic_helper_check pre-validated state object. This can still fail when e.g. the framebuffer reservation fails. For now this doesn't implement asynchronous commits. RETURNS Zero for success or -errno. Kernel Hackers Manual July 2017 drm_atomic_helper_prepare_planes 9 4.1.27 drm_atomic_helper_prepare_planes prepare plane resources before commit int drm_atomic_helper_prepare_planes struct drm_device * dev struct drm_atomic_state * state dev DRM device state atomic state object with new state structures This function prepares plane state, specifically framebuffers, for the new configuration. If any failure is encountered this function will call ->cleanup_fb on any already successfully prepared framebuffer. 0 on success, negative error code on failure. Kernel Hackers Manual July 2017 drm_atomic_helper_commit_planes 9 4.1.27 drm_atomic_helper_commit_planes commit plane state void drm_atomic_helper_commit_planes struct drm_device * dev struct drm_atomic_state * old_state dev DRM device old_state atomic state object with old state structures This function commits the new plane state using the plane and atomic helper functions for planes and crtcs. It assumes that the atomic state has already been pushed into the relevant object state pointers, since this step can no longer fail. It still requires the global state object old_state to know which planes and crtcs need to be updated though. Kernel Hackers Manual July 2017 drm_atomic_helper_cleanup_planes 9 4.1.27 drm_atomic_helper_cleanup_planes cleanup plane resources after commit void drm_atomic_helper_cleanup_planes struct drm_device * dev struct drm_atomic_state * old_state dev DRM device old_state atomic state object with old state structures This function cleans up plane state, specifically framebuffers, from the old configuration. Hence the old configuration must be perserved in old_state to be able to call this function. This function must also be called on the new state when the atomic update fails at any point after calling drm_atomic_helper_prepare_planes. Kernel Hackers Manual July 2017 drm_atomic_helper_swap_state 9 4.1.27 drm_atomic_helper_swap_state store atomic state into current sw state void drm_atomic_helper_swap_state struct drm_device * dev struct drm_atomic_state * state dev DRM device state atomic state This function stores the atomic state into the current state pointers in all driver objects. It should be called after all failing steps have been done and succeeded, but before the actual hardware state is committed. For cleanup and error recovery the current state for all changed objects will be swaped into state. With that sequence it fits perfectly into the plane prepare/cleanup sequence: 1. Call drm_atomic_helper_prepare_planes with the staged atomic state. 2. Do any other steps that might fail. 3. Put the staged state into the current state pointers with this function. 4. Actually commit the hardware state. 5. Call drm_atomic_helper_cleanup_planes with state, which since step 3 contains the old state. Also do any other cleanup required with that state. Kernel Hackers Manual July 2017 drm_atomic_helper_update_plane 9 4.1.27 drm_atomic_helper_update_plane Helper for primary plane update using atomic int drm_atomic_helper_update_plane struct drm_plane * plane struct drm_crtc * crtc struct drm_framebuffer * fb int crtc_x int crtc_y unsigned int crtc_w unsigned int crtc_h uint32_t src_x uint32_t src_y uint32_t src_w uint32_t src_h plane plane object to update crtc owning CRTC of owning plane fb framebuffer to flip onto plane crtc_x x offset of primary plane on crtc crtc_y y offset of primary plane on crtc crtc_w width of primary plane rectangle on crtc crtc_h height of primary plane rectangle on crtc src_x x offset of fb for panning src_y y offset of fb for panning src_w width of source rectangle in fb src_h height of source rectangle in fb Provides a default plane update handler using the atomic driver interface. Zero on success, error code on failure Kernel Hackers Manual July 2017 drm_atomic_helper_disable_plane 9 4.1.27 drm_atomic_helper_disable_plane Helper for primary plane disable using * atomic int drm_atomic_helper_disable_plane struct drm_plane * plane plane plane to disable Provides a default plane disable handler using the atomic driver interface. Zero on success, error code on failure Kernel Hackers Manual July 2017 drm_atomic_helper_set_config 9 4.1.27 drm_atomic_helper_set_config set a new config from userspace int drm_atomic_helper_set_config struct drm_mode_set * set set mode set configuration Provides a default crtc set_config handler using the atomic driver interface. Returns 0 on success, negative errno numbers on failure. Kernel Hackers Manual July 2017 drm_atomic_helper_crtc_set_property 9 4.1.27 drm_atomic_helper_crtc_set_property helper for crtc properties int drm_atomic_helper_crtc_set_property struct drm_crtc * crtc struct drm_property * property uint64_t val crtc DRM crtc property DRM property val value of property Provides a default crtc set_property handler using the atomic driver interface. Zero on success, error code on failure Kernel Hackers Manual July 2017 drm_atomic_helper_plane_set_property 9 4.1.27 drm_atomic_helper_plane_set_property helper for plane properties int drm_atomic_helper_plane_set_property struct drm_plane * plane struct drm_property * property uint64_t val plane DRM plane property DRM property val value of property Provides a default plane set_property handler using the atomic driver interface. Zero on success, error code on failure Kernel Hackers Manual July 2017 drm_atomic_helper_connector_set_property 9 4.1.27 drm_atomic_helper_connector_set_property helper for connector properties int drm_atomic_helper_connector_set_property struct drm_connector * connector struct drm_property * property uint64_t val connector DRM connector property DRM property val value of property Provides a default connector set_property handler using the atomic driver interface. Zero on success, error code on failure Kernel Hackers Manual July 2017 drm_atomic_helper_page_flip 9 4.1.27 drm_atomic_helper_page_flip execute a legacy page flip int drm_atomic_helper_page_flip struct drm_crtc * crtc struct drm_framebuffer * fb struct drm_pending_vblank_event * event uint32_t flags crtc DRM crtc fb DRM framebuffer event optional DRM event to signal upon completion flags flip flags for non-vblank sync'ed updates Provides a default page flip implementation using the atomic driver interface. Note that for now so called async page flips (i.e. updates which are not synchronized to vblank) are not supported, since the atomic interfaces have no provisions for this yet. Returns 0 on success, negative errno numbers on failure. Kernel Hackers Manual July 2017 drm_atomic_helper_connector_dpms 9 4.1.27 drm_atomic_helper_connector_dpms connector dpms helper implementation void drm_atomic_helper_connector_dpms struct drm_connector * connector int mode connector affected connector mode DPMS mode This is the main helper function provided by the atomic helper framework for implementing the legacy DPMS connector interface. It computes the new desired ->active state for the corresponding CRTC (if the connector is enabled) and updates it. Kernel Hackers Manual July 2017 drm_atomic_helper_crtc_reset 9 4.1.27 drm_atomic_helper_crtc_reset default ->reset hook for CRTCs void drm_atomic_helper_crtc_reset struct drm_crtc * crtc crtc drm CRTC Resets the atomic state for crtc by freeing the state pointer (which might be NULL, e.g. at driver load time) and allocating a new empty state object. Kernel Hackers Manual July 2017 __drm_atomic_helper_crtc_duplicate_state 9 4.1.27 __drm_atomic_helper_crtc_duplicate_state copy atomic CRTC state void __drm_atomic_helper_crtc_duplicate_state struct drm_crtc * crtc struct drm_crtc_state * state crtc CRTC object state atomic CRTC state Copies atomic state from a CRTC's current state and resets inferred values. This is useful for drivers that subclass the CRTC state. Kernel Hackers Manual July 2017 drm_atomic_helper_crtc_duplicate_state 9 4.1.27 drm_atomic_helper_crtc_duplicate_state default state duplicate hook struct drm_crtc_state * drm_atomic_helper_crtc_duplicate_state struct drm_crtc * crtc crtc drm CRTC Default CRTC state duplicate hook for drivers which don't have their own subclassed CRTC state structure. Kernel Hackers Manual July 2017 __drm_atomic_helper_crtc_destroy_state 9 4.1.27 __drm_atomic_helper_crtc_destroy_state release CRTC state void __drm_atomic_helper_crtc_destroy_state struct drm_crtc * crtc struct drm_crtc_state * state crtc CRTC object state CRTC state object to release Releases all resources stored in the CRTC state without actually freeing the memory of the CRTC state. This is useful for drivers that subclass the CRTC state. Kernel Hackers Manual July 2017 drm_atomic_helper_crtc_destroy_state 9 4.1.27 drm_atomic_helper_crtc_destroy_state default state destroy hook void drm_atomic_helper_crtc_destroy_state struct drm_crtc * crtc struct drm_crtc_state * state crtc drm CRTC state CRTC state object to release Default CRTC state destroy hook for drivers which don't have their own subclassed CRTC state structure. Kernel Hackers Manual July 2017 drm_atomic_helper_plane_reset 9 4.1.27 drm_atomic_helper_plane_reset default ->reset hook for planes void drm_atomic_helper_plane_reset struct drm_plane * plane plane drm plane Resets the atomic state for plane by freeing the state pointer (which might be NULL, e.g. at driver load time) and allocating a new empty state object. Kernel Hackers Manual July 2017 __drm_atomic_helper_plane_duplicate_state 9 4.1.27 __drm_atomic_helper_plane_duplicate_state copy atomic plane state void __drm_atomic_helper_plane_duplicate_state struct drm_plane * plane struct drm_plane_state * state plane plane object state atomic plane state Copies atomic state from a plane's current state. This is useful for drivers that subclass the plane state. Kernel Hackers Manual July 2017 drm_atomic_helper_plane_duplicate_state 9 4.1.27 drm_atomic_helper_plane_duplicate_state default state duplicate hook struct drm_plane_state * drm_atomic_helper_plane_duplicate_state struct drm_plane * plane plane drm plane Default plane state duplicate hook for drivers which don't have their own subclassed plane state structure. Kernel Hackers Manual July 2017 __drm_atomic_helper_plane_destroy_state 9 4.1.27 __drm_atomic_helper_plane_destroy_state release plane state void __drm_atomic_helper_plane_destroy_state struct drm_plane * plane struct drm_plane_state * state plane plane object state plane state object to release Releases all resources stored in the plane state without actually freeing the memory of the plane state. This is useful for drivers that subclass the plane state. Kernel Hackers Manual July 2017 drm_atomic_helper_plane_destroy_state 9 4.1.27 drm_atomic_helper_plane_destroy_state default state destroy hook void drm_atomic_helper_plane_destroy_state struct drm_plane * plane struct drm_plane_state * state plane drm plane state plane state object to release Default plane state destroy hook for drivers which don't have their own subclassed plane state structure. Kernel Hackers Manual July 2017 drm_atomic_helper_connector_reset 9 4.1.27 drm_atomic_helper_connector_reset default ->reset hook for connectors void drm_atomic_helper_connector_reset struct drm_connector * connector connector drm connector Resets the atomic state for connector by freeing the state pointer (which might be NULL, e.g. at driver load time) and allocating a new empty state object. Kernel Hackers Manual July 2017 __drm_atomic_helper_connector_duplicate_state 9 4.1.27 __drm_atomic_helper_connector_duplicate_state copy atomic connector state void __drm_atomic_helper_connector_duplicate_state struct drm_connector * connector struct drm_connector_state * state connector connector object state atomic connector state Copies atomic state from a connector's current state. This is useful for drivers that subclass the connector state. Kernel Hackers Manual July 2017 drm_atomic_helper_connector_duplicate_state 9 4.1.27 drm_atomic_helper_connector_duplicate_state default state duplicate hook struct drm_connector_state * drm_atomic_helper_connector_duplicate_state struct drm_connector * connector connector drm connector Default connector state duplicate hook for drivers which don't have their own subclassed connector state structure. Kernel Hackers Manual July 2017 __drm_atomic_helper_connector_destroy_state 9 4.1.27 __drm_atomic_helper_connector_destroy_state release connector state void __drm_atomic_helper_connector_destroy_state struct drm_connector * connector struct drm_connector_state * state connector connector object state connector state object to release Releases all resources stored in the connector state without actually freeing the memory of the connector state. This is useful for drivers that subclass the connector state. Kernel Hackers Manual July 2017 drm_atomic_helper_connector_destroy_state 9 4.1.27 drm_atomic_helper_connector_destroy_state default state destroy hook void drm_atomic_helper_connector_destroy_state struct drm_connector * connector struct drm_connector_state * state connector drm connector state connector state object to release Default connector state destroy hook for drivers which don't have their own subclassed connector state structure. Kernel Hackers Manual July 2017 struct drm_crtc_helper_funcs 9 4.1.27 struct drm_crtc_helper_funcs helper operations for CRTCs struct drm_crtc_helper_funcs { void (* dpms) (struct drm_crtc *crtc, int mode); void (* prepare) (struct drm_crtc *crtc); void (* commit) (struct drm_crtc *crtc); bool (* mode_fixup) (struct drm_crtc *crtc,const struct drm_display_mode *mode,struct drm_display_mode *adjusted_mode); int (* mode_set) (struct drm_crtc *crtc, struct drm_display_mode *mode,struct drm_display_mode *adjusted_mode, int x, int y,struct drm_framebuffer *old_fb); void (* mode_set_nofb) (struct drm_crtc *crtc); int (* mode_set_base) (struct drm_crtc *crtc, int x, int y,struct drm_framebuffer *old_fb); int (* mode_set_base_atomic) (struct drm_crtc *crtc,struct drm_framebuffer *fb, int x, int y,enum mode_set_atomic); void (* load_lut) (struct drm_crtc *crtc); void (* disable) (struct drm_crtc *crtc); void (* enable) (struct drm_crtc *crtc); int (* atomic_check) (struct drm_crtc *crtc,struct drm_crtc_state *state); void (* atomic_begin) (struct drm_crtc *crtc); void (* atomic_flush) (struct drm_crtc *crtc); }; dpms set power state prepare prepare the CRTC, called before mode_set commit commit changes to CRTC, called after mode_set mode_fixup try to fixup proposed mode for this CRTC mode_set set this mode mode_set_nofb set mode only (no scanout buffer attached) mode_set_base update the scanout buffer mode_set_base_atomic non-blocking mode set (used for kgdb support) load_lut load color palette disable disable CRTC when no longer in use enable enable CRTC atomic_check check for validity of an atomic state atomic_begin begin atomic update atomic_flush flush atomic update The helper operations are called by the mid-layer CRTC helper. Note that with atomic helpers dpms, prepare and commit hooks are deprecated. Used enable and disable instead exclusively. With legacy crtc helpers there's a big semantic difference between disable disable also needs to release any resources acquired in mode_set (like shared PLLs). Kernel Hackers Manual July 2017 struct drm_encoder_helper_funcs 9 4.1.27 struct drm_encoder_helper_funcs helper operations for encoders struct drm_encoder_helper_funcs { void (* dpms) (struct drm_encoder *encoder, int mode); void (* save) (struct drm_encoder *encoder); void (* restore) (struct drm_encoder *encoder); bool (* mode_fixup) (struct drm_encoder *encoder,const struct drm_display_mode *mode,struct drm_display_mode *adjusted_mode); void (* prepare) (struct drm_encoder *encoder); void (* commit) (struct drm_encoder *encoder); void (* mode_set) (struct drm_encoder *encoder,struct drm_display_mode *mode,struct drm_display_mode *adjusted_mode); struct drm_crtc *(* get_crtc) (struct drm_encoder *encoder); enum drm_connector_status (* detect) (struct drm_encoder *encoder,struct drm_connector *connector); void (* disable) (struct drm_encoder *encoder); void (* enable) (struct drm_encoder *encoder); int (* atomic_check) (struct drm_encoder *encoder,struct drm_crtc_state *crtc_state,struct drm_connector_state *conn_state); }; dpms set power state save save connector state restore restore connector state mode_fixup try to fixup proposed mode for this connector prepare part of the disable sequence, called before the CRTC modeset commit called after the CRTC modeset mode_set set this mode, optional for atomic helpers get_crtc return CRTC that the encoder is currently attached to detect connection status detection disable disable encoder when not in use (overrides DPMS off) enable enable encoder atomic_check check for validity of an atomic update The helper operations are called by the mid-layer CRTC helper. Note that with atomic helpers dpms, prepare and commit hooks are deprecated. Used enable and disable instead exclusively. With legacy crtc helpers there's a big semantic difference between disable disable also needs to release any resources acquired in mode_set (like shared PLLs). Kernel Hackers Manual July 2017 struct drm_connector_helper_funcs 9 4.1.27 struct drm_connector_helper_funcs helper operations for connectors struct drm_connector_helper_funcs { int (* get_modes) (struct drm_connector *connector); enum drm_mode_status (* mode_valid) (struct drm_connector *connector,struct drm_display_mode *mode); struct drm_encoder *(* best_encoder) (struct drm_connector *connector); }; get_modes get mode list for this connector mode_valid is this mode valid on the given connector? (optional) best_encoder return the preferred encoder for this connector The helper operations are called by the mid-layer CRTC helper. Kernel Hackers Manual July 2017 drm_helper_move_panel_connectors_to_head 9 4.1.27 drm_helper_move_panel_connectors_to_head move panels to the front in the connector list void drm_helper_move_panel_connectors_to_head struct drm_device * dev dev drm device to operate on Some userspace presumes that the first connected connector is the main display, where it's supposed to display e.g. the login screen. For laptops, this should be the main panel. Use this function to sort all (eDP/LVDS) panels to the front of the connector list, instead of painstakingly trying to initialize them in the right order. Kernel Hackers Manual July 2017 drm_helper_encoder_in_use 9 4.1.27 drm_helper_encoder_in_use check if a given encoder is in use bool drm_helper_encoder_in_use struct drm_encoder * encoder encoder encoder to check Checks whether encoder is with the current mode setting output configuration in use by any connector. This doesn't mean that it is actually enabled since the DPMS state is tracked separately. True if encoder is used, false otherwise. Kernel Hackers Manual July 2017 drm_helper_crtc_in_use 9 4.1.27 drm_helper_crtc_in_use check if a given CRTC is in a mode_config bool drm_helper_crtc_in_use struct drm_crtc * crtc crtc CRTC to check Checks whether crtc is with the current mode setting output configuration in use by any connector. This doesn't mean that it is actually enabled since the DPMS state is tracked separately. True if crtc is used, false otherwise. Kernel Hackers Manual July 2017 drm_helper_disable_unused_functions 9 4.1.27 drm_helper_disable_unused_functions disable unused objects void drm_helper_disable_unused_functions struct drm_device * dev dev DRM device This function walks through the entire mode setting configuration of dev. It will remove any crtc links of unused encoders and encoder links of disconnected connectors. Then it will disable all unused encoders and crtcs either by calling their disable callback if available or by calling their dpms callback with DRM_MODE_DPMS_OFF. Kernel Hackers Manual July 2017 drm_crtc_helper_set_mode 9 4.1.27 drm_crtc_helper_set_mode internal helper to set a mode bool drm_crtc_helper_set_mode struct drm_crtc * crtc struct drm_display_mode * mode int x int y struct drm_framebuffer * old_fb crtc CRTC to program mode mode to use x horizontal offset into the surface y vertical offset into the surface old_fb old framebuffer, for cleanup Try to set mode on crtc. Give crtc and its associated connectors a chance to fixup or reject the mode prior to trying to set it. This is an internal helper that drivers could e.g. use to update properties that require the entire output pipe to be disabled and re-enabled in a new configuration. For example for changing whether audio is enabled on a hdmi link or for changing panel fitter or dither attributes. It is also called by the drm_crtc_helper_set_config helper function to drive the mode setting sequence. True if the mode was set successfully, false otherwise. Kernel Hackers Manual July 2017 drm_crtc_helper_set_config 9 4.1.27 drm_crtc_helper_set_config set a new config from userspace int drm_crtc_helper_set_config struct drm_mode_set * set set mode set configuration Setup a new configuration, provided by the upper layers (either an ioctl call from userspace or internally e.g. from the fbdev support code) in set, and enable it. This is the main helper functions for drivers that implement kernel mode setting with the crtc helper functions and the assorted ->prepare, ->modeset and ->commit helper callbacks. Returns 0 on success, negative errno numbers on failure. Kernel Hackers Manual July 2017 drm_helper_connector_dpms 9 4.1.27 drm_helper_connector_dpms connector dpms helper implementation void drm_helper_connector_dpms struct drm_connector * connector int mode connector affected connector mode DPMS mode This is the main helper function provided by the crtc helper framework for implementing the DPMS connector attribute. It computes the new desired DPMS state for all encoders and crtcs in the output mesh and calls the ->dpms callback provided by the driver appropriately. Kernel Hackers Manual July 2017 drm_helper_mode_fill_fb_struct 9 4.1.27 drm_helper_mode_fill_fb_struct fill out framebuffer metadata void drm_helper_mode_fill_fb_struct struct drm_framebuffer * fb struct drm_mode_fb_cmd2 * mode_cmd fb drm_framebuffer object to fill out mode_cmd metadata from the userspace fb creation request This helper can be used in a drivers fb_create callback to pre-fill the fb's metadata fields. Kernel Hackers Manual July 2017 drm_helper_resume_force_mode 9 4.1.27 drm_helper_resume_force_mode force-restore mode setting configuration void drm_helper_resume_force_mode struct drm_device * dev dev drm_device which should be restored Drivers which use the mode setting helpers can use this function to force-restore the mode setting configuration e.g. on resume or when something else might have trampled over the hw state (like some overzealous old BIOSen tended to do). This helper doesn't provide a error return value since restoring the old config should never fail due to resource allocation issues since the driver has successfully set the restored configuration already. Hence this should boil down to the equivalent of a few dpms on calls, which also don't provide an error code. Drivers where simply restoring an old configuration again might fail (e.g. due to slight differences in allocating shared resources when the configuration is restored in a different order than when userspace set it up) need to use their own restore logic. Kernel Hackers Manual July 2017 drm_helper_crtc_mode_set 9 4.1.27 drm_helper_crtc_mode_set mode_set implementation for atomic plane helpers int drm_helper_crtc_mode_set struct drm_crtc * crtc struct drm_display_mode * mode struct drm_display_mode * adjusted_mode int x int y struct drm_framebuffer * old_fb crtc DRM CRTC mode DRM display mode which userspace requested adjusted_mode DRM display mode adjusted by ->mode_fixup callbacks x x offset of the CRTC scanout area on the underlying framebuffer y y offset of the CRTC scanout area on the underlying framebuffer old_fb previous framebuffer This function implements a callback useable as the ->mode_set callback required by the crtc helpers. Besides the atomic plane helper functions for the primary plane the driver must also provide the ->mode_set_nofb callback to set up the crtc. This is a transitional helper useful for converting drivers to the atomic interfaces. Kernel Hackers Manual July 2017 drm_helper_crtc_mode_set_base 9 4.1.27 drm_helper_crtc_mode_set_base mode_set_base implementation for atomic plane helpers int drm_helper_crtc_mode_set_base struct drm_crtc * crtc int x int y struct drm_framebuffer * old_fb crtc DRM CRTC x x offset of the CRTC scanout area on the underlying framebuffer y y offset of the CRTC scanout area on the underlying framebuffer old_fb previous framebuffer This function implements a callback useable as the ->mode_set_base used required by the crtc helpers. The driver must provide the atomic plane helper functions for the primary plane. This is a transitional helper useful for converting drivers to the atomic interfaces. The CRTC modeset helper library provides a default set_config implementation in drm_crtc_helper_set_config. Plus a few other convenience functions using the same callbacks which drivers can use to e.g. restore the modeset configuration on resume with drm_helper_resume_force_mode. The driver callbacks are mostly compatible with the atomic modeset helpers, except for the handling of the primary plane: Atomic helpers require that the primary plane is implemented as a real standalone plane and not directly tied to the CRTC state. For easier transition this library provides functions to implement the old semantics required by the CRTC helpers using the new plane and atomic helper callbacks. Drivers are strongly urged to convert to the atomic helpers (by way of first converting to the plane helpers). New drivers must not use these functions but need to implement the atomic interface instead, potentially using the atomic helpers for that. This library provides some helper code for output probing. It provides an implementation of the core connector->fill_modes interface with drm_helper_probe_single_connector_modes. It also provides support for polling connectors with a work item and for generic hotplug interrupt handling where the driver doesn't or cannot keep track of a per-connector hpd interrupt. This helper library can be used independently of the modeset helper library. Drivers can also overwrite different parts e.g. use their own hotplug handling code to avoid probing unrelated outputs. Kernel Hackers Manual July 2017 drm_helper_probe_single_connector_modes 9 4.1.27 drm_helper_probe_single_connector_modes get complete set of display modes int drm_helper_probe_single_connector_modes struct drm_connector * connector uint32_t maxX uint32_t maxY connector connector to probe maxX max width for modes maxY max height for modes Based on the helper callbacks implemented by connector try to detect all valid modes. Modes will first be added to the connector's probed_modes list, then culled (based on validity and the maxX, maxY parameters) and put into the normal modes list. Intended to be use as a generic implementation of the ->fill_modes connector vfunc for drivers that use the crtc helpers for output mode filtering and detection. The number of modes found on connector. Kernel Hackers Manual July 2017 drm_helper_probe_single_connector_modes_nomerge 9 4.1.27 drm_helper_probe_single_connector_modes_nomerge get complete set of display modes int drm_helper_probe_single_connector_modes_nomerge struct drm_connector * connector uint32_t maxX uint32_t maxY connector connector to probe maxX max width for modes maxY max height for modes This operates like drm_hehlper_probe_single_connector_modes except it replaces the mode bits instead of merging them for preferred modes. Kernel Hackers Manual July 2017 drm_kms_helper_hotplug_event 9 4.1.27 drm_kms_helper_hotplug_event fire off KMS hotplug events void drm_kms_helper_hotplug_event struct drm_device * dev dev drm_device whose connector state changed This function fires off the uevent for userspace and also calls the output_poll_changed function, which is most commonly used to inform the fbdev emulation code and allow it to update the fbcon output configuration. Drivers should call this from their hotplug handling code when a change is detected. Note that this function does not do any output detection of its own, like drm_helper_hpd_irq_event does - this is assumed to be done by the driver already. This function must be called from process context with no mode setting locks held. Kernel Hackers Manual July 2017 drm_kms_helper_poll_disable 9 4.1.27 drm_kms_helper_poll_disable disable output polling void drm_kms_helper_poll_disable struct drm_device * dev dev drm_device This function disables the output polling work. Drivers can call this helper from their device suspend implementation. It is not an error to call this even when output polling isn't enabled or arlready disabled. Kernel Hackers Manual July 2017 drm_kms_helper_poll_enable 9 4.1.27 drm_kms_helper_poll_enable re-enable output polling. void drm_kms_helper_poll_enable struct drm_device * dev dev drm_device This function re-enables the output polling work. Drivers can call this helper from their device resume implementation. It is an error to call this when the output polling support has not yet been set up. Kernel Hackers Manual July 2017 drm_kms_helper_poll_init 9 4.1.27 drm_kms_helper_poll_init initialize and enable output polling void drm_kms_helper_poll_init struct drm_device * dev dev drm_device This function intializes and then also enables output polling support for dev. Drivers which do not have reliable hotplug support in hardware can use this helper infrastructure to regularly poll such connectors for changes in their connection state. Drivers can control which connectors are polled by setting the DRM_CONNECTOR_POLL_CONNECT and DRM_CONNECTOR_POLL_DISCONNECT flags. On connectors where probing live outputs can result in visual distortion drivers should not set the DRM_CONNECTOR_POLL_DISCONNECT flag to avoid this. Connectors which have no flag or only DRM_CONNECTOR_POLL_HPD set are completely ignored by the polling logic. Note that a connector can be both polled and probed from the hotplug handler, in case the hotplug interrupt is known to be unreliable. Kernel Hackers Manual July 2017 drm_kms_helper_poll_fini 9 4.1.27 drm_kms_helper_poll_fini disable output polling and clean it up void drm_kms_helper_poll_fini struct drm_device * dev dev drm_device Kernel Hackers Manual July 2017 drm_helper_hpd_irq_event 9 4.1.27 drm_helper_hpd_irq_event hotplug processing bool drm_helper_hpd_irq_event struct drm_device * dev dev drm_device Drivers can use this helper function to run a detect cycle on all connectors which have the DRM_CONNECTOR_POLL_HPD flag set in their polled member. All other connectors are ignored, which is useful to avoid reprobing fixed panels. This helper function is useful for drivers which can't or don't track hotplug interrupts for each connector. Drivers which support hotplug interrupts for each connector individually and which have a more fine-grained detect logic should bypass this code and directly call drm_kms_helper_hotplug_event in case the connector state changed. This function must be called from process context with no mode setting locks held. Note that a connector can be both polled and probed from the hotplug handler, in case the hotplug interrupt is known to be unreliable. The fb helper functions are useful to provide an fbdev on top of a drm kernel mode setting driver. They can be used mostly independently from the crtc helper functions used by many drivers to implement the kernel mode setting interfaces. Initialization is done as a four-step process with drm_fb_helper_prepare, drm_fb_helper_init, drm_fb_helper_single_add_all_connectors and drm_fb_helper_initial_config. Drivers with fancier requirements than the default behaviour can override the third step with their own code. Teardown is done with drm_fb_helper_fini. At runtime drivers should restore the fbdev console by calling drm_fb_helper_restore_fbdev_mode from their ->lastclose callback. They should also notify the fb helper code from updates to the output configuration by calling drm_fb_helper_hotplug_event. For easier integration with the output polling code in drm_crtc_helper.c the modeset code provides a ->output_poll_changed callback. All other functions exported by the fb helper library can be used to implement the fbdev driver interface by the driver. It is possible, though perhaps somewhat tricky, to implement race-free hotplug detection using the fbdev helpers. The drm_fb_helper_prepare helper must be called first to initialize the minimum required to make hotplug detection work. Drivers also need to make sure to properly set up the dev->mode_config.funcs member. After calling drm_kms_helper_poll_init it is safe to enable interrupts and start processing hotplug events. At the same time, drivers should initialize all modeset objects such as CRTCs, encoders and connectors. To finish up the fbdev helper initialization, the drm_fb_helper_init function is called. To probe for all attached displays and set up an initial configuration using the detected hardware, drivers should call drm_fb_helper_single_add_all_connectors followed by drm_fb_helper_initial_config. Kernel Hackers Manual July 2017 drm_fb_helper_single_add_all_connectors 9 4.1.27 drm_fb_helper_single_add_all_connectors add all connectors to fbdev emulation helper int drm_fb_helper_single_add_all_connectors struct drm_fb_helper * fb_helper fb_helper fbdev initialized with drm_fb_helper_init This functions adds all the available connectors for use with the given fb_helper. This is a separate step to allow drivers to freely assign connectors to the fbdev, e.g. if some are reserved for special purposes or not adequate to be used for the fbcon. Since this is part of the initial setup before the fbdev is published, no locking is required. Kernel Hackers Manual July 2017 drm_fb_helper_debug_enter 9 4.1.27 drm_fb_helper_debug_enter implementation for ->fb_debug_enter int drm_fb_helper_debug_enter struct fb_info * info info fbdev registered by the helper Kernel Hackers Manual July 2017 drm_fb_helper_debug_leave 9 4.1.27 drm_fb_helper_debug_leave implementation for ->fb_debug_leave int drm_fb_helper_debug_leave struct fb_info * info info fbdev registered by the helper Kernel Hackers Manual July 2017 drm_fb_helper_restore_fbdev_mode_unlocked 9 4.1.27 drm_fb_helper_restore_fbdev_mode_unlocked restore fbdev configuration bool drm_fb_helper_restore_fbdev_mode_unlocked struct drm_fb_helper * fb_helper fb_helper fbcon to restore This should be called from driver's drm ->lastclose callback when implementing an fbcon on top of kms using this helper. This ensures that the user isn't greeted with a black screen when e.g. X dies. Kernel Hackers Manual July 2017 drm_fb_helper_blank 9 4.1.27 drm_fb_helper_blank implementation for ->fb_blank int drm_fb_helper_blank int blank struct fb_info * info blank desired blanking state info fbdev registered by the helper Kernel Hackers Manual July 2017 drm_fb_helper_prepare 9 4.1.27 drm_fb_helper_prepare setup a drm_fb_helper structure void drm_fb_helper_prepare struct drm_device * dev struct drm_fb_helper * helper const struct drm_fb_helper_funcs * funcs dev DRM device helper driver-allocated fbdev helper structure to set up funcs pointer to structure of functions associate with this helper Sets up the bare minimum to make the framebuffer helper usable. This is useful to implement race-free initialization of the polling helpers. Kernel Hackers Manual July 2017 drm_fb_helper_init 9 4.1.27 drm_fb_helper_init initialize a drm_fb_helper structure int drm_fb_helper_init struct drm_device * dev struct drm_fb_helper * fb_helper int crtc_count int max_conn_count dev drm device fb_helper driver-allocated fbdev helper structure to initialize crtc_count maximum number of crtcs to support in this fbdev emulation max_conn_count max connector count This allocates the structures for the fbdev helper with the given limits. Note that this won't yet touch the hardware (through the driver interfaces) nor register the fbdev. This is only done in drm_fb_helper_initial_config to allow driver writes more control over the exact init sequence. Drivers must call drm_fb_helper_prepare before calling this function. Zero if everything went ok, nonzero otherwise. Kernel Hackers Manual July 2017 drm_fb_helper_setcmap 9 4.1.27 drm_fb_helper_setcmap implementation for ->fb_setcmap int drm_fb_helper_setcmap struct fb_cmap * cmap struct fb_info * info cmap cmap to set info fbdev registered by the helper Kernel Hackers Manual July 2017 drm_fb_helper_check_var 9 4.1.27 drm_fb_helper_check_var implementation for ->fb_check_var int drm_fb_helper_check_var struct fb_var_screeninfo * var struct fb_info * info var screeninfo to check info fbdev registered by the helper Kernel Hackers Manual July 2017 drm_fb_helper_set_par 9 4.1.27 drm_fb_helper_set_par implementation for ->fb_set_par int drm_fb_helper_set_par struct fb_info * info info fbdev registered by the helper This will let fbcon do the mode init and is called at initialization time by the fbdev core when registering the driver, and later on through the hotplug callback. Kernel Hackers Manual July 2017 drm_fb_helper_pan_display 9 4.1.27 drm_fb_helper_pan_display implementation for ->fb_pan_display int drm_fb_helper_pan_display struct fb_var_screeninfo * var struct fb_info * info var updated screen information info fbdev registered by the helper Kernel Hackers Manual July 2017 drm_fb_helper_fill_fix 9 4.1.27 drm_fb_helper_fill_fix initializes fixed fbdev information void drm_fb_helper_fill_fix struct fb_info * info uint32_t pitch uint32_t depth info fbdev registered by the helper pitch desired pitch depth desired depth Helper to fill in the fixed fbdev information useful for a non-accelerated fbdev emulations. Drivers which support acceleration methods which impose additional constraints need to set up their own limits. Drivers should call this (or their equivalent setup code) from their ->fb_probe callback. Kernel Hackers Manual July 2017 drm_fb_helper_fill_var 9 4.1.27 drm_fb_helper_fill_var initalizes variable fbdev information void drm_fb_helper_fill_var struct fb_info * info struct drm_fb_helper * fb_helper uint32_t fb_width uint32_t fb_height info fbdev instance to set up fb_helper fb helper instance to use as template fb_width desired fb width fb_height desired fb height Sets up the variable fbdev metainformation from the given fb helper instance and the drm framebuffer allocated in fb_helper->fb. Drivers should call this (or their equivalent setup code) from their ->fb_probe callback after having allocated the fbdev backing storage framebuffer. Kernel Hackers Manual July 2017 drm_fb_helper_initial_config 9 4.1.27 drm_fb_helper_initial_config setup a sane initial connector configuration int drm_fb_helper_initial_config struct drm_fb_helper * fb_helper int bpp_sel fb_helper fb_helper device struct bpp_sel bpp value to use for the framebuffer configuration Scans the CRTCs and connectors and tries to put together an initial setup. At the moment, this is a cloned configuration across all heads with a new framebuffer object as the backing store. Note that this also registers the fbdev and so allows userspace to call into the driver through the fbdev interfaces. This function will call down into the ->fb_probe callback to let the driver allocate and initialize the fbdev info structure and the drm framebuffer used to back the fbdev. drm_fb_helper_fill_var and drm_fb_helper_fill_fix are provided as helpers to setup simple default values for the fbdev info structure. Zero if everything went ok, nonzero otherwise. Kernel Hackers Manual July 2017 drm_fb_helper_hotplug_event 9 4.1.27 drm_fb_helper_hotplug_event respond to a hotplug notification by probing all the outputs attached to the fb int drm_fb_helper_hotplug_event struct drm_fb_helper * fb_helper fb_helper the drm_fb_helper Scan the connectors attached to the fb_helper and try to put together a setup after *notification of a change in output configuration. Called at runtime, takes the mode config locks to be able to check/change the modeset configuration. Must be run from process context (which usually means either the output polling work or a work item launched from the driver's hotplug interrupt). Note that drivers may call this even before calling drm_fb_helper_initial_config but only aftert drm_fb_helper_init. This allows for a race-free fbcon setup and will make sure that the fbdev emulation will not miss any hotplug events. 0 on success and a non-zero error code otherwise. Kernel Hackers Manual July 2017 struct drm_fb_helper_surface_size 9 4.1.27 struct drm_fb_helper_surface_size describes fbdev size and scanout surface size struct drm_fb_helper_surface_size { u32 fb_width; u32 fb_height; u32 surface_width; u32 surface_height; u32 surface_bpp; u32 surface_depth; }; fb_width fbdev width fb_height fbdev height surface_width scanout buffer width surface_height scanout buffer height surface_bpp scanout buffer bpp surface_depth scanout buffer depth Note that the scanout surface width/height may be larger than the fbdev width/height. In case of multiple displays, the scanout surface is sized according to the largest width/height (so it is large enough for all CRTCs to scanout). But the fbdev width/height is sized to the minimum width/ height of all the displays. This ensures that fbcon fits on the smallest of the attached displays. So what is passed to drm_fb_helper_fill_var should be fb_width/fb_height, rather than the surface size. Kernel Hackers Manual July 2017 struct drm_fb_helper_funcs 9 4.1.27 struct drm_fb_helper_funcs driver callbacks for the fbdev emulation library struct drm_fb_helper_funcs { void (* gamma_set) (struct drm_crtc *crtc, u16 red, u16 green,u16 blue, int regno); void (* gamma_get) (struct drm_crtc *crtc, u16 *red, u16 *green,u16 *blue, int regno); int (* fb_probe) (struct drm_fb_helper *helper,struct drm_fb_helper_surface_size *sizes); bool (* initial_config) (struct drm_fb_helper *fb_helper,struct drm_fb_helper_crtc **crtcs,struct drm_display_mode **modes,struct drm_fb_offset *offsets,bool *enabled, int width, int height); }; gamma_set Set the given gamma lut register on the given crtc. gamma_get Read the given gamma lut register on the given crtc, used to save the current lut when force-restoring the fbdev for e.g. kdbg. fb_probe Driver callback to allocate and initialize the fbdev info structure. Furthermore it also needs to allocate the drm framebuffer used to back the fbdev. initial_config Setup an initial fbdev display configuration Driver callbacks used by the fbdev emulation helper library. These functions contain some common logic and helpers at various abstraction levels to deal with Display Port sink devices and related things like DP aux channel transfers, EDID reading over DP aux channels, decoding certain DPCD blocks, ... The DisplayPort AUX channel is an abstraction to allow generic, driver- independent access to AUX functionality. Drivers can take advantage of this by filling in the fields of the drm_dp_aux structure. Transactions are described using a hardware-independent drm_dp_aux_msg structure, which is passed into a driver's .transfer implementation. Both native and I2C-over-AUX transactions are supported. Kernel Hackers Manual July 2017 struct drm_dp_aux_msg 9 4.1.27 struct drm_dp_aux_msg DisplayPort AUX channel transaction struct drm_dp_aux_msg { unsigned int address; u8 request; u8 reply; void * buffer; size_t size; }; address address of the (first) register to access request contains the type of transaction (see DP_AUX_* macros) reply upon completion, contains the reply type of the transaction buffer pointer to a transmission or reception buffer size size of buffer Kernel Hackers Manual July 2017 struct drm_dp_aux 9 4.1.27 struct drm_dp_aux DisplayPort AUX channel struct drm_dp_aux { const char * name; struct i2c_adapter ddc; struct device * dev; struct mutex hw_mutex; ssize_t (* transfer) (struct drm_dp_aux *aux,struct drm_dp_aux_msg *msg); }; name user-visible name of this AUX channel and the I2C-over-AUX adapter ddc I2C adapter that can be used for I2C-over-AUX communication dev pointer to struct device that is the parent for this AUX channel hw_mutex internal mutex used for locking transfers transfer transfers a message representing a single AUX transaction The .dev field should be set to a pointer to the device that implements the AUX channel. The .name field may be used to specify the name of the I2C adapter. If set to NULL, dev_name of .dev will be used. Drivers provide a hardware-specific implementation of how transactions are executed via the .transfer function. A pointer to a drm_dp_aux_msg structure describing the transaction is passed into this function. Upon success, the implementation should return the number of payload bytes that were transferred, or a negative error-code on failure. Helpers propagate errors from the .transfer function, with the exception of the -EBUSY error, which causes a transaction to be retried. On a short, helpers will return -EPROTO to make it simpler to check for failure. An AUX channel can also be used to transport I2C messages to a sink. A typical application of that is to access an EDID that's present in the sink device. The .transfer function can also be used to execute such transactions. The drm_dp_aux_register_i2c_bus function registers an I2C adapter that can be passed to drm_probe_ddc. Upon removal, drivers should call drm_dp_aux_unregister_i2c_bus to remove the I2C adapter. The I2C adapter uses long transfers by default; if a partial response is received, the adapter will drop down to the size given by the partial response for this transaction only. Note that the aux helper code assumes that the .transfer function only modifies the reply field of the drm_dp_aux_msg structure. The retry logic and i2c helpers assume this is the case. Kernel Hackers Manual July 2017 drm_dp_dpcd_readb 9 4.1.27 drm_dp_dpcd_readb read a single byte from the DPCD ssize_t drm_dp_dpcd_readb struct drm_dp_aux * aux unsigned int offset u8 * valuep aux DisplayPort AUX channel offset address of the register to read valuep location where the value of the register will be stored Returns the number of bytes transferred (1) on success, or a negative error code on failure. Kernel Hackers Manual July 2017 drm_dp_dpcd_writeb 9 4.1.27 drm_dp_dpcd_writeb write a single byte to the DPCD ssize_t drm_dp_dpcd_writeb struct drm_dp_aux * aux unsigned int offset u8 value aux DisplayPort AUX channel offset address of the register to write value value to write to the register Returns the number of bytes transferred (1) on success, or a negative error code on failure. Kernel Hackers Manual July 2017 drm_dp_dpcd_read 9 4.1.27 drm_dp_dpcd_read read a series of bytes from the DPCD ssize_t drm_dp_dpcd_read struct drm_dp_aux * aux unsigned int offset void * buffer size_t size aux DisplayPort AUX channel offset address of the (first) register to read buffer buffer to store the register values size number of bytes in buffer Returns the number of bytes transferred on success, or a negative error code on failure. -EIO is returned if the request was NAKed by the sink or if the retry count was exceeded. If not all bytes were transferred, this function returns -EPROTO. Errors from the underlying AUX channel transfer function, with the exception of -EBUSY (which causes the transaction to be retried), are propagated to the caller. Kernel Hackers Manual July 2017 drm_dp_dpcd_write 9 4.1.27 drm_dp_dpcd_write write a series of bytes to the DPCD ssize_t drm_dp_dpcd_write struct drm_dp_aux * aux unsigned int offset void * buffer size_t size aux DisplayPort AUX channel offset address of the (first) register to write buffer buffer containing the values to write size number of bytes in buffer Returns the number of bytes transferred on success, or a negative error code on failure. -EIO is returned if the request was NAKed by the sink or if the retry count was exceeded. If not all bytes were transferred, this function returns -EPROTO. Errors from the underlying AUX channel transfer function, with the exception of -EBUSY (which causes the transaction to be retried), are propagated to the caller. Kernel Hackers Manual July 2017 drm_dp_dpcd_read_link_status 9 4.1.27 drm_dp_dpcd_read_link_status read DPCD link status (bytes 0x202-0x207) int drm_dp_dpcd_read_link_status struct drm_dp_aux * aux u8 status[DP_LINK_STATUS_SIZE] aux DisplayPort AUX channel status[DP_LINK_STATUS_SIZE] buffer to store the link status in (must be at least 6 bytes) Returns the number of bytes transferred on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_dp_link_probe 9 4.1.27 drm_dp_link_probe probe a DisplayPort link for capabilities int drm_dp_link_probe struct drm_dp_aux * aux struct drm_dp_link * link aux DisplayPort AUX channel link pointer to structure in which to return link capabilities The structure filled in by this function can usually be passed directly into drm_dp_link_power_up and drm_dp_link_configure to power up and configure the link based on the link's capabilities. Returns 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_dp_link_power_up 9 4.1.27 drm_dp_link_power_up power up a DisplayPort link int drm_dp_link_power_up struct drm_dp_aux * aux struct drm_dp_link * link aux DisplayPort AUX channel link pointer to a structure containing the link configuration Returns 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_dp_link_power_down 9 4.1.27 drm_dp_link_power_down power down a DisplayPort link int drm_dp_link_power_down struct drm_dp_aux * aux struct drm_dp_link * link aux DisplayPort AUX channel link pointer to a structure containing the link configuration Returns 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_dp_link_configure 9 4.1.27 drm_dp_link_configure configure a DisplayPort link int drm_dp_link_configure struct drm_dp_aux * aux struct drm_dp_link * link aux DisplayPort AUX channel link pointer to a structure containing the link configuration Returns 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_dp_aux_register 9 4.1.27 drm_dp_aux_register initialise and register aux channel int drm_dp_aux_register struct drm_dp_aux * aux aux DisplayPort AUX channel Returns 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_dp_aux_unregister 9 4.1.27 drm_dp_aux_unregister unregister an AUX adapter void drm_dp_aux_unregister struct drm_dp_aux * aux aux DisplayPort AUX channel These functions contain parts of the DisplayPort 1.2a MultiStream Transport protocol. The helpers contain a topology manager and bandwidth manager. The helpers encapsulate the sending and received of sideband msgs. Kernel Hackers Manual July 2017 struct drm_dp_vcpi 9 4.1.27 struct drm_dp_vcpi Virtual Channel Payload Identifier struct drm_dp_vcpi { int vcpi; int pbn; int aligned_pbn; int num_slots; }; vcpi Virtual channel ID. pbn Payload Bandwidth Number for this channel aligned_pbn PBN aligned with slot size num_slots number of slots for this PBN Kernel Hackers Manual July 2017 struct drm_dp_mst_port 9 4.1.27 struct drm_dp_mst_port MST port struct drm_dp_mst_port { struct kref kref; u8 port_num; bool input; bool mcs; bool ddps; u8 pdt; bool ldps; u8 dpcd_rev; u8 num_sdp_streams; u8 num_sdp_stream_sinks; uint16_t available_pbn; struct list_head next; struct drm_dp_mst_branch * mstb; struct drm_dp_aux aux; struct drm_dp_mst_branch * parent; struct drm_dp_vcpi vcpi; struct drm_connector * connector; struct drm_dp_mst_topology_mgr * mgr; }; kref reference count for this port. port_num port number input if this port is an input port. mcs message capability status - DP 1.2 spec. ddps DisplayPort Device Plug Status - DP 1.2 pdt Peer Device Type ldps Legacy Device Plug Status dpcd_rev DPCD revision of device on this port num_sdp_streams Number of simultaneous streams num_sdp_stream_sinks Number of stream sinks available_pbn Available bandwidth for this port. next link to next port on this branch device mstb branch device attach below this port aux i2c aux transport to talk to device connected to this port. parent branch device parent of this port vcpi Virtual Channel Payload info for this port. connector DRM connector this port is connected to. mgr topology manager this port lives under. This structure represents an MST port endpoint on a device somewhere in the MST topology. Kernel Hackers Manual July 2017 struct drm_dp_mst_branch 9 4.1.27 struct drm_dp_mst_branch MST branch device. struct drm_dp_mst_branch { struct kref kref; u8 rad[8]; u8 lct; int num_ports; int msg_slots; struct list_head ports; struct drm_dp_mst_port * port_parent; struct drm_dp_mst_topology_mgr * mgr; struct drm_dp_sideband_msg_tx * tx_slots[2]; int last_seqno; bool link_address_sent; u8 guid[16]; }; kref reference count for this port. rad[8] Relative Address to talk to this branch device. lct Link count total to talk to this branch device. num_ports number of ports on the branch. msg_slots one bit per transmitted msg slot. ports linked list of ports on this branch. port_parent pointer to the port parent, NULL if toplevel. mgr topology manager for this branch device. tx_slots[2] transmission slots for this device. last_seqno last sequence number used to talk to this. link_address_sent if a link address message has been sent to this device yet. guid[16] guid for DP 1.2 branch device. port under this branch can be identified by port #. This structure represents an MST branch device, there is one primary branch device at the root, along with any other branches connected to downstream port of parent branches. Kernel Hackers Manual July 2017 struct drm_dp_mst_topology_mgr 9 4.1.27 struct drm_dp_mst_topology_mgr DisplayPort MST manager struct drm_dp_mst_topology_mgr { struct device * dev; struct drm_dp_mst_topology_cbs * cbs; struct drm_dp_aux * aux; int max_payloads; int conn_base_id; struct drm_dp_sideband_msg_rx down_rep_recv; struct drm_dp_sideband_msg_rx up_req_recv; struct mutex lock; bool mst_state; struct drm_dp_mst_branch * mst_primary; u8 dpcd[DP_RECEIVER_CAP_SIZE]; int pbn_div; }; dev device pointer for adding i2c devices etc. cbs callbacks for connector addition and destruction. max_dpcd_transaction_bytes - maximum number of bytes to read/write in one go. aux aux channel for the DP connector. max_payloads maximum number of payloads the GPU can generate. conn_base_id DRM connector ID this mgr is connected to. down_rep_recv msg receiver state for down replies. up_req_recv msg receiver state for up requests. lock protects mst state, primary, dpcd. mst_state if this manager is enabled for an MST capable port. mst_primary pointer to the primary branch device. dpcd[DP_RECEIVER_CAP_SIZE] cache of DPCD for primary port. pbn_div PBN to slots divisor. This struct represents the toplevel displayport MST topology manager. There should be one instance of this for every MST capable DP connector on the GPU. Kernel Hackers Manual July 2017 drm_dp_update_payload_part1 9 4.1.27 drm_dp_update_payload_part1 Execute payload update part 1 int drm_dp_update_payload_part1 struct drm_dp_mst_topology_mgr * mgr mgr manager to use. This iterates over all proposed virtual channels, and tries to allocate space in the link for them. For 0->slots transitions, this step just writes the VCPI to the MST device. For slots->0 transitions, this writes the updated VCPIs and removes the remote VC payloads. after calling this the driver should generate ACT and payload packets. Kernel Hackers Manual July 2017 drm_dp_update_payload_part2 9 4.1.27 drm_dp_update_payload_part2 Execute payload update part 2 int drm_dp_update_payload_part2 struct drm_dp_mst_topology_mgr * mgr mgr manager to use. This iterates over all proposed virtual channels, and tries to allocate space in the link for them. For 0->slots transitions, this step writes the remote VC payload commands. For slots->0 this just resets some internal state. Kernel Hackers Manual July 2017 drm_dp_mst_topology_mgr_set_mst 9 4.1.27 drm_dp_mst_topology_mgr_set_mst Set the MST state for a topology manager int drm_dp_mst_topology_mgr_set_mst struct drm_dp_mst_topology_mgr * mgr bool mst_state mgr manager to set state for mst_state true to enable MST on this connector - false to disable. This is called by the driver when it detects an MST capable device plugged into a DP MST capable port, or when a DP MST capable device is unplugged. Kernel Hackers Manual July 2017 drm_dp_mst_topology_mgr_suspend 9 4.1.27 drm_dp_mst_topology_mgr_suspend suspend the MST manager void drm_dp_mst_topology_mgr_suspend struct drm_dp_mst_topology_mgr * mgr mgr manager to suspend This function tells the MST device that we can't handle UP messages anymore. This should stop it from sending any since we are suspended. Kernel Hackers Manual July 2017 drm_dp_mst_topology_mgr_resume 9 4.1.27 drm_dp_mst_topology_mgr_resume resume the MST manager int drm_dp_mst_topology_mgr_resume struct drm_dp_mst_topology_mgr * mgr mgr manager to resume This will fetch DPCD and see if the device is still there, if it is, it will rewrite the MSTM control bits, and return. if the device fails this returns -1, and the driver should do a full MST reprobe, in case we were undocked. Kernel Hackers Manual July 2017 drm_dp_mst_hpd_irq 9 4.1.27 drm_dp_mst_hpd_irq MST hotplug IRQ notify int drm_dp_mst_hpd_irq struct drm_dp_mst_topology_mgr * mgr u8 * esi bool * handled mgr manager to notify irq for. esi 4 bytes from SINK_COUNT_ESI handled whether the hpd interrupt was consumed or not This should be called from the driver when it detects a short IRQ, along with the value of the DEVICE_SERVICE_IRQ_VECTOR_ESI0. The topology manager will process the sideband messages received as a result of this. Kernel Hackers Manual July 2017 drm_dp_mst_detect_port 9 4.1.27 drm_dp_mst_detect_port get connection status for an MST port enum drm_connector_status drm_dp_mst_detect_port struct drm_connector * connector struct drm_dp_mst_topology_mgr * mgr struct drm_dp_mst_port * port connector -- undescribed -- mgr manager for this port port unverified pointer to a port This returns the current connection state for a port. It validates the port pointer still exists so the caller doesn't require a reference Kernel Hackers Manual July 2017 drm_dp_mst_get_edid 9 4.1.27 drm_dp_mst_get_edid get EDID for an MST port struct edid * drm_dp_mst_get_edid struct drm_connector * connector struct drm_dp_mst_topology_mgr * mgr struct drm_dp_mst_port * port connector toplevel connector to get EDID for mgr manager for this port port unverified pointer to a port. This returns an EDID for the port connected to a connector, It validates the pointer still exists so the caller doesn't require a reference. Kernel Hackers Manual July 2017 drm_dp_find_vcpi_slots 9 4.1.27 drm_dp_find_vcpi_slots find slots for this PBN value int drm_dp_find_vcpi_slots struct drm_dp_mst_topology_mgr * mgr int pbn mgr manager to use pbn payload bandwidth to convert into slots. Kernel Hackers Manual July 2017 drm_dp_mst_allocate_vcpi 9 4.1.27 drm_dp_mst_allocate_vcpi Allocate a virtual channel bool drm_dp_mst_allocate_vcpi struct drm_dp_mst_topology_mgr * mgr struct drm_dp_mst_port * port int pbn int * slots mgr manager for this port port port to allocate a virtual channel for. pbn payload bandwidth number to request slots returned number of slots for this PBN. Kernel Hackers Manual July 2017 drm_dp_mst_reset_vcpi_slots 9 4.1.27 drm_dp_mst_reset_vcpi_slots Reset number of slots to 0 for VCPI void drm_dp_mst_reset_vcpi_slots struct drm_dp_mst_topology_mgr * mgr struct drm_dp_mst_port * port mgr manager for this port port unverified pointer to a port. This just resets the number of slots for the ports VCPI for later programming. Kernel Hackers Manual July 2017 drm_dp_mst_deallocate_vcpi 9 4.1.27 drm_dp_mst_deallocate_vcpi deallocate a VCPI void drm_dp_mst_deallocate_vcpi struct drm_dp_mst_topology_mgr * mgr struct drm_dp_mst_port * port mgr manager for this port port unverified port to deallocate vcpi for Kernel Hackers Manual July 2017 drm_dp_check_act_status 9 4.1.27 drm_dp_check_act_status Check ACT handled status. int drm_dp_check_act_status struct drm_dp_mst_topology_mgr * mgr mgr manager to use Check the payload status bits in the DPCD for ACT handled completion. Kernel Hackers Manual July 2017 drm_dp_calc_pbn_mode 9 4.1.27 drm_dp_calc_pbn_mode Calculate the PBN for a mode. int drm_dp_calc_pbn_mode int clock int bpp clock dot clock for the mode bpp bpp for the mode. This uses the formula in the spec to calculate the PBN value for a mode. Kernel Hackers Manual July 2017 drm_dp_mst_dump_topology 9 4.1.27 drm_dp_mst_dump_topology void drm_dp_mst_dump_topology struct seq_file * m struct drm_dp_mst_topology_mgr * mgr m seq_file to dump output to mgr manager to dump current topology for. helper to dump MST topology to a seq file for debugfs. Kernel Hackers Manual July 2017 drm_dp_mst_topology_mgr_init 9 4.1.27 drm_dp_mst_topology_mgr_init initialise a topology manager int drm_dp_mst_topology_mgr_init struct drm_dp_mst_topology_mgr * mgr struct device * dev struct drm_dp_aux * aux int max_dpcd_transaction_bytes int max_payloads int conn_base_id mgr manager struct to initialise dev device providing this structure - for i2c addition. aux DP helper aux channel to talk to this device max_dpcd_transaction_bytes hw specific DPCD transaction limit max_payloads maximum number of payloads this GPU can source conn_base_id the connector object ID the MST device is connected to. Return 0 for success, or negative error code on failure Kernel Hackers Manual July 2017 drm_dp_mst_topology_mgr_destroy 9 4.1.27 drm_dp_mst_topology_mgr_destroy destroy topology manager. void drm_dp_mst_topology_mgr_destroy struct drm_dp_mst_topology_mgr * mgr mgr manager to destroy These functions contain some common logic and helpers to deal with MIPI DSI peripherals. Helpers are provided for a number of standard MIPI DSI command as well as a subset of the MIPI DCS command set. Kernel Hackers Manual July 2017 struct mipi_dsi_msg 9 4.1.27 struct mipi_dsi_msg read/write DSI buffer struct mipi_dsi_msg { u8 channel; u8 type; u16 flags; size_t tx_len; const void * tx_buf; size_t rx_len; void * rx_buf; }; channel virtual channel id type payload data type flags flags controlling this message transmission tx_len length of tx_buf tx_buf data to be written rx_len length of rx_buf rx_buf data to be read, or NULL Kernel Hackers Manual July 2017 struct mipi_dsi_packet 9 4.1.27 struct mipi_dsi_packet represents a MIPI DSI packet in protocol format struct mipi_dsi_packet { size_t size; u8 header[4]; size_t payload_length; const u8 * payload; }; size size (in bytes) of the packet header[4] the four bytes that make up the header (Data ID, Word Count or Packet Data, and ECC) payload_length number of bytes in the payload payload a pointer to a buffer containing the payload, if any Kernel Hackers Manual July 2017 struct mipi_dsi_host_ops 9 4.1.27 struct mipi_dsi_host_ops DSI bus operations struct mipi_dsi_host_ops { int (* attach) (struct mipi_dsi_host *host,struct mipi_dsi_device *dsi); int (* detach) (struct mipi_dsi_host *host,struct mipi_dsi_device *dsi); ssize_t (* transfer) (struct mipi_dsi_host *host,const struct mipi_dsi_msg *msg); }; attach attach DSI device to DSI host detach detach DSI device from DSI host transfer transmit a DSI packet DSI packets transmitted by .transfer are passed in as mipi_dsi_msg structures. This structure contains information about the type of packet being transmitted as well as the transmit and receive buffers. When an error is encountered during transmission, this function will return a negative error code. On success it shall return the number of bytes transmitted for write packets or the number of bytes received for read packets. Note that typically DSI packet transmission is atomic, so the .transfer function will seldomly return anything other than the number of bytes contained in the transmit buffer on success. Kernel Hackers Manual July 2017 struct mipi_dsi_host 9 4.1.27 struct mipi_dsi_host DSI host device struct mipi_dsi_host { struct device * dev; const struct mipi_dsi_host_ops * ops; }; dev driver model device node for this DSI host ops DSI host operations Kernel Hackers Manual July 2017 struct mipi_dsi_device 9 4.1.27 struct mipi_dsi_device DSI peripheral device struct mipi_dsi_device { struct mipi_dsi_host * host; struct device dev; unsigned int channel; unsigned int lanes; enum mipi_dsi_pixel_format format; unsigned long mode_flags; }; host DSI host for this peripheral dev driver model device node for this peripheral channel virtual channel assigned to the peripheral lanes number of active data lanes format pixel format for video mode mode_flags DSI operation mode related flags Kernel Hackers Manual July 2017 enum mipi_dsi_dcs_tear_mode 9 4.1.27 enum mipi_dsi_dcs_tear_mode Tearing Effect Output Line mode enum mipi_dsi_dcs_tear_mode { MIPI_DSI_DCS_TEAR_MODE_VBLANK, MIPI_DSI_DCS_TEAR_MODE_VHBLANK }; MIPI_DSI_DCS_TEAR_MODE_VBLANK the TE output line consists of V-Blanking information only MIPI_DSI_DCS_TEAR_MODE_VHBLANK the TE output line consists of both V-Blanking and H-Blanking information Kernel Hackers Manual July 2017 struct mipi_dsi_driver 9 4.1.27 struct mipi_dsi_driver DSI driver struct mipi_dsi_driver { struct device_driver driver; int(* probe) (struct mipi_dsi_device *dsi); int(* remove) (struct mipi_dsi_device *dsi); void (* shutdown) (struct mipi_dsi_device *dsi); }; driver device driver model driver probe callback for device binding remove callback for device unbinding shutdown called at shutdown time to quiesce the device Kernel Hackers Manual July 2017 of_find_mipi_dsi_device_by_node 9 4.1.27 of_find_mipi_dsi_device_by_node find the MIPI DSI device matching a device tree node struct mipi_dsi_device * of_find_mipi_dsi_device_by_node struct device_node * np np device tree node A pointer to the MIPI DSI device corresponding to np or NULL if no such device exists (or has not been registered yet). Kernel Hackers Manual July 2017 mipi_dsi_attach 9 4.1.27 mipi_dsi_attach attach a DSI device to its DSI host int mipi_dsi_attach struct mipi_dsi_device * dsi dsi DSI peripheral Kernel Hackers Manual July 2017 mipi_dsi_detach 9 4.1.27 mipi_dsi_detach detach a DSI device from its DSI host int mipi_dsi_detach struct mipi_dsi_device * dsi dsi DSI peripheral Kernel Hackers Manual July 2017 mipi_dsi_packet_format_is_short 9 4.1.27 mipi_dsi_packet_format_is_short check if a packet is of the short format bool mipi_dsi_packet_format_is_short u8 type type MIPI DSI data type of the packet true if the packet for the given data type is a short packet, false otherwise. Kernel Hackers Manual July 2017 mipi_dsi_packet_format_is_long 9 4.1.27 mipi_dsi_packet_format_is_long check if a packet is of the long format bool mipi_dsi_packet_format_is_long u8 type type MIPI DSI data type of the packet true if the packet for the given data type is a long packet, false otherwise. Kernel Hackers Manual July 2017 mipi_dsi_create_packet 9 4.1.27 mipi_dsi_create_packet create a packet from a message according to the DSI protocol int mipi_dsi_create_packet struct mipi_dsi_packet * packet const struct mipi_dsi_msg * msg packet pointer to a DSI packet structure msg message to translate into a packet 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_generic_write 9 4.1.27 mipi_dsi_generic_write transmit data using a generic write packet ssize_t mipi_dsi_generic_write struct mipi_dsi_device * dsi const void * payload size_t size dsi DSI peripheral device payload buffer containing the payload size size of payload buffer This function will automatically choose the right data type depending on the payload length. The number of bytes transmitted on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_generic_read 9 4.1.27 mipi_dsi_generic_read receive data using a generic read packet ssize_t mipi_dsi_generic_read struct mipi_dsi_device * dsi const void * params size_t num_params void * data size_t size dsi DSI peripheral device params buffer containing the request parameters num_params number of request parameters data buffer in which to return the received data size size of receive buffer This function will automatically choose the right data type depending on the number of parameters passed in. The number of bytes successfully read or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_write_buffer 9 4.1.27 mipi_dsi_dcs_write_buffer transmit a DCS command with payload ssize_t mipi_dsi_dcs_write_buffer struct mipi_dsi_device * dsi const void * data size_t len dsi DSI peripheral device data buffer containing data to be transmitted len size of transmission buffer This function will automatically choose the right data type depending on the command payload length. The number of bytes successfully transmitted or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_write 9 4.1.27 mipi_dsi_dcs_write send DCS write command ssize_t mipi_dsi_dcs_write struct mipi_dsi_device * dsi u8 cmd const void * data size_t len dsi DSI peripheral device cmd DCS command data buffer containing the command payload len command payload length This function will automatically choose the right data type depending on the command payload length. The number of bytes successfully transmitted or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_read 9 4.1.27 mipi_dsi_dcs_read send DCS read request command ssize_t mipi_dsi_dcs_read struct mipi_dsi_device * dsi u8 cmd void * data size_t len dsi DSI peripheral device cmd DCS command data buffer in which to receive data len size of receive buffer The number of bytes read or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_nop 9 4.1.27 mipi_dsi_dcs_nop send DCS nop packet int mipi_dsi_dcs_nop struct mipi_dsi_device * dsi dsi DSI peripheral device 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_soft_reset 9 4.1.27 mipi_dsi_dcs_soft_reset perform a software reset of the display module int mipi_dsi_dcs_soft_reset struct mipi_dsi_device * dsi dsi DSI peripheral device 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_get_power_mode 9 4.1.27 mipi_dsi_dcs_get_power_mode query the display module's current power mode int mipi_dsi_dcs_get_power_mode struct mipi_dsi_device * dsi u8 * mode dsi DSI peripheral device mode return location for the current power mode 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_get_pixel_format 9 4.1.27 mipi_dsi_dcs_get_pixel_format gets the pixel format for the RGB image data used by the interface int mipi_dsi_dcs_get_pixel_format struct mipi_dsi_device * dsi u8 * format dsi DSI peripheral device format return location for the pixel format 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_enter_sleep_mode 9 4.1.27 mipi_dsi_dcs_enter_sleep_mode disable all unnecessary blocks inside the display module except interface communication int mipi_dsi_dcs_enter_sleep_mode struct mipi_dsi_device * dsi dsi DSI peripheral device 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_exit_sleep_mode 9 4.1.27 mipi_dsi_dcs_exit_sleep_mode enable all blocks inside the display module int mipi_dsi_dcs_exit_sleep_mode struct mipi_dsi_device * dsi dsi DSI peripheral device 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_set_display_off 9 4.1.27 mipi_dsi_dcs_set_display_off stop displaying the image data on the display device int mipi_dsi_dcs_set_display_off struct mipi_dsi_device * dsi dsi DSI peripheral device 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_set_display_on 9 4.1.27 mipi_dsi_dcs_set_display_on start displaying the image data on the display device int mipi_dsi_dcs_set_display_on struct mipi_dsi_device * dsi dsi DSI peripheral device 0 on success or a negative error code on failure Kernel Hackers Manual July 2017 mipi_dsi_dcs_set_column_address 9 4.1.27 mipi_dsi_dcs_set_column_address define the column extent of the frame memory accessed by the host processor int mipi_dsi_dcs_set_column_address struct mipi_dsi_device * dsi u16 start u16 end dsi DSI peripheral device start first column of frame memory end last column of frame memory 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_set_page_address 9 4.1.27 mipi_dsi_dcs_set_page_address define the page extent of the frame memory accessed by the host processor int mipi_dsi_dcs_set_page_address struct mipi_dsi_device * dsi u16 start u16 end dsi DSI peripheral device start first page of frame memory end last page of frame memory 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_dcs_set_tear_off 9 4.1.27 mipi_dsi_dcs_set_tear_off turn off the display module's Tearing Effect output signal on the TE signal line int mipi_dsi_dcs_set_tear_off struct mipi_dsi_device * dsi dsi DSI peripheral device 0 on success or a negative error code on failure Kernel Hackers Manual July 2017 mipi_dsi_dcs_set_tear_on 9 4.1.27 mipi_dsi_dcs_set_tear_on turn on the display module's Tearing Effect output signal on the TE signal line. int mipi_dsi_dcs_set_tear_on struct mipi_dsi_device * dsi enum mipi_dsi_dcs_tear_mode mode dsi DSI peripheral device mode the Tearing Effect Output Line mode 0 on success or a negative error code on failure Kernel Hackers Manual July 2017 mipi_dsi_dcs_set_pixel_format 9 4.1.27 mipi_dsi_dcs_set_pixel_format sets the pixel format for the RGB image data used by the interface int mipi_dsi_dcs_set_pixel_format struct mipi_dsi_device * dsi u8 format dsi DSI peripheral device format pixel format 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_driver_register_full 9 4.1.27 mipi_dsi_driver_register_full register a driver for DSI devices int mipi_dsi_driver_register_full struct mipi_dsi_driver * drv struct module * owner drv DSI driver structure owner owner module 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 mipi_dsi_driver_unregister 9 4.1.27 mipi_dsi_driver_unregister unregister a driver for DSI devices void mipi_dsi_driver_unregister struct mipi_dsi_driver * drv drv DSI driver structure 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_edid_header_is_valid 9 4.1.27 drm_edid_header_is_valid sanity check the header of the base EDID block int drm_edid_header_is_valid const u8 * raw_edid raw_edid pointer to raw base EDID block Sanity check the header of the base EDID block. 8 if the header is perfect, down to 0 if it's totally wrong. Kernel Hackers Manual July 2017 drm_edid_block_valid 9 4.1.27 drm_edid_block_valid Sanity check the EDID block (base or extension) bool drm_edid_block_valid u8 * raw_edid int block bool print_bad_edid raw_edid pointer to raw EDID block block type of block to validate (0 for base, extension otherwise) print_bad_edid if true, dump bad EDID blocks to the console Validate a base or extension EDID block and optionally dump bad blocks to the console. True if the block is valid, false otherwise. Kernel Hackers Manual July 2017 drm_edid_is_valid 9 4.1.27 drm_edid_is_valid sanity check EDID data bool drm_edid_is_valid struct edid * edid edid EDID data Sanity-check an entire EDID record (including extensions) True if the EDID data is valid, false otherwise. Kernel Hackers Manual July 2017 drm_do_get_edid 9 4.1.27 drm_do_get_edid get EDID data using a custom EDID block read function struct edid * drm_do_get_edid struct drm_connector * connector int (*get_edid_block) void *data, u8 *buf, unsigned int block, size_t len void * data connector connector we're probing get_edid_block EDID block read function data private data passed to the block read function When the I2C adapter connected to the DDC bus is hidden behind a device that exposes a different interface to read EDID blocks this function can be used to get EDID data using a custom block read function. As in the general case the DDC bus is accessible by the kernel at the I2C level, drivers must make all reasonable efforts to expose it as an I2C adapter and use drm_get_edid instead of abusing this function. Pointer to valid EDID or NULL if we couldn't find any. Kernel Hackers Manual July 2017 drm_probe_ddc 9 4.1.27 drm_probe_ddc probe DDC presence bool drm_probe_ddc struct i2c_adapter * adapter adapter I2C adapter to probe True on success, false on failure. Kernel Hackers Manual July 2017 drm_get_edid 9 4.1.27 drm_get_edid get EDID data, if available struct edid * drm_get_edid struct drm_connector * connector struct i2c_adapter * adapter connector connector we're probing adapter I2C adapter to use for DDC Poke the given I2C channel to grab EDID data if possible. If found, attach it to the connector. Pointer to valid EDID or NULL if we couldn't find any. Kernel Hackers Manual July 2017 drm_edid_duplicate 9 4.1.27 drm_edid_duplicate duplicate an EDID and the extensions struct edid * drm_edid_duplicate const struct edid * edid edid EDID to duplicate Pointer to duplicated EDID or NULL on allocation failure. Kernel Hackers Manual July 2017 drm_match_cea_mode 9 4.1.27 drm_match_cea_mode look for a CEA mode matching given mode u8 drm_match_cea_mode const struct drm_display_mode * to_match to_match display mode The CEA Video ID (VIC) of the mode or 0 if it isn't a CEA-861 mode. Kernel Hackers Manual July 2017 drm_get_cea_aspect_ratio 9 4.1.27 drm_get_cea_aspect_ratio get the picture aspect ratio corresponding to the input VIC from the CEA mode list enum hdmi_picture_aspect drm_get_cea_aspect_ratio const u8 video_code video_code ID given to each of the CEA modes Returns picture aspect ratio Kernel Hackers Manual July 2017 drm_edid_to_eld 9 4.1.27 drm_edid_to_eld build ELD from EDID void drm_edid_to_eld struct drm_connector * connector struct edid * edid connector connector corresponding to the HDMI/DP sink edid EDID to parse Fill the ELD (EDID-Like Data) buffer for passing to the audio driver. The Conn_Type, HDCP and Port_ID ELD fields are left for the graphics driver to fill in. Kernel Hackers Manual July 2017 drm_edid_to_sad 9 4.1.27 drm_edid_to_sad extracts SADs from EDID int drm_edid_to_sad struct edid * edid struct cea_sad ** sads edid EDID to parse sads pointer that will be set to the extracted SADs Looks for CEA EDID block and extracts SADs (Short Audio Descriptors) from it. The returned pointer needs to be freed using kfree. The number of found SADs or negative number on error. Kernel Hackers Manual July 2017 drm_edid_to_speaker_allocation 9 4.1.27 drm_edid_to_speaker_allocation extracts Speaker Allocation Data Blocks from EDID int drm_edid_to_speaker_allocation struct edid * edid u8 ** sadb edid EDID to parse sadb pointer to the speaker block Looks for CEA EDID block and extracts the Speaker Allocation Data Block from it. The returned pointer needs to be freed using kfree. The number of found Speaker Allocation Blocks or negative number on error. Kernel Hackers Manual July 2017 drm_av_sync_delay 9 4.1.27 drm_av_sync_delay compute the HDMI/DP sink audio-video sync delay int drm_av_sync_delay struct drm_connector * connector struct drm_display_mode * mode connector connector associated with the HDMI/DP sink mode the display mode The HDMI/DP sink's audio-video sync delay in milliseconds or 0 if the sink doesn't support audio or video. Kernel Hackers Manual July 2017 drm_select_eld 9 4.1.27 drm_select_eld select one ELD from multiple HDMI/DP sinks struct drm_connector * drm_select_eld struct drm_encoder * encoder struct drm_display_mode * mode encoder the encoder just changed display mode mode the adjusted display mode It's possible for one encoder to be associated with multiple HDMI/DP sinks. The policy is now hard coded to simply use the first HDMI/DP sink's ELD. The connector associated with the first HDMI/DP sink that has ELD attached to it. Kernel Hackers Manual July 2017 drm_detect_hdmi_monitor 9 4.1.27 drm_detect_hdmi_monitor detect whether monitor is HDMI bool drm_detect_hdmi_monitor struct edid * edid edid monitor EDID information Parse the CEA extension according to CEA-861-B. True if the monitor is HDMI, false if not or unknown. Kernel Hackers Manual July 2017 drm_detect_monitor_audio 9 4.1.27 drm_detect_monitor_audio check monitor audio capability bool drm_detect_monitor_audio struct edid * edid edid EDID block to scan Monitor should have CEA extension block. If monitor has 'basic audio', but no CEA audio blocks, it's 'basic audio' only. If there is any audio extension block and supported audio format, assume at least 'basic audio' support, even if 'basic audio' is not defined in EDID. True if the monitor supports audio, false otherwise. Kernel Hackers Manual July 2017 drm_rgb_quant_range_selectable 9 4.1.27 drm_rgb_quant_range_selectable is RGB quantization range selectable? bool drm_rgb_quant_range_selectable struct edid * edid edid EDID block to scan Check whether the monitor reports the RGB quantization range selection as supported. The AVI infoframe can then be used to inform the monitor which quantization range (full or limited) is used. True if the RGB quantization range is selectable, false otherwise. Kernel Hackers Manual July 2017 drm_add_edid_modes 9 4.1.27 drm_add_edid_modes add modes from EDID data, if available int drm_add_edid_modes struct drm_connector * connector struct edid * edid connector connector we're probing edid EDID data Add the specified modes to the connector's mode list. The number of modes added or 0 if we couldn't find any. Kernel Hackers Manual July 2017 drm_add_modes_noedid 9 4.1.27 drm_add_modes_noedid add modes for the connectors without EDID int drm_add_modes_noedid struct drm_connector * connector int hdisplay int vdisplay connector connector we're probing hdisplay the horizontal display limit vdisplay the vertical display limit Add the specified modes to the connector's mode list. Only when the hdisplay/vdisplay is not beyond the given limit, it will be added. The number of modes added or 0 if we couldn't find any. Kernel Hackers Manual July 2017 drm_set_preferred_mode 9 4.1.27 drm_set_preferred_mode Sets the preferred mode of a connector void drm_set_preferred_mode struct drm_connector * connector int hpref int vpref connector connector whose mode list should be processed hpref horizontal resolution of preferred mode vpref vertical resolution of preferred mode Marks a mode as preferred if it matches the resolution specified by hpref and vpref. Kernel Hackers Manual July 2017 drm_hdmi_avi_infoframe_from_display_mode 9 4.1.27 drm_hdmi_avi_infoframe_from_display_mode fill an HDMI AVI infoframe with data from a DRM display mode int drm_hdmi_avi_infoframe_from_display_mode struct hdmi_avi_infoframe * frame const struct drm_display_mode * mode frame HDMI AVI infoframe mode DRM display mode 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_hdmi_vendor_infoframe_from_display_mode 9 4.1.27 drm_hdmi_vendor_infoframe_from_display_mode fill an HDMI infoframe with data from a DRM display mode int drm_hdmi_vendor_infoframe_from_display_mode struct hdmi_vendor_infoframe * frame const struct drm_display_mode * mode frame HDMI vendor infoframe mode DRM display mode Note that there's is a need to send HDMI vendor infoframes only when using a 4k or stereoscopic 3D mode. So when giving any other mode as input this function will return -EINVAL, error that can be safely ignored. 0 on success or a negative error code on failure. Utility functions to help manage rectangular areas for clipping, scaling, etc. calculations. Kernel Hackers Manual July 2017 struct drm_rect 9 4.1.27 struct drm_rect two dimensional rectangle struct drm_rect { int x1; int y1; int x2; int y2; }; x1 horizontal starting coordinate (inclusive) y1 vertical starting coordinate (inclusive) x2 horizontal ending coordinate (exclusive) y2 vertical ending coordinate (exclusive) Kernel Hackers Manual July 2017 drm_rect_adjust_size 9 4.1.27 drm_rect_adjust_size adjust the size of the rectangle void drm_rect_adjust_size struct drm_rect * r int dw int dh r rectangle to be adjusted dw horizontal adjustment dh vertical adjustment Change the size of rectangle r by dw in the horizontal direction, and by dh in the vertical direction, while keeping the center of r stationary. Positive dw and dh increase the size, negative values decrease it. Kernel Hackers Manual July 2017 drm_rect_translate 9 4.1.27 drm_rect_translate translate the rectangle void drm_rect_translate struct drm_rect * r int dx int dy r rectangle to be tranlated dx horizontal translation dy vertical translation Move rectangle r by dx in the horizontal direction, and by dy in the vertical direction. Kernel Hackers Manual July 2017 drm_rect_downscale 9 4.1.27 drm_rect_downscale downscale a rectangle void drm_rect_downscale struct drm_rect * r int horz int vert r rectangle to be downscaled horz horizontal downscale factor vert vertical downscale factor Divide the coordinates of rectangle r by horz and vert. Kernel Hackers Manual July 2017 drm_rect_width 9 4.1.27 drm_rect_width determine the rectangle width int drm_rect_width const struct drm_rect * r r rectangle whose width is returned The width of the rectangle. Kernel Hackers Manual July 2017 drm_rect_height 9 4.1.27 drm_rect_height determine the rectangle height int drm_rect_height const struct drm_rect * r r rectangle whose height is returned The height of the rectangle. Kernel Hackers Manual July 2017 drm_rect_visible 9 4.1.27 drm_rect_visible determine if the the rectangle is visible bool drm_rect_visible const struct drm_rect * r r rectangle whose visibility is returned true if the rectangle is visible, false otherwise. Kernel Hackers Manual July 2017 drm_rect_equals 9 4.1.27 drm_rect_equals determine if two rectangles are equal bool drm_rect_equals const struct drm_rect * r1 const struct drm_rect * r2 r1 first rectangle r2 second rectangle true if the rectangles are equal, false otherwise. Kernel Hackers Manual July 2017 drm_rect_intersect 9 4.1.27 drm_rect_intersect intersect two rectangles bool drm_rect_intersect struct drm_rect * r1 const struct drm_rect * r2 r1 first rectangle r2 second rectangle Calculate the intersection of rectangles r1 and r2. r1 will be overwritten with the intersection. true if rectangle r1 is still visible after the operation, false otherwise. Kernel Hackers Manual July 2017 drm_rect_clip_scaled 9 4.1.27 drm_rect_clip_scaled perform a scaled clip operation bool drm_rect_clip_scaled struct drm_rect * src struct drm_rect * dst const struct drm_rect * clip int hscale int vscale src source window rectangle dst destination window rectangle clip clip rectangle hscale horizontal scaling factor vscale vertical scaling factor Clip rectangle dst by rectangle clip. Clip rectangle src by the same amounts multiplied by hscale and vscale. true if rectangle dst is still visible after being clipped, false otherwise Kernel Hackers Manual July 2017 drm_rect_calc_hscale 9 4.1.27 drm_rect_calc_hscale calculate the horizontal scaling factor int drm_rect_calc_hscale const struct drm_rect * src const struct drm_rect * dst int min_hscale int max_hscale src source window rectangle dst destination window rectangle min_hscale minimum allowed horizontal scaling factor max_hscale maximum allowed horizontal scaling factor Calculate the horizontal scaling factor as (src width) / (dst width). The horizontal scaling factor, or errno of out of limits. Kernel Hackers Manual July 2017 drm_rect_calc_vscale 9 4.1.27 drm_rect_calc_vscale calculate the vertical scaling factor int drm_rect_calc_vscale const struct drm_rect * src const struct drm_rect * dst int min_vscale int max_vscale src source window rectangle dst destination window rectangle min_vscale minimum allowed vertical scaling factor max_vscale maximum allowed vertical scaling factor Calculate the vertical scaling factor as (src height) / (dst height). The vertical scaling factor, or errno of out of limits. Kernel Hackers Manual July 2017 drm_rect_calc_hscale_relaxed 9 4.1.27 drm_rect_calc_hscale_relaxed calculate the horizontal scaling factor int drm_rect_calc_hscale_relaxed struct drm_rect * src struct drm_rect * dst int min_hscale int max_hscale src source window rectangle dst destination window rectangle min_hscale minimum allowed horizontal scaling factor max_hscale maximum allowed horizontal scaling factor Calculate the horizontal scaling factor as (src width) / (dst width). If the calculated scaling factor is below min_vscale, decrease the height of rectangle dst to compensate. If the calculated scaling factor is above max_vscale, decrease the height of rectangle src to compensate. The horizontal scaling factor. Kernel Hackers Manual July 2017 drm_rect_calc_vscale_relaxed 9 4.1.27 drm_rect_calc_vscale_relaxed calculate the vertical scaling factor int drm_rect_calc_vscale_relaxed struct drm_rect * src struct drm_rect * dst int min_vscale int max_vscale src source window rectangle dst destination window rectangle min_vscale minimum allowed vertical scaling factor max_vscale maximum allowed vertical scaling factor Calculate the vertical scaling factor as (src height) / (dst height). If the calculated scaling factor is below min_vscale, decrease the height of rectangle dst to compensate. If the calculated scaling factor is above max_vscale, decrease the height of rectangle src to compensate. The vertical scaling factor. Kernel Hackers Manual July 2017 drm_rect_debug_print 9 4.1.27 drm_rect_debug_print print the rectangle information void drm_rect_debug_print const struct drm_rect * r bool fixed_point r rectangle to print fixed_point rectangle is in 16.16 fixed point format Kernel Hackers Manual July 2017 drm_rect_rotate 9 4.1.27 drm_rect_rotate Rotate the rectangle void drm_rect_rotate struct drm_rect * r int width int height unsigned int rotation r rectangle to be rotated width Width of the coordinate space height Height of the coordinate space rotation Transformation to be applied Apply rotation to the coordinates of rectangle r. width and height combined with rotation define the location of the new origin. width correcsponds to the horizontal and height to the vertical axis of the untransformed coordinate space. Kernel Hackers Manual July 2017 drm_rect_rotate_inv 9 4.1.27 drm_rect_rotate_inv Inverse rotate the rectangle void drm_rect_rotate_inv struct drm_rect * r int width int height unsigned int rotation r rectangle to be rotated width Width of the coordinate space height Height of the coordinate space rotation Transformation whose inverse is to be applied Apply the inverse of rotation to the coordinates of rectangle r. width and height combined with rotation define the location of the new origin. width correcsponds to the horizontal and height to the vertical axis of the original untransformed coordinate space, so that you never have to flip them when doing a rotatation and its inverse. That is, if you do: drm_rotate(r, width, height, rotation); drm_rotate_inv(r, width, height, rotation); you will always get back the original rectangle. Util to queue up work to run from work-queue context after flip/vblank. Typically this can be used to defer unref of framebuffer's, cursor bo's, etc until after vblank. The APIs are all thread-safe. Moreover, drm_flip_work_queue_task and drm_flip_work_queue can be called in atomic context. Kernel Hackers Manual July 2017 struct drm_flip_task 9 4.1.27 struct drm_flip_task flip work task struct drm_flip_task { struct list_head node; void * data; }; node list entry element data data to pass to work->func Kernel Hackers Manual July 2017 struct drm_flip_work 9 4.1.27 struct drm_flip_work flip work queue struct drm_flip_work { const char * name; drm_flip_func_t func; struct work_struct worker; struct list_head queued; struct list_head commited; spinlock_t lock; }; name debug name func callback fxn called for each committed item worker worker which calls func queued queued tasks commited commited tasks lock lock to access queued and commited lists Kernel Hackers Manual July 2017 drm_flip_work_allocate_task 9 4.1.27 drm_flip_work_allocate_task allocate a flip-work task struct drm_flip_task * drm_flip_work_allocate_task void * data gfp_t flags data data associated to the task flags allocator flags Allocate a drm_flip_task object and attach private data to it. Kernel Hackers Manual July 2017 drm_flip_work_queue_task 9 4.1.27 drm_flip_work_queue_task queue a specific task void drm_flip_work_queue_task struct drm_flip_work * work struct drm_flip_task * task work the flip-work task the task to handle Queues task, that will later be run (passed back to drm_flip_func_t func) on a work queue after drm_flip_work_commit is called. Kernel Hackers Manual July 2017 drm_flip_work_queue 9 4.1.27 drm_flip_work_queue queue work void drm_flip_work_queue struct drm_flip_work * work void * val work the flip-work val the value to queue Queues work, that will later be run (passed back to drm_flip_func_t func) on a work queue after drm_flip_work_commit is called. Kernel Hackers Manual July 2017 drm_flip_work_commit 9 4.1.27 drm_flip_work_commit commit queued work void drm_flip_work_commit struct drm_flip_work * work struct workqueue_struct * wq work the flip-work wq the work-queue to run the queued work on Trigger work previously queued by drm_flip_work_queue to run on a workqueue. The typical usage would be to queue work (via drm_flip_work_queue) at any point (from vblank irq and/or prior), and then from vblank irq commit the queued work. Kernel Hackers Manual July 2017 drm_flip_work_init 9 4.1.27 drm_flip_work_init initialize flip-work void drm_flip_work_init struct drm_flip_work * work const char * name drm_flip_func_t func work the flip-work to initialize name debug name func the callback work function Initializes/allocates resources for the flip-work Kernel Hackers Manual July 2017 drm_flip_work_cleanup 9 4.1.27 drm_flip_work_cleanup cleans up flip-work void drm_flip_work_cleanup struct drm_flip_work * work work the flip-work to cleanup Destroy resources allocated for the flip-work Strictly speaking this is not a DRM helper library but generally useable by any driver interfacing with HDMI outputs like v4l or alsa drivers. But it nicely fits into the overall topic of mode setting helper libraries and hence is also included here. Kernel Hackers Manual July 2017 union hdmi_infoframe 9 4.1.27 union hdmi_infoframe overall union of all abstract infoframe representations union hdmi_infoframe { struct hdmi_any_infoframe any; struct hdmi_avi_infoframe avi; struct hdmi_spd_infoframe spd; union hdmi_vendor_any_infoframe vendor; struct hdmi_audio_infoframe audio; }; any generic infoframe avi avi infoframe spd spd infoframe vendor union of all vendor infoframes audio audio infoframe This is used by the generic pack function. This works since all infoframes have the same header which also indicates which type of infoframe should be packed. Kernel Hackers Manual July 2017 hdmi_avi_infoframe_init 9 4.1.27 hdmi_avi_infoframe_init initialize an HDMI AVI infoframe int hdmi_avi_infoframe_init struct hdmi_avi_infoframe * frame frame HDMI AVI infoframe Returns 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 hdmi_avi_infoframe_pack 9 4.1.27 hdmi_avi_infoframe_pack write HDMI AVI infoframe to binary buffer ssize_t hdmi_avi_infoframe_pack struct hdmi_avi_infoframe * frame void * buffer size_t size frame HDMI AVI infoframe buffer destination buffer size size of buffer Packs the information contained in the frame structure into a binary representation that can be written into the corresponding controller registers. Also computes the checksum as required by section 5.3.5 of the HDMI 1.4 specification. Returns the number of bytes packed into the binary buffer or a negative error code on failure. Kernel Hackers Manual July 2017 hdmi_spd_infoframe_init 9 4.1.27 hdmi_spd_infoframe_init initialize an HDMI SPD infoframe int hdmi_spd_infoframe_init struct hdmi_spd_infoframe * frame const char * vendor const char * product frame HDMI SPD infoframe vendor vendor string product product string Returns 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 hdmi_spd_infoframe_pack 9 4.1.27 hdmi_spd_infoframe_pack write HDMI SPD infoframe to binary buffer ssize_t hdmi_spd_infoframe_pack struct hdmi_spd_infoframe * frame void * buffer size_t size frame HDMI SPD infoframe buffer destination buffer size size of buffer Packs the information contained in the frame structure into a binary representation that can be written into the corresponding controller registers. Also computes the checksum as required by section 5.3.5 of the HDMI 1.4 specification. Returns the number of bytes packed into the binary buffer or a negative error code on failure. Kernel Hackers Manual July 2017 hdmi_audio_infoframe_init 9 4.1.27 hdmi_audio_infoframe_init initialize an HDMI audio infoframe int hdmi_audio_infoframe_init struct hdmi_audio_infoframe * frame frame HDMI audio infoframe Returns 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 hdmi_audio_infoframe_pack 9 4.1.27 hdmi_audio_infoframe_pack write HDMI audio infoframe to binary buffer ssize_t hdmi_audio_infoframe_pack struct hdmi_audio_infoframe * frame void * buffer size_t size frame HDMI audio infoframe buffer destination buffer size size of buffer Packs the information contained in the frame structure into a binary representation that can be written into the corresponding controller registers. Also computes the checksum as required by section 5.3.5 of the HDMI 1.4 specification. Returns the number of bytes packed into the binary buffer or a negative error code on failure. Kernel Hackers Manual July 2017 hdmi_vendor_infoframe_init 9 4.1.27 hdmi_vendor_infoframe_init initialize an HDMI vendor infoframe int hdmi_vendor_infoframe_init struct hdmi_vendor_infoframe * frame frame HDMI vendor infoframe Returns 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 hdmi_vendor_infoframe_pack 9 4.1.27 hdmi_vendor_infoframe_pack write a HDMI vendor infoframe to binary buffer ssize_t hdmi_vendor_infoframe_pack struct hdmi_vendor_infoframe * frame void * buffer size_t size frame HDMI infoframe buffer destination buffer size size of buffer Packs the information contained in the frame structure into a binary representation that can be written into the corresponding controller registers. Also computes the checksum as required by section 5.3.5 of the HDMI 1.4 specification. Returns the number of bytes packed into the binary buffer or a negative error code on failure. Kernel Hackers Manual July 2017 hdmi_infoframe_pack 9 4.1.27 hdmi_infoframe_pack write a HDMI infoframe to binary buffer ssize_t hdmi_infoframe_pack union hdmi_infoframe * frame void * buffer size_t size frame HDMI infoframe buffer destination buffer size size of buffer Packs the information contained in the frame structure into a binary representation that can be written into the corresponding controller registers. Also computes the checksum as required by section 5.3.5 of the HDMI 1.4 specification. Returns the number of bytes packed into the binary buffer or a negative error code on failure. Kernel Hackers Manual July 2017 hdmi_infoframe_log 9 4.1.27 hdmi_infoframe_log log info of HDMI infoframe void hdmi_infoframe_log const char * level struct device * dev union hdmi_infoframe * frame level logging level dev device frame HDMI infoframe Kernel Hackers Manual July 2017 hdmi_infoframe_unpack 9 4.1.27 hdmi_infoframe_unpack unpack binary buffer to a HDMI infoframe int hdmi_infoframe_unpack union hdmi_infoframe * frame void * buffer frame HDMI infoframe buffer source buffer Unpacks the information contained in binary buffer buffer into a structured frame of a HDMI infoframe. Also verifies the checksum as required by section 5.3.5 of the HDMI 1.4 specification. Returns 0 on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_plane_helper_check_update 9 4.1.27 drm_plane_helper_check_update Check plane update for validity int drm_plane_helper_check_update struct drm_plane * plane struct drm_crtc * crtc struct drm_framebuffer * fb struct drm_rect * src struct drm_rect * dest const struct drm_rect * clip int min_scale int max_scale bool can_position bool can_update_disabled bool * visible plane plane object to update crtc owning CRTC of owning plane fb framebuffer to flip onto plane src source coordinates in 16.16 fixed point dest integer destination coordinates clip integer clipping coordinates min_scale minimum src:dest scaling factor in 16.16 fixed point max_scale maximum src:dest scaling factor in 16.16 fixed point can_position is it legal to position the plane such that it doesn't cover the entire crtc? This will generally only be false for primary planes. can_update_disabled can the plane be updated while the crtc is disabled? visible output parameter indicating whether plane is still visible after clipping Checks that a desired plane update is valid. Drivers that provide their own plane handling rather than helper-provided implementations may still wish to call this function to avoid duplication of error checking code. Zero if update appears valid, error code on failure Kernel Hackers Manual July 2017 drm_primary_helper_update 9 4.1.27 drm_primary_helper_update Helper for primary plane update int drm_primary_helper_update struct drm_plane * plane struct drm_crtc * crtc struct drm_framebuffer * fb int crtc_x int crtc_y unsigned int crtc_w unsigned int crtc_h uint32_t src_x uint32_t src_y uint32_t src_w uint32_t src_h plane plane object to update crtc owning CRTC of owning plane fb framebuffer to flip onto plane crtc_x x offset of primary plane on crtc crtc_y y offset of primary plane on crtc crtc_w width of primary plane rectangle on crtc crtc_h height of primary plane rectangle on crtc src_x x offset of fb for panning src_y y offset of fb for panning src_w width of source rectangle in fb src_h height of source rectangle in fb Provides a default plane update handler for primary planes. This is handler is called in response to a userspace SetPlane operation on the plane with a non-NULL framebuffer. We call the driver's modeset handler to update the framebuffer. SetPlane on a primary plane of a disabled CRTC is not supported, and will return an error. Note that we make some assumptions about hardware limitations that may not be true for all hardware -- 1) Primary plane cannot be repositioned. 2) Primary plane cannot be scaled. 3) Primary plane must cover the entire CRTC. 4) Subpixel positioning is not supported. Drivers for hardware that don't have these restrictions can provide their own implementation rather than using this helper. Zero on success, error code on failure Kernel Hackers Manual July 2017 drm_primary_helper_disable 9 4.1.27 drm_primary_helper_disable Helper for primary plane disable int drm_primary_helper_disable struct drm_plane * plane plane plane to disable Provides a default plane disable handler for primary planes. This is handler is called in response to a userspace SetPlane operation on the plane with a NULL framebuffer parameter. It unconditionally fails the disable call with -EINVAL the only way to disable the primary plane without driver support is to disable the entier CRTC. Which does not match the plane ->disable hook. Note that some hardware may be able to disable the primary plane without disabling the whole CRTC. Drivers for such hardware should provide their own disable handler that disables just the primary plane (and they'll likely need to provide their own update handler as well to properly re-enable a disabled primary plane). Unconditionally returns -EINVAL. Kernel Hackers Manual July 2017 drm_primary_helper_destroy 9 4.1.27 drm_primary_helper_destroy Helper for primary plane destruction void drm_primary_helper_destroy struct drm_plane * plane plane plane to destroy Provides a default plane destroy handler for primary planes. This handler is called during CRTC destruction. We disable the primary plane, remove it from the DRM plane list, and deallocate the plane structure. Kernel Hackers Manual July 2017 drm_crtc_init 9 4.1.27 drm_crtc_init Legacy CRTC initialization function int drm_crtc_init struct drm_device * dev struct drm_crtc * crtc const struct drm_crtc_funcs * funcs dev DRM device crtc CRTC object to init funcs callbacks for the new CRTC Initialize a CRTC object with a default helper-provided primary plane and no cursor plane. Zero on success, error code on failure. Kernel Hackers Manual July 2017 drm_plane_helper_update 9 4.1.27 drm_plane_helper_update Transitional helper for plane update int drm_plane_helper_update struct drm_plane * plane struct drm_crtc * crtc struct drm_framebuffer * fb int crtc_x int crtc_y unsigned int crtc_w unsigned int crtc_h uint32_t src_x uint32_t src_y uint32_t src_w uint32_t src_h plane plane object to update crtc owning CRTC of owning plane fb framebuffer to flip onto plane crtc_x x offset of primary plane on crtc crtc_y y offset of primary plane on crtc crtc_w width of primary plane rectangle on crtc crtc_h height of primary plane rectangle on crtc src_x x offset of fb for panning src_y y offset of fb for panning src_w width of source rectangle in fb src_h height of source rectangle in fb Provides a default plane update handler using the atomic plane update functions. It is fully left to the driver to check plane constraints and handle corner-cases like a fully occluded or otherwise invisible plane. This is useful for piecewise transitioning of a driver to the atomic helpers. Zero on success, error code on failure Kernel Hackers Manual July 2017 drm_plane_helper_disable 9 4.1.27 drm_plane_helper_disable Transitional helper for plane disable int drm_plane_helper_disable struct drm_plane * plane plane plane to disable Provides a default plane disable handler using the atomic plane update functions. It is fully left to the driver to check plane constraints and handle corner-cases like a fully occluded or otherwise invisible plane. This is useful for piecewise transitioning of a driver to the atomic helpers. Zero on success, error code on failure This helper library has two parts. The first part has support to implement primary plane support on top of the normal CRTC configuration interface. Since the legacy ->set_config interface ties the primary plane together with the CRTC state this does not allow userspace to disable the primary plane itself. To avoid too much duplicated code use drm_plane_helper_check_update which can be used to enforce the same restrictions as primary planes had thus. The default primary plane only expose XRBG8888 and ARGB8888 as valid pixel formats for the attached framebuffer. Drivers are highly recommended to implement proper support for primary planes, and newly merged drivers must not rely upon these transitional helpers. The second part also implements transitional helpers which allow drivers to gradually switch to the atomic helper infrastructure for plane updates. Once that switch is complete drivers shouldn't use these any longer, instead using the proper legacy implementations for update and disable plane hooks provided by the atomic helpers. Again drivers are strongly urged to switch to the new interfaces. Tile groups are used to represent tiled monitors with a unique integer identifier. Tiled monitors using DisplayID v1.3 have a unique 8-byte handle, we store this in a tile group, so we have a common identifier for all tiles in a monitor group. Drivers may need to expose additional parameters to applications than those described in the previous sections. KMS supports attaching properties to CRTCs, connectors and planes and offers a userspace API to list, get and set the property values. Properties are identified by a name that uniquely defines the property purpose, and store an associated value. For all property types except blob properties the value is a 64-bit unsigned integer. KMS differentiates between properties and property instances. Drivers first create properties and then create and associate individual instances of those properties to objects. A property can be instantiated multiple times and associated with different objects. Values are stored in property instances, and all other property information are stored in the property and shared between all instances of the property. Every property is created with a type that influences how the KMS core handles the property. Supported property types are DRM_MODE_PROP_RANGE Range properties report their minimum and maximum admissible values. The KMS core verifies that values set by application fit in that range. DRM_MODE_PROP_ENUM Enumerated properties take a numerical value that ranges from 0 to the number of enumerated values defined by the property minus one, and associate a free-formed string name to each value. Applications can retrieve the list of defined value-name pairs and use the numerical value to get and set property instance values. DRM_MODE_PROP_BITMASK Bitmask properties are enumeration properties that additionally restrict all enumerated values to the 0..63 range. Bitmask property instance values combine one or more of the enumerated bits defined by the property. DRM_MODE_PROP_BLOB Blob properties store a binary blob without any format restriction. The binary blobs are created as KMS standalone objects, and blob property instance values store the ID of their associated blob object. Blob properties are only used for the connector EDID property and cannot be created by drivers. To create a property drivers call one of the following functions depending on the property type. All property creation functions take property flags and name, as well as type-specific arguments. struct drm_property *drm_property_create_range(struct drm_device *dev, int flags, const char *name, uint64_t min, uint64_t max); Create a range property with the given minimum and maximum values. struct drm_property *drm_property_create_enum(struct drm_device *dev, int flags, const char *name, const struct drm_prop_enum_list *props, int num_values); Create an enumerated property. The props argument points to an array of num_values value-name pairs. struct drm_property *drm_property_create_bitmask(struct drm_device *dev, int flags, const char *name, const struct drm_prop_enum_list *props, int num_values); Create a bitmask property. The props argument points to an array of num_values value-name pairs. Properties can additionally be created as immutable, in which case they will be read-only for applications but can be modified by the driver. To create an immutable property drivers must set the DRM_MODE_PROP_IMMUTABLE flag at property creation time. When no array of value-name pairs is readily available at property creation time for enumerated or range properties, drivers can create the property using the drm_property_create function and manually add enumeration value-name pairs by calling the drm_property_add_enum function. Care must be taken to properly specify the property type through the flags argument. After creating properties drivers can attach property instances to CRTC, connector and plane objects by calling the drm_object_attach_property. The function takes a pointer to the target object, a pointer to the previously created property and an initial instance value. The following table gives description of drm properties exposed by various modules/drivers.

Owner Module/Drivers	Group	Property Name	Type	Property Values	Object attached	Description/Restrictions
DRM	Connector	“EDID”	BLOB | IMMUTABLE	0	Connector	Contains id of edid blob ptr object.
		“DPMS”	ENUM	{ “On”, “Standby”, “Suspend”, “Off” }	Connector	Contains DPMS operation mode value.
		“PATH”	BLOB | IMMUTABLE	0	Connector	Contains topology path to a connector.
		“TILE”	BLOB | IMMUTABLE	0	Connector	Contains tiling information for a connector.
		“CRTC_ID”	OBJECT	DRM_MODE_OBJECT_CRTC	Connector	CRTC that connector is attached to (atomic)
	Plane	“type”	ENUM | IMMUTABLE	{ "Overlay", "Primary", "Cursor" }	Plane	Plane type
		“SRC_X”	RANGE	Min=0, Max=UINT_MAX	Plane	Scanout source x coordinate in 16.16 fixed point (atomic)
		“SRC_Y”	RANGE	Min=0, Max=UINT_MAX	Plane	Scanout source y coordinate in 16.16 fixed point (atomic)
		“SRC_W”	RANGE	Min=0, Max=UINT_MAX	Plane	Scanout source width in 16.16 fixed point (atomic)
		“SRC_H”	RANGE	Min=0, Max=UINT_MAX	Plane	Scanout source height in 16.16 fixed point (atomic)
		“CRTC_X”	SIGNED_RANGE	Min=INT_MIN, Max=INT_MAX	Plane	Scanout CRTC (destination) x coordinate (atomic)
		“CRTC_Y”	SIGNED_RANGE	Min=INT_MIN, Max=INT_MAX	Plane	Scanout CRTC (destination) y coordinate (atomic)
		“CRTC_W”	RANGE	Min=0, Max=UINT_MAX	Plane	Scanout CRTC (destination) width (atomic)
		“CRTC_H”	RANGE	Min=0, Max=UINT_MAX	Plane	Scanout CRTC (destination) height (atomic)
		“FB_ID”	OBJECT	DRM_MODE_OBJECT_FB	Plane	Scanout framebuffer (atomic)
		“CRTC_ID”	OBJECT	DRM_MODE_OBJECT_CRTC	Plane	CRTC that plane is attached to (atomic)
	DVI-I	“subconnector”	ENUM	{ “Unknown”, “DVI-D”, “DVI-A” }	Connector	TBD
		“select subconnector”	ENUM	{ “Automatic”, “DVI-D”, “DVI-A” }	Connector	TBD
	TV	“subconnector”	ENUM	{ "Unknown", "Composite", "SVIDEO", "Component", "SCART" }	Connector	TBD
		“select subconnector”	ENUM	{ "Automatic", "Composite", "SVIDEO", "Component", "SCART" }	Connector	TBD
		“mode”	ENUM	{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.	Connector	TBD
		“left margin”	RANGE	Min=0, Max=100	Connector	TBD
		“right margin”	RANGE	Min=0, Max=100	Connector	TBD
		“top margin”	RANGE	Min=0, Max=100	Connector	TBD
		“bottom margin”	RANGE	Min=0, Max=100	Connector	TBD
		“brightness”	RANGE	Min=0, Max=100	Connector	TBD
		“contrast”	RANGE	Min=0, Max=100	Connector	TBD
		“flicker reduction”	RANGE	Min=0, Max=100	Connector	TBD
		“overscan”	RANGE	Min=0, Max=100	Connector	TBD
		“saturation”	RANGE	Min=0, Max=100	Connector	TBD
		“hue”	RANGE	Min=0, Max=100	Connector	TBD
	Virtual GPU	“suggested X”	RANGE	Min=0, Max=0xffffffff	Connector	property to suggest an X offset for a connector
		“suggested Y”	RANGE	Min=0, Max=0xffffffff	Connector	property to suggest an Y offset for a connector
	Optional	“scaling mode”	ENUM	{ "None", "Full", "Center", "Full aspect" }	Connector	TBD
		"aspect ratio"	ENUM	{ "None", "4:3", "16:9" }	Connector	DRM property to set aspect ratio from user space app. This enum is made generic to allow addition of custom aspect ratios.
		“dirty”	ENUM | IMMUTABLE	{ "Off", "On", "Annotate" }	Connector	TBD
i915	Generic	"Broadcast RGB"	ENUM	{ "Automatic", "Full", "Limited 16:235" }	Connector	TBD
		“audio”	ENUM	{ "force-dvi", "off", "auto", "on" }	Connector	TBD
	Plane	“rotation”	BITMASK	{ 0, "rotate-0" }, { 2, "rotate-180" }	Plane	TBD
	SDVO-TV	“mode”	ENUM	{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.	Connector	TBD
		"left_margin"	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		"right_margin"	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		"top_margin"	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		"bottom_margin"	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“hpos”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“vpos”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“contrast”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“saturation”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“hue”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“sharpness”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“flicker_filter”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“flicker_filter_adaptive”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“flicker_filter_2d”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“tv_chroma_filter”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“tv_luma_filter”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“dot_crawl”	RANGE	Min=0, Max=1	Connector	TBD
	SDVO-TV/LVDS	“brightness”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
CDV gma-500	Generic	"Broadcast RGB"	ENUM	{ “Full”, “Limited 16:235” }	Connector	TBD
		"Broadcast RGB"	ENUM	{ “off”, “auto”, “on” }	Connector	TBD
Poulsbo	Generic	“backlight”	RANGE	Min=0, Max=100	Connector	TBD
	SDVO-TV	“mode”	ENUM	{ "NTSC_M", "NTSC_J", "NTSC_443", "PAL_B" } etc.	Connector	TBD
		"left_margin"	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		"right_margin"	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		"top_margin"	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		"bottom_margin"	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“hpos”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“vpos”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“contrast”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“saturation”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“hue”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“sharpness”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“flicker_filter”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“flicker_filter_adaptive”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“flicker_filter_2d”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“tv_chroma_filter”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“tv_luma_filter”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
		“dot_crawl”	RANGE	Min=0, Max=1	Connector	TBD
	SDVO-TV/LVDS	“brightness”	RANGE	Min=0, Max= SDVO dependent	Connector	TBD
armada	CRTC	"CSC_YUV"	ENUM	{ "Auto" , "CCIR601", "CCIR709" }	CRTC	TBD
		"CSC_RGB"	ENUM	{ "Auto", "Computer system", "Studio" }	CRTC	TBD
	Overlay	"colorkey"	RANGE	Min=0, Max=0xffffff	Plane	TBD
		"colorkey_min"	RANGE	Min=0, Max=0xffffff	Plane	TBD
		"colorkey_max"	RANGE	Min=0, Max=0xffffff	Plane	TBD
		"colorkey_val"	RANGE	Min=0, Max=0xffffff	Plane	TBD
		"colorkey_alpha"	RANGE	Min=0, Max=0xffffff	Plane	TBD
		"colorkey_mode"	ENUM	{ "disabled", "Y component", "U component" , "V component", "RGB", “R component", "G component", "B component" }	Plane	TBD
		"brightness"	RANGE	Min=0, Max=256 + 255	Plane	TBD
		"contrast"	RANGE	Min=0, Max=0x7fff	Plane	TBD
		"saturation"	RANGE	Min=0, Max=0x7fff	Plane	TBD
exynos	CRTC	“mode”	ENUM	{ "normal", "blank" }	CRTC	TBD
	Overlay	“zpos”	RANGE	Min=0, Max=MAX_PLANE-1	Plane	TBD
i2c/ch7006_drv	Generic	“scale”	RANGE	Min=0, Max=2	Connector	TBD
	TV	“mode”	ENUM	{ "PAL", "PAL-M","PAL-N"}, ”PAL-Nc" , "PAL-60", "NTSC-M", "NTSC-J" }	Connector	TBD
nouveau	NV10 Overlay	"colorkey"	RANGE	Min=0, Max=0x01ffffff	Plane	TBD
		“contrast”	RANGE	Min=0, Max=8192-1	Plane	TBD
		“brightness”	RANGE	Min=0, Max=1024	Plane	TBD
		“hue”	RANGE	Min=0, Max=359	Plane	TBD
		“saturation”	RANGE	Min=0, Max=8192-1	Plane	TBD
		“iturbt_709”	RANGE	Min=0, Max=1	Plane	TBD
	Nv04 Overlay	“colorkey”	RANGE	Min=0, Max=0x01ffffff	Plane	TBD
		“brightness”	RANGE	Min=0, Max=1024	Plane	TBD
	Display	“dithering mode”	ENUM	{ "auto", "off", "on" }	Connector	TBD
		“dithering depth”	ENUM	{ "auto", "off", "on", "static 2x2", "dynamic 2x2", "temporal" }	Connector	TBD
		“underscan”	ENUM	{ "auto", "6 bpc", "8 bpc" }	Connector	TBD
		“underscan hborder”	RANGE	Min=0, Max=128	Connector	TBD
		“underscan vborder”	RANGE	Min=0, Max=128	Connector	TBD
		“vibrant hue”	RANGE	Min=0, Max=180	Connector	TBD
		“color vibrance”	RANGE	Min=0, Max=200	Connector	TBD
omap	Generic	“rotation”	BITMASK	{ 0, "rotate-0" }, { 1, "rotate-90" }, { 2, "rotate-180" }, { 3, "rotate-270" }, { 4, "reflect-x" }, { 5, "reflect-y" }	CRTC, Plane	TBD
		“zorder”	RANGE	Min=0, Max=3	CRTC, Plane	TBD
qxl	Generic	“hotplug_mode_update"	RANGE	Min=0, Max=1	Connector	TBD
radeon	DVI-I	“coherent”	RANGE	Min=0, Max=1	Connector	TBD
	DAC enable load detect	“load detection”	RANGE	Min=0, Max=1	Connector	TBD
	TV Standard	"tv standard"	ENUM	{ "ntsc", "pal", "pal-m", "pal-60", "ntsc-j" , "scart-pal", "pal-cn", "secam" }	Connector	TBD
	legacy TMDS PLL detect	"tmds_pll"	ENUM	{ "driver", "bios" }	-	TBD
	Underscan	"underscan"	ENUM	{ "off", "on", "auto" }	Connector	TBD
		"underscan hborder"	RANGE	Min=0, Max=128	Connector	TBD
		"underscan vborder"	RANGE	Min=0, Max=128	Connector	TBD
	Audio	“audio”	ENUM	{ "off", "on", "auto" }	Connector	TBD
	FMT Dithering	“dither”	ENUM	{ "off", "on" }	Connector	TBD
rcar-du	Generic	"alpha"	RANGE	Min=0, Max=255	Plane	TBD
		"colorkey"	RANGE	Min=0, Max=0x01ffffff	Plane	TBD
		"zpos"	RANGE	Min=1, Max=7	Plane	TBD

Vertical blanking plays a major role in graphics rendering. To achieve tear-free display, users must synchronize page flips and/or rendering to vertical blanking. The DRM API offers ioctls to perform page flips synchronized to vertical blanking and wait for vertical blanking. The DRM core handles most of the vertical blanking management logic, which involves filtering out spurious interrupts, keeping race-free blanking counters, coping with counter wrap-around and resets and keeping use counts. It relies on the driver to generate vertical blanking interrupts and optionally provide a hardware vertical blanking counter. Drivers must implement the following operations. int (*enable_vblank) (struct drm_device *dev, int crtc); void (*disable_vblank) (struct drm_device *dev, int crtc); Enable or disable vertical blanking interrupts for the given CRTC. u32 (*get_vblank_counter) (struct drm_device *dev, int crtc); Retrieve the value of the vertical blanking counter for the given CRTC. If the hardware maintains a vertical blanking counter its value should be returned. Otherwise drivers can use the drm_vblank_count helper function to handle this operation. Drivers must initialize the vertical blanking handling core with a call to drm_vblank_init in their load operation. The function will set the struct drm_device vblank_disable_allowed field to 0. This will keep vertical blanking interrupts enabled permanently until the first mode set operation, where vblank_disable_allowed is set to 1. The reason behind this is not clear. Drivers can set the field to 1 after calling drm_vblank_init to make vertical blanking interrupts dynamically managed from the beginning. Vertical blanking interrupts can be enabled by the DRM core or by drivers themselves (for instance to handle page flipping operations). The DRM core maintains a vertical blanking use count to ensure that the interrupts are not disabled while a user still needs them. To increment the use count, drivers call drm_vblank_get. Upon return vertical blanking interrupts are guaranteed to be enabled. To decrement the use count drivers call drm_vblank_put. Only when the use count drops to zero will the DRM core disable the vertical blanking interrupts after a delay by scheduling a timer. The delay is accessible through the vblankoffdelay module parameter or the drm_vblank_offdelay global variable and expressed in milliseconds. Its default value is 5000 ms. Zero means never disable, and a negative value means disable immediately. Drivers may override the behaviour by setting the drm_device vblank_disable_immediate flag, which when set causes vblank interrupts to be disabled immediately regardless of the drm_vblank_offdelay value. The flag should only be set if there's a properly working hardware vblank counter present. When a vertical blanking interrupt occurs drivers only need to call the drm_handle_vblank function to account for the interrupt. Resources allocated by drm_vblank_init must be freed with a call to drm_vblank_cleanup in the driver unload operation handler. Kernel Hackers Manual July 2017 drm_vblank_cleanup 9 4.1.27 drm_vblank_cleanup cleanup vblank support void drm_vblank_cleanup struct drm_device * dev dev DRM device This function cleans up any resources allocated in drm_vblank_init. Kernel Hackers Manual July 2017 drm_vblank_init 9 4.1.27 drm_vblank_init initialize vblank support int drm_vblank_init struct drm_device * dev int num_crtcs dev drm_device num_crtcs number of crtcs supported by dev This function initializes vblank support for num_crtcs display pipelines. Zero on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_irq_install 9 4.1.27 drm_irq_install install IRQ handler int drm_irq_install struct drm_device * dev int irq dev DRM device irq IRQ number to install the handler for Initializes the IRQ related data. Installs the handler, calling the driver irq_preinstall and irq_postinstall functions before and after the installation. This is the simplified helper interface provided for drivers with no special needs. Drivers which need to install interrupt handlers for multiple interrupts must instead set drm_device->irq_enabled to signal the DRM core that vblank interrupts are available. Zero on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_irq_uninstall 9 4.1.27 drm_irq_uninstall uninstall the IRQ handler int drm_irq_uninstall struct drm_device * dev dev DRM device Calls the driver's irq_uninstall function and unregisters the IRQ handler. This should only be called by drivers which used drm_irq_install to set up their interrupt handler. Other drivers must only reset drm_device->irq_enabled to false. Note that for kernel modesetting drivers it is a bug if this function fails. The sanity checks are only to catch buggy user modesetting drivers which call the same function through an ioctl. Zero on success or a negative error code on failure. Kernel Hackers Manual July 2017 drm_calc_timestamping_constants 9 4.1.27 drm_calc_timestamping_constants calculate vblank timestamp constants void drm_calc_timestamping_constants struct drm_crtc * crtc const struct drm_display_mode * mode crtc drm_crtc whose timestamp constants should be updated. mode display mode containing the scanout timings Calculate and store various constants which are later needed by vblank and swap-completion timestamping, e.g, by drm_calc_vbltimestamp_from_scanoutpos. They are derived from CRTC's true scanout timing, so they take things like panel scaling or other adjustments into account. Kernel Hackers Manual July 2017 drm_calc_vbltimestamp_from_scanoutpos 9 4.1.27 drm_calc_vbltimestamp_from_scanoutpos precise vblank timestamp helper int drm_calc_vbltimestamp_from_scanoutpos struct drm_device * dev int crtc int * max_error struct timeval * vblank_time unsigned flags const struct drm_crtc * refcrtc const struct drm_display_mode * mode dev DRM device crtc Which CRTC's vblank timestamp to retrieve max_error Desired maximum allowable error in timestamps (nanosecs) On return contains true maximum error of timestamp vblank_time Pointer to struct timeval which should receive the timestamp flags Flags to pass to driver: 0 = Default, DRM_CALLED_FROM_VBLIRQ = If function is called from vbl IRQ handler refcrtc CRTC which defines scanout timing mode mode which defines the scanout timings Implements calculation of exact vblank timestamps from given drm_display_mode timings and current video scanout position of a CRTC. This can be called from within get_vblank_timestamp implementation of a kms driver to implement the actual timestamping. Should return timestamps conforming to the OML_sync_control OpenML extension specification. The timestamp corresponds to the end of the vblank interval, aka start of scanout of topmost-leftmost display pixel in the following video frame. Requires support for optional dev->driver->get_scanout_position in kms driver, plus a bit of setup code to provide a drm_display_mode that corresponds to the true scanout timing. The current implementation only handles standard video modes. It returns as no operation if a doublescan or interlaced video mode is active. Higher level code is expected to handle this. Negative value on error, failure or if not supported in current -EINVAL - Invalid CRTC. -EAGAIN - Temporary unavailable, e.g., called before initial modeset. -ENOTSUPP - Function not supported in current display mode. -EIO - Failed, e.g., due to failed scanout position query. Returns or'ed positive status flags on success: DRM_VBLANKTIME_SCANOUTPOS_METHOD - Signal this method used for timestamping. DRM_VBLANKTIME_INVBL - Timestamp taken while scanout was in vblank interval. Kernel Hackers Manual July 2017 drm_vblank_count 9 4.1.27 drm_vblank_count retrieve cooked vblank counter value u32 drm_vblank_count struct drm_device * dev int crtc dev DRM device crtc which counter to retrieve Fetches the cooked vblank count value that represents the number of vblank events since the system was booted, including lost events due to modesetting activity. This is the legacy version of drm_crtc_vblank_count. The software vblank counter. Kernel Hackers Manual July 2017 drm_crtc_vblank_count 9 4.1.27 drm_crtc_vblank_count retrieve cooked vblank counter value u32 drm_crtc_vblank_count struct drm_crtc * crtc crtc which counter to retrieve Fetches the cooked vblank count value that represents the number of vblank events since the system was booted, including lost events due to modesetting activity. This is the native KMS version of drm_vblank_count. The software vblank counter. Kernel Hackers Manual July 2017 drm_vblank_count_and_time 9 4.1.27 drm_vblank_count_and_time retrieve cooked vblank counter value and the system timestamp corresponding to that vblank counter value. u32 drm_vblank_count_and_time struct drm_device * dev int crtc struct timeval * vblanktime dev DRM device crtc which counter to retrieve vblanktime Pointer to struct timeval to receive the vblank timestamp. Fetches the cooked vblank count value that represents the number of vblank events since the system was booted, including lost events due to modesetting activity. Returns corresponding system timestamp of the time of the vblank interval that corresponds to the current vblank counter value. Kernel Hackers Manual July 2017 drm_send_vblank_event 9 4.1.27 drm_send_vblank_event helper to send vblank event after pageflip void drm_send_vblank_event struct drm_device * dev int crtc struct drm_pending_vblank_event * e dev DRM device crtc CRTC in question e the event to send Updates sequence # and timestamp on event, and sends it to userspace. Caller must hold event lock. This is the legacy version of drm_crtc_send_vblank_event. Kernel Hackers Manual July 2017 drm_crtc_send_vblank_event 9 4.1.27 drm_crtc_send_vblank_event helper to send vblank event after pageflip void drm_crtc_send_vblank_event struct drm_crtc * crtc struct drm_pending_vblank_event * e crtc the source CRTC of the vblank event e the event to send Updates sequence # and timestamp on event, and sends it to userspace. Caller must hold event lock. This is the native KMS version of drm_send_vblank_event. Kernel Hackers Manual July 2017 drm_vblank_get 9 4.1.27 drm_vblank_get get a reference count on vblank events int drm_vblank_get struct drm_device * dev int crtc dev DRM device crtc which CRTC to own Acquire a reference count on vblank events to avoid having them disabled while in use. This is the legacy version of drm_crtc_vblank_get. Zero on success, nonzero on failure. Kernel Hackers Manual July 2017 drm_crtc_vblank_get 9 4.1.27 drm_crtc_vblank_get get a reference count on vblank events int drm_crtc_vblank_get struct drm_crtc * crtc crtc which CRTC to own Acquire a reference count on vblank events to avoid having them disabled while in use. This is the native kms version of drm_vblank_get. Zero on success, nonzero on failure. Kernel Hackers Manual July 2017 drm_vblank_put 9 4.1.27 drm_vblank_put give up ownership of vblank events void drm_vblank_put struct drm_device * dev int crtc dev DRM device crtc which counter to give up Release ownership of a given vblank counter, turning off interrupts if possible. Disable interrupts after drm_vblank_offdelay milliseconds. This is the legacy version of drm_crtc_vblank_put. Kernel Hackers Manual July 2017 drm_crtc_vblank_put 9 4.1.27 drm_crtc_vblank_put give up ownership of vblank events void drm_crtc_vblank_put struct drm_crtc * crtc crtc which counter to give up Release ownership of a given vblank counter, turning off interrupts if possible. Disable interrupts after drm_vblank_offdelay milliseconds. This is the native kms version of drm_vblank_put. Kernel Hackers Manual July 2017 drm_wait_one_vblank 9 4.1.27 drm_wait_one_vblank wait for one vblank void drm_wait_one_vblank struct drm_device * dev int crtc dev DRM device crtc crtc index This waits for one vblank to pass on crtc, using the irq driver interfaces. It is a failure to call this when the vblank irq for crtc is disabled, e.g. due to lack of driver support or because the crtc is off. Kernel Hackers Manual July 2017 drm_crtc_wait_one_vblank 9 4.1.27 drm_crtc_wait_one_vblank wait for one vblank void drm_crtc_wait_one_vblank struct drm_crtc * crtc crtc DRM crtc This waits for one vblank to pass on crtc, using the irq driver interfaces. It is a failure to call this when the vblank irq for crtc is disabled, e.g. due to lack of driver support or because the crtc is off. Kernel Hackers Manual July 2017 drm_vblank_off 9 4.1.27 drm_vblank_off disable vblank events on a CRTC void drm_vblank_off struct drm_device * dev int crtc dev DRM device crtc CRTC in question Drivers can use this function to shut down the vblank interrupt handling when disabling a crtc. This function ensures that the latest vblank frame count is stored so that drm_vblank_on can restore it again. Drivers must use this function when the hardware vblank counter can get reset, e.g. when suspending. This is the legacy version of drm_crtc_vblank_off. Kernel Hackers Manual July 2017 drm_crtc_vblank_off 9 4.1.27 drm_crtc_vblank_off disable vblank events on a CRTC void drm_crtc_vblank_off struct drm_crtc * crtc crtc CRTC in question Drivers can use this function to shut down the vblank interrupt handling when disabling a crtc. This function ensures that the latest vblank frame count is stored so that drm_vblank_on can restore it again. Drivers must use this function when the hardware vblank counter can get reset, e.g. when suspending. This is the native kms version of drm_vblank_off. Kernel Hackers Manual July 2017 drm_crtc_vblank_reset 9 4.1.27 drm_crtc_vblank_reset reset vblank state to off on a CRTC void drm_crtc_vblank_reset struct drm_crtc * drm_crtc drm_crtc -- undescribed -- Drivers can use this function to reset the vblank state to off at load time. Drivers should use this together with the drm_crtc_vblank_off and drm_crtc_vblank_on functions. The difference compared to drm_crtc_vblank_off is that this function doesn't save the vblank counter and hence doesn't need to call any driver hooks. Kernel Hackers Manual July 2017 drm_vblank_on 9 4.1.27 drm_vblank_on enable vblank events on a CRTC void drm_vblank_on struct drm_device * dev int crtc dev DRM device crtc CRTC in question This functions restores the vblank interrupt state captured with drm_vblank_off again. Note that calls to drm_vblank_on and drm_vblank_off can be unbalanced and so can also be unconditionally called in driver load code to reflect the current hardware state of the crtc. This is the legacy version of drm_crtc_vblank_on. Kernel Hackers Manual July 2017 drm_crtc_vblank_on 9 4.1.27 drm_crtc_vblank_on enable vblank events on a CRTC void drm_crtc_vblank_on struct drm_crtc * crtc crtc CRTC in question This functions restores the vblank interrupt state captured with drm_vblank_off again. Note that calls to drm_vblank_on and drm_vblank_off can be unbalanced and so can also be unconditionally called in driver load code to reflect the current hardware state of the crtc. This is the native kms version of drm_vblank_on. Kernel Hackers Manual July 2017 drm_vblank_pre_modeset 9 4.1.27 drm_vblank_pre_modeset account for vblanks across mode sets void drm_vblank_pre_modeset struct drm_device * dev int crtc dev DRM device crtc CRTC in question Account for vblank events across mode setting events, which will likely reset the hardware frame counter. This is done by grabbing a temporary vblank reference to ensure that the vblank interrupt keeps running across the modeset sequence. With this the software-side vblank frame counting will ensure that there are no jumps or discontinuities. Unfortunately this approach is racy and also doesn't work when the vblank interrupt stops running, e.g. across system suspend resume. It is therefore highly recommended that drivers use the newer drm_vblank_off and drm_vblank_on instead. drm_vblank_pre_modeset only works correctly when using cooked software vblank frame counters and not relying on any hardware counters. Drivers must call drm_vblank_post_modeset when re-enabling the same crtc again. Kernel Hackers Manual July 2017 drm_vblank_post_modeset 9 4.1.27 drm_vblank_post_modeset undo drm_vblank_pre_modeset changes void drm_vblank_post_modeset struct drm_device * dev int crtc dev DRM device crtc CRTC in question This function again drops the temporary vblank reference acquired in drm_vblank_pre_modeset. Kernel Hackers Manual July 2017 drm_handle_vblank 9 4.1.27 drm_handle_vblank handle a vblank event bool drm_handle_vblank struct drm_device * dev int crtc dev DRM device crtc where this event occurred Drivers should call this routine in their vblank interrupt handlers to update the vblank counter and send any signals that may be pending. This is the legacy version of drm_crtc_handle_vblank. Kernel Hackers Manual July 2017 drm_crtc_handle_vblank 9 4.1.27 drm_crtc_handle_vblank handle a vblank event bool drm_crtc_handle_vblank struct drm_crtc * crtc crtc where this event occurred Drivers should call this routine in their vblank interrupt handlers to update the vblank counter and send any signals that may be pending. This is the native KMS version of drm_handle_vblank. True if the event was successfully handled, false on failure. Kernel Hackers Manual July 2017 drm_crtc_vblank_waitqueue 9 4.1.27 drm_crtc_vblank_waitqueue get vblank waitqueue for the CRTC wait_queue_head_t * drm_crtc_vblank_waitqueue struct drm_crtc * crtc crtc which CRTC's vblank waitqueue to retrieve This function returns a pointer to the vblank waitqueue for the CRTC. Drivers can use this to implement vblank waits using wait_event & co. int (*firstopen) (struct drm_device *); void (*lastclose) (struct drm_device *); int (*open) (struct drm_device *, struct drm_file *); void (*preclose) (struct drm_device *, struct drm_file *); void (*postclose) (struct drm_device *, struct drm_file *); Open and close handlers. None of those methods are mandatory. The firstopen method is called by the DRM core for legacy UMS (User Mode Setting) drivers only when an application opens a device that has no other opened file handle. UMS drivers can implement it to acquire device resources. KMS drivers can't use the method and must acquire resources in the load method instead. Similarly the lastclose method is called when the last application holding a file handle opened on the device closes it, for both UMS and KMS drivers. Additionally, the method is also called at module unload time or, for hot-pluggable devices, when the device is unplugged. The firstopen and lastclose calls can thus be unbalanced. The open method is called every time the device is opened by an application. Drivers can allocate per-file private data in this method and store them in the struct drm_file driver_priv field. Note that the open method is called before firstopen. The close operation is split into preclose and postclose methods. Drivers must stop and cleanup all per-file operations in the preclose method. For instance pending vertical blanking and page flip events must be cancelled. No per-file operation is allowed on the file handle after returning from the preclose method. Finally the postclose method is called as the last step of the close operation, right before calling the lastclose method if no other open file handle exists for the device. Drivers that have allocated per-file private data in the open method should free it here. The lastclose method should restore CRTC and plane properties to default value, so that a subsequent open of the device will not inherit state from the previous user. It can also be used to execute delayed power switching state changes, e.g. in conjunction with the vga-switcheroo infrastructure. Beyond that KMS drivers should not do any further cleanup. Only legacy UMS drivers might need to clean up device state so that the vga console or an independent fbdev driver could take over. const struct file_operations *fops File operations for the DRM device node. Drivers must define the file operations structure that forms the DRM userspace API entry point, even though most of those operations are implemented in the DRM core. The open, release and ioctl operations are handled by .owner = THIS_MODULE, .open = drm_open, .release = drm_release, .unlocked_ioctl = drm_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = drm_compat_ioctl, #endif Drivers that implement private ioctls that requires 32/64bit compatibility support must provide their own compat_ioctl handler that processes private ioctls and calls drm_compat_ioctl for core ioctls. The read and poll operations provide support for reading DRM events and polling them. They are implemented by .poll = drm_poll, .read = drm_read, .llseek = no_llseek, The memory mapping implementation varies depending on how the driver manages memory. Pre-GEM drivers will use drm_mmap, while GEM-aware drivers will use drm_gem_mmap. See . .mmap = drm_gem_mmap, No other file operation is supported by the DRM API. struct drm_ioctl_desc *ioctls; int num_ioctls; Driver-specific ioctls descriptors table. Driver-specific ioctls numbers start at DRM_COMMAND_BASE. The ioctls descriptors table is indexed by the ioctl number offset from the base value. Drivers can use the DRM_IOCTL_DEF_DRV() macro to initialize the table entries. DRM_IOCTL_DEF_DRV(ioctl, func, flags) ioctl is the ioctl name. Drivers must define the DRM_##ioctl and DRM_IOCTL_##ioctl macros to the ioctl number offset from DRM_COMMAND_BASE and the ioctl number respectively. The first macro is private to the device while the second must be exposed to userspace in a public header. func is a pointer to the ioctl handler function compatible with the drm_ioctl_t type. typedef int drm_ioctl_t(struct drm_device *dev, void *data, struct drm_file *file_priv); flags is a bitmask combination of the following values. It restricts how the ioctl is allowed to be called. DRM_AUTH - Only authenticated callers allowed DRM_MASTER - The ioctl can only be called on the master file handle DRM_ROOT_ONLY - Only callers with the SYSADMIN capability allowed DRM_CONTROL_ALLOW - The ioctl can only be called on a control device DRM_UNLOCKED - The ioctl handler will be called without locking the DRM global mutex The section very briefly covers some of the old legacy support code which is only used by old DRM drivers which have done a so-called shadow-attach to the underlying device instead of registering as a real driver. This also includes some of the old generic buffer management and command submission code. Do not use any of this in new and modern drivers. The DRM core provides some suspend/resume code, but drivers wanting full suspend/resume support should provide save() and restore() functions. These are called at suspend, hibernate, or resume time, and should perform any state save or restore required by your device across suspend or hibernate states. int (*suspend) (struct drm_device *, pm_message_t state); int (*resume) (struct drm_device *); Those are legacy suspend and resume methods which only work with the legacy shadow-attach driver registration functions. New driver should use the power management interface provided by their bus type (usually through the struct device_driver dev_pm_ops) and set these methods to NULL. This should cover how DMA mapping etc. is supported by the core. These functions are deprecated and should not be used. The DRM core exports several interfaces to applications, generally intended to be used through corresponding libdrm wrapper functions. In addition, drivers export device-specific interfaces for use by userspace drivers & device-aware applications through ioctls and sysfs files. External interfaces include: memory mapping, context management, DMA operations, AGP management, vblank control, fence management, memory management, and output management. Cover generic ioctls and sysfs layout here. We only need high-level info, since man pages should cover the rest. DRM core provides multiple character-devices for user-space to use. Depending on which device is opened, user-space can perform a different set of operations (mainly ioctls). The primary node is always created and called card<num>. Additionally, a currently unused control node, called controlD<num> is also created. The primary node provides all legacy operations and historically was the only interface used by userspace. With KMS, the control node was introduced. However, the planned KMS control interface has never been written and so the control node stays unused to date. With the increased use of offscreen renderers and GPGPU applications, clients no longer require running compositors or graphics servers to make use of a GPU. But the DRM API required unprivileged clients to authenticate to a DRM-Master prior to getting GPU access. To avoid this step and to grant clients GPU access without authenticating, render nodes were introduced. Render nodes solely serve render clients, that is, no modesetting or privileged ioctls can be issued on render nodes. Only non-global rendering commands are allowed. If a driver supports render nodes, it must advertise it via the DRIVER_RENDER DRM driver capability. If not supported, the primary node must be used for render clients together with the legacy drmAuth authentication procedure. If a driver advertises render node support, DRM core will create a separate render node called renderD<num>. There will be one render node per device. No ioctls except PRIME-related ioctls will be allowed on this node. Especially GEM_OPEN will be explicitly prohibited. Render nodes are designed to avoid the buffer-leaks, which occur if clients guess the flink names or mmap offsets on the legacy interface. Additionally to this basic interface, drivers must mark their driver-dependent render-only ioctls as DRM_RENDER_ALLOW so render clients can use them. Driver authors must be careful not to allow any privileged ioctls on render nodes. With render nodes, user-space can now control access to the render node via basic file-system access-modes. A running graphics server which authenticates clients on the privileged primary/legacy node is no longer required. Instead, a client can open the render node and is immediately granted GPU access. Communication between clients (or servers) is done via PRIME. FLINK from render node to legacy node is not supported. New clients must not use the insecure FLINK interface. Besides dropping all modeset/global ioctls, render nodes also drop the DRM-Master concept. There is no reason to associate render clients with a DRM-Master as they are independent of any graphics server. Besides, they must work without any running master, anyway. Drivers must be able to run without a master object if they support render nodes. If, on the other hand, a driver requires shared state between clients which is visible to user-space and accessible beyond open-file boundaries, they cannot support render nodes. The DRM core exposes two vertical blank related ioctls: DRM_IOCTL_WAIT_VBLANK This takes a struct drm_wait_vblank structure as its argument, and it is used to block or request a signal when a specified vblank event occurs. DRM_IOCTL_MODESET_CTL This was only used for user-mode-settind drivers around modesetting changes to allow the kernel to update the vblank interrupt after mode setting, since on many devices the vertical blank counter is reset to 0 at some point during modeset. Modern drivers should not call this any more since with kernel mode setting it is a no-op. This second part of the DRM Developer's Guide documents driver code, implementation details and also all the driver-specific userspace interfaces. Especially since all hardware-acceleration interfaces to userspace are driver specific for efficiency and other reasons these interfaces can be rather substantial. Hence every driver has its own chapter. The drm/i915 driver supports all (with the exception of some very early models) integrated GFX chipsets with both Intel display and rendering blocks. This excludes a set of SoC platforms with an SGX rendering unit, those have basic support through the gma500 drm driver. This section covers core driver infrastructure used by both the display and the GEM parts of the driver. The i915 driver supports dynamic enabling and disabling of entire hardware blocks at runtime. This is especially important on the display side where software is supposed to control many power gates manually on recent hardware, since on the GT side a lot of the power management is done by the hardware. But even there some manual control at the device level is required. Since i915 supports a diverse set of platforms with a unified codebase and hardware engineers just love to shuffle functionality around between power domains there's a sizeable amount of indirection required. This file provides generic functions to the driver for grabbing and releasing references for abstract power domains. It then maps those to the actual power wells present for a given platform. Kernel Hackers Manual July 2017 __intel_display_power_is_enabled 9 4.1.27 __intel_display_power_is_enabled unlocked check for a power domain bool __intel_display_power_is_enabled struct drm_i915_private * dev_priv enum intel_display_power_domain domain dev_priv i915 device instance domain power domain to check This is the unlocked version of intel_display_power_is_enabled and should only be used from error capture and recovery code where deadlocks are possible. True when the power domain is enabled, false otherwise. Kernel Hackers Manual July 2017 intel_display_power_is_enabled 9 4.1.27 intel_display_power_is_enabled check for a power domain bool intel_display_power_is_enabled struct drm_i915_private * dev_priv enum intel_display_power_domain domain dev_priv i915 device instance domain power domain to check This function can be used to check the hw power domain state. It is mostly used in hardware state readout functions. Everywhere else code should rely upon explicit power domain reference counting to ensure that the hardware block is powered up before accessing it. Callers must hold the relevant modesetting locks to ensure that concurrent threads can't disable the power well while the caller tries to read a few registers. True when the power domain is enabled, false otherwise. Kernel Hackers Manual July 2017 intel_display_set_init_power 9 4.1.27 intel_display_set_init_power set the initial power domain state void intel_display_set_init_power struct drm_i915_private * dev_priv bool enable dev_priv i915 device instance enable whether to enable or disable the initial power domain state For simplicity our driver load/unload and system suspend/resume code assumes that all power domains are always enabled. This functions controls the state of this little hack. While the initial power domain state is enabled runtime pm is effectively disabled. Kernel Hackers Manual July 2017 intel_display_power_get 9 4.1.27 intel_display_power_get grab a power domain reference void intel_display_power_get struct drm_i915_private * dev_priv enum intel_display_power_domain domain dev_priv i915 device instance domain power domain to reference This function grabs a power domain reference for domain and ensures that the power domain and all its parents are powered up. Therefore users should only grab a reference to the innermost power domain they need. Any power domain reference obtained by this function must have a symmetric call to intel_display_power_put to release the reference again. Kernel Hackers Manual July 2017 intel_display_power_put 9 4.1.27 intel_display_power_put release a power domain reference void intel_display_power_put struct drm_i915_private * dev_priv enum intel_display_power_domain domain dev_priv i915 device instance domain power domain to reference This function drops the power domain reference obtained by intel_display_power_get and might power down the corresponding hardware block right away if this is the last reference. Kernel Hackers Manual July 2017 intel_power_domains_init 9 4.1.27 intel_power_domains_init initializes the power domain structures int intel_power_domains_init struct drm_i915_private * dev_priv dev_priv i915 device instance Initializes the power domain structures for dev_priv depending upon the supported platform. Kernel Hackers Manual July 2017 intel_power_domains_fini 9 4.1.27 intel_power_domains_fini finalizes the power domain structures void intel_power_domains_fini struct drm_i915_private * dev_priv dev_priv i915 device instance Finalizes the power domain structures for dev_priv depending upon the supported platform. This function also disables runtime pm and ensures that the device stays powered up so that the driver can be reloaded. Kernel Hackers Manual July 2017 intel_power_domains_init_hw 9 4.1.27 intel_power_domains_init_hw initialize hardware power domain state void intel_power_domains_init_hw struct drm_i915_private * dev_priv dev_priv i915 device instance This function initializes the hardware power domain state and enables all power domains using intel_display_set_init_power. Kernel Hackers Manual July 2017 intel_aux_display_runtime_get 9 4.1.27 intel_aux_display_runtime_get grab an auxiliary power domain reference void intel_aux_display_runtime_get struct drm_i915_private * dev_priv dev_priv i915 device instance This function grabs a power domain reference for the auxiliary power domain (for access to the GMBUS and DP AUX blocks) and ensures that it and all its parents are powered up. Therefore users should only grab a reference to the innermost power domain they need. Any power domain reference obtained by this function must have a symmetric call to intel_aux_display_runtime_put to release the reference again. Kernel Hackers Manual July 2017 intel_aux_display_runtime_put 9 4.1.27 intel_aux_display_runtime_put release an auxiliary power domain reference void intel_aux_display_runtime_put struct drm_i915_private * dev_priv dev_priv i915 device instance This function drops the auxiliary power domain reference obtained by intel_aux_display_runtime_get and might power down the corresponding hardware block right away if this is the last reference. Kernel Hackers Manual July 2017 intel_runtime_pm_get 9 4.1.27 intel_runtime_pm_get grab a runtime pm reference void intel_runtime_pm_get struct drm_i915_private * dev_priv dev_priv i915 device instance This function grabs a device-level runtime pm reference (mostly used for GEM code to ensure the GTT or GT is on) and ensures that it is powered up. Any runtime pm reference obtained by this function must have a symmetric call to intel_runtime_pm_put to release the reference again. Kernel Hackers Manual July 2017 intel_runtime_pm_get_noresume 9 4.1.27 intel_runtime_pm_get_noresume grab a runtime pm reference void intel_runtime_pm_get_noresume struct drm_i915_private * dev_priv dev_priv i915 device instance This function grabs a device-level runtime pm reference (mostly used for GEM code to ensure the GTT or GT is on). It will _not_ power up the device but instead only check that it's powered on. Therefore it is only valid to call this functions from contexts where the device is known to be powered up and where trying to power it up would result in hilarity and deadlocks. That pretty much means only the system suspend/resume code where this is used to grab runtime pm references for delayed setup down in work items. Any runtime pm reference obtained by this function must have a symmetric call to intel_runtime_pm_put to release the reference again. Kernel Hackers Manual July 2017 intel_runtime_pm_put 9 4.1.27 intel_runtime_pm_put release a runtime pm reference void intel_runtime_pm_put struct drm_i915_private * dev_priv dev_priv i915 device instance This function drops the device-level runtime pm reference obtained by intel_runtime_pm_get and might power down the corresponding hardware block right away if this is the last reference. Kernel Hackers Manual July 2017 intel_runtime_pm_enable 9 4.1.27 intel_runtime_pm_enable enable runtime pm void intel_runtime_pm_enable struct drm_i915_private * dev_priv dev_priv i915 device instance This function enables runtime pm at the end of the driver load sequence. Note that this function does currently not enable runtime pm for the subordinate display power domains. That is only done on the first modeset using intel_display_set_init_power. Kernel Hackers Manual July 2017 intel_uncore_forcewake_get 9 4.1.27 intel_uncore_forcewake_get grab forcewake domain references void intel_uncore_forcewake_get struct drm_i915_private * dev_priv enum forcewake_domains fw_domains dev_priv i915 device instance fw_domains forcewake domains to get reference on This function can be used get GT's forcewake domain references. Normal register access will handle the forcewake domains automatically. However if some sequence requires the GT to not power down a particular forcewake domains this function should be called at the beginning of the sequence. And subsequently the reference should be dropped by symmetric call to intel_unforce_forcewake_put. Usually caller wants all the domains to be kept awake so the fw_domains would be then FORCEWAKE_ALL. Kernel Hackers Manual July 2017 intel_uncore_forcewake_put 9 4.1.27 intel_uncore_forcewake_put release a forcewake domain reference void intel_uncore_forcewake_put struct drm_i915_private * dev_priv enum forcewake_domains fw_domains dev_priv i915 device instance fw_domains forcewake domains to put references This function drops the device-level forcewakes for specified domains obtained by intel_uncore_forcewake_get. These functions provide the basic support for enabling and disabling the interrupt handling support. There's a lot more functionality in i915_irq.c and related files, but that will be described in separate chapters. Kernel Hackers Manual July 2017 intel_irq_init 9 4.1.27 intel_irq_init initializes irq support void intel_irq_init struct drm_i915_private * dev_priv dev_priv i915 device instance This function initializes all the irq support including work items, timers and all the vtables. It does not setup the interrupt itself though. Kernel Hackers Manual July 2017 intel_hpd_init 9 4.1.27 intel_hpd_init initializes and enables hpd support void intel_hpd_init struct drm_i915_private * dev_priv dev_priv i915 device instance This function enables the hotplug support. It requires that interrupts have already been enabled with intel_irq_init_hw. From this point on hotplug and poll request can run concurrently to other code, so locking rules must be obeyed. This is a separate step from interrupt enabling to simplify the locking rules in the driver load and resume code. .//drivers/gpu/drm/i915/i915_irq.c Document generation inconsistency The template for this document tried to insert the structured comment from the file .//drivers/gpu/drm/i915/i915_irq.c at this point, but none was found. This dummy section is inserted to allow generation to continue. Kernel Hackers Manual July 2017 intel_runtime_pm_disable_interrupts 9 4.1.27 intel_runtime_pm_disable_interrupts runtime interrupt disabling void intel_runtime_pm_disable_interrupts struct drm_i915_private * dev_priv dev_priv i915 device instance This function is used to disable interrupts at runtime, both in the runtime pm and the system suspend/resume code. Kernel Hackers Manual July 2017 intel_runtime_pm_enable_interrupts 9 4.1.27 intel_runtime_pm_enable_interrupts runtime interrupt enabling void intel_runtime_pm_enable_interrupts struct drm_i915_private * dev_priv dev_priv i915 device instance This function is used to enable interrupts at runtime, both in the runtime pm and the system suspend/resume code. Intel GVT-g is a graphics virtualization technology which shares the GPU among multiple virtual machines on a time-sharing basis. Each virtual machine is presented a virtual GPU (vGPU), which has equivalent features as the underlying physical GPU (pGPU), so i915 driver can run seamlessly in a virtual machine. This file provides vGPU specific optimizations when running in a virtual machine, to reduce the complexity of vGPU emulation and to improve the overall performance. A primary function introduced here is so-called address space ballooning technique. Intel GVT-g partitions global graphics memory among multiple VMs, so each VM can directly access a portion of the memory without hypervisor's intervention, e.g. filling textures or queuing commands. However with the partitioning an unmodified i915 driver would assume a smaller graphics memory starting from address ZERO, then requires vGPU emulation module to translate the graphics address between 'guest view' and 'host view', for all registers and command opcodes which contain a graphics memory address. To reduce the complexity, Intel GVT-g introduces address space ballooning, by telling the exact partitioning knowledge to each guest i915 driver, which then reserves and prevents non-allocated portions from allocation. Thus vGPU emulation module only needs to scan and validate graphics addresses without complexity of address translation. Kernel Hackers Manual July 2017 i915_check_vgpu 9 4.1.27 i915_check_vgpu detect virtual GPU void i915_check_vgpu struct drm_device * dev dev drm device * This function is called at the initialization stage, to detect whether running on a vGPU. Kernel Hackers Manual July 2017 intel_vgt_deballoon 9 4.1.27 intel_vgt_deballoon deballoon reserved graphics address trunks void intel_vgt_deballoon void void no arguments This function is called to deallocate the ballooned-out graphic memory, when driver is unloaded or when ballooning fails. Kernel Hackers Manual July 2017 intel_vgt_balloon 9 4.1.27 intel_vgt_balloon balloon out reserved graphics address trunks int intel_vgt_balloon struct drm_device * dev dev drm device This function is called at the initialization stage, to balloon out the graphic address space allocated to other vGPUs, by marking these spaces as reserved. The ballooning related knowledge(starting address and size of the mappable/unmappable graphic memory) is described in the vgt_if structure in a reserved mmio range. To give an example, the drawing below depicts one typical scenario after ballooning. Here the vGPU1 has 2 pieces of graphic address spaces ballooned out each for the mappable and the non-mappable part. From the vGPU1 point of view, the total size is the same as the physical one, with the start address of its graphic space being zero. Yet there are some portions ballooned out( the shadow part, which are marked as reserved by drm allocator). From the host point of view, the graphic address space is partitioned by multiple vGPUs in different VMs. vGPU1 view Host view 0 ------> +-----------+ +-----------+ ^ |///////////| | vGPU3 | | |///////////| +-----------+ | |///////////| | vGPU2 | | +-----------+ +-----------+ mappable GM | available | ==> | vGPU1 | | +-----------+ +-----------+ | |///////////| | | v |///////////| | Host | +=======+===========+ +===========+ ^ |///////////| | vGPU3 | | |///////////| +-----------+ | |///////////| | vGPU2 | | +-----------+ +-----------+ unmappable GM | available | ==> | vGPU1 | | +-----------+ +-----------+ | |///////////| | | | |///////////| | Host | v |///////////| | | total GM size ------> +-----------+ +-----------+ zero on success, non-zero if configuration invalid or ballooning failed This section covers everything related to the display hardware including the mode setting infrastructure, plane, sprite and cursor handling and display, output probing and related topics. The i915 driver is thus far the only DRM driver which doesn't use the common DRM helper code to implement mode setting sequences. Thus it has its own tailor-made infrastructure for executing a display configuration change. Many features require us to track changes to the currently active frontbuffer, especially rendering targeted at the frontbuffer. To be able to do so GEM tracks frontbuffers using a bitmask for all possible frontbuffer slots through i915_gem_track_fb. The function in this file are then called when the contents of the frontbuffer are invalidated, when frontbuffer rendering has stopped again to flush out all the changes and when the frontbuffer is exchanged with a flip. Subsystems interested in frontbuffer changes (e.g. PSR, FBC, DRRS) should directly put their callbacks into the relevant places and filter for the frontbuffer slots that they are interested int. On a high level there are two types of powersaving features. The first one work like a special cache (FBC and PSR) and are interested when they should stop caching and when to restart caching. This is done by placing callbacks into the invalidate and the flush functions: At invalidate the caching must be stopped and at flush time it can be restarted. And maybe they need to know when the frontbuffer changes (e.g. when the hw doesn't initiate an invalidate and flush on its own) which can be achieved with placing callbacks into the flip functions. The other type of display power saving feature only cares about busyness (e.g. DRRS). In that case all three (invalidate, flush and flip) indicate busyness. There is no direct way to detect idleness. Instead an idle timer work delayed work should be started from the flush and flip functions and cancelled as soon as busyness is detected. Note that there's also an older frontbuffer activity tracking scheme which just tracks general activity. This is done by the various mark_busy and mark_idle functions. For display power management features using these functions is deprecated and should be avoided. Kernel Hackers Manual July 2017 intel_mark_fb_busy 9 4.1.27 intel_mark_fb_busy mark given planes as busy void intel_mark_fb_busy struct drm_device * dev unsigned frontbuffer_bits struct intel_engine_cs * ring dev DRM device frontbuffer_bits bits for the affected planes ring optional ring for asynchronous commands This function gets called every time the screen contents change. It can be used to keep e.g. the update rate at the nominal refresh rate with DRRS. Kernel Hackers Manual July 2017 intel_fb_obj_invalidate 9 4.1.27 intel_fb_obj_invalidate invalidate frontbuffer object void intel_fb_obj_invalidate struct drm_i915_gem_object * obj struct intel_engine_cs * ring enum fb_op_origin origin obj GEM object to invalidate ring set for asynchronous rendering origin which operation caused the invalidation This function gets called every time rendering on the given object starts and frontbuffer caching (fbc, low refresh rate for DRRS, panel self refresh) must be invalidated. If ring is non-NULL any subsequent invalidation will be delayed until the rendering completes or a flip on this frontbuffer plane is scheduled. Kernel Hackers Manual July 2017 intel_frontbuffer_flush 9 4.1.27 intel_frontbuffer_flush flush frontbuffer void intel_frontbuffer_flush struct drm_device * dev unsigned frontbuffer_bits dev DRM device frontbuffer_bits frontbuffer plane tracking bits This function gets called every time rendering on the given planes has completed and frontbuffer caching can be started again. Flushes will get delayed if they're blocked by some outstanding asynchronous rendering. Can be called without any locks held. Kernel Hackers Manual July 2017 intel_fb_obj_flush 9 4.1.27 intel_fb_obj_flush flush frontbuffer object void intel_fb_obj_flush struct drm_i915_gem_object * obj bool retire obj GEM object to flush retire set when retiring asynchronous rendering This function gets called every time rendering on the given object has completed and frontbuffer caching can be started again. If retire is true then any delayed flushes will be unblocked. Kernel Hackers Manual July 2017 intel_frontbuffer_flip_prepare 9 4.1.27 intel_frontbuffer_flip_prepare prepare asynchronous frontbuffer flip void intel_frontbuffer_flip_prepare struct drm_device * dev unsigned frontbuffer_bits dev DRM device frontbuffer_bits frontbuffer plane tracking bits This function gets called after scheduling a flip on obj. The actual frontbuffer flushing will be delayed until completion is signalled with intel_frontbuffer_flip_complete. If an invalidate happens in between this flush will be cancelled. Can be called without any locks held. Kernel Hackers Manual July 2017 intel_frontbuffer_flip_complete 9 4.1.27 intel_frontbuffer_flip_complete complete asynchronous frontbuffer flip void intel_frontbuffer_flip_complete struct drm_device * dev unsigned frontbuffer_bits dev DRM device frontbuffer_bits frontbuffer plane tracking bits This function gets called after the flip has been latched and will complete on the next vblank. It will execute the flush if it hasn't been cancelled yet. Can be called without any locks held. Kernel Hackers Manual July 2017 intel_frontbuffer_flip 9 4.1.27 intel_frontbuffer_flip synchronous frontbuffer flip void intel_frontbuffer_flip struct drm_device * dev unsigned frontbuffer_bits dev DRM device frontbuffer_bits frontbuffer plane tracking bits This function gets called after scheduling a flip on obj. This is for synchronous plane updates which will happen on the next vblank and which will not get delayed by pending gpu rendering. Can be called without any locks held. Kernel Hackers Manual July 2017 i915_gem_track_fb 9 4.1.27 i915_gem_track_fb update frontbuffer tracking void i915_gem_track_fb struct drm_i915_gem_object * old struct drm_i915_gem_object * new unsigned frontbuffer_bits old -- undescribed -- new -- undescribed -- frontbuffer_bits -- undescribed -- current GEM buffer for the frontbuffer slots new GEM buffer for the frontbuffer slots bitmask of frontbuffer slots This updates the frontbuffer tracking bits frontbuffer_bits by clearing them from old and setting them in new. Both old and new can be NULL. The i915 driver checks for display fifo underruns using the interrupt signals provided by the hardware. This is enabled by default and fairly useful to debug display issues, especially watermark settings. If an underrun is detected this is logged into dmesg. To avoid flooding logs and occupying the cpu underrun interrupts are disabled after the first occurrence until the next modeset on a given pipe. Note that underrun detection on gmch platforms is a bit more ugly since there is no interrupt (despite that the signalling bit is in the PIPESTAT pipe interrupt register). Also on some other platforms underrun interrupts are shared, which means that if we detect an underrun we need to disable underrun reporting on all pipes. The code also supports underrun detection on the PCH transcoder. Kernel Hackers Manual July 2017 i9xx_check_fifo_underruns 9 4.1.27 i9xx_check_fifo_underruns check for fifo underruns void i9xx_check_fifo_underruns struct drm_i915_private * dev_priv dev_priv i915 device instance This function checks for fifo underruns on GMCH platforms. This needs to be done manually on modeset to make sure that we catch all underruns since they do not generate an interrupt by themselves on these platforms. Kernel Hackers Manual July 2017 intel_set_cpu_fifo_underrun_reporting 9 4.1.27 intel_set_cpu_fifo_underrun_reporting set cpu fifo underrrun reporting state bool intel_set_cpu_fifo_underrun_reporting struct drm_i915_private * dev_priv enum pipe pipe bool enable dev_priv i915 device instance pipe (CPU) pipe to set state for enable whether underruns should be reported or not This function sets the fifo underrun state for pipe. It is used in the modeset code to avoid false positives since on many platforms underruns are expected when disabling or enabling the pipe. Notice that on some platforms disabling underrun reports for one pipe disables for all due to shared interrupts. Actual reporting is still per-pipe though. Returns the previous state of underrun reporting. Kernel Hackers Manual July 2017 intel_set_pch_fifo_underrun_reporting 9 4.1.27 intel_set_pch_fifo_underrun_reporting set PCH fifo underrun reporting state bool intel_set_pch_fifo_underrun_reporting struct drm_i915_private * dev_priv enum transcoder pch_transcoder bool enable dev_priv i915 device instance pch_transcoder the PCH transcoder (same as pipe on IVB and older) enable whether underruns should be reported or not This function makes us disable or enable PCH fifo underruns for a specific PCH transcoder. Notice that on some PCHs (e.g. CPT/PPT), disabling FIFO underrun reporting for one transcoder may also disable all the other PCH error interruts for the other transcoders, due to the fact that there's just one interrupt mask/enable bit for all the transcoders. Returns the previous state of underrun reporting. Kernel Hackers Manual July 2017 intel_cpu_fifo_underrun_irq_handler 9 4.1.27 intel_cpu_fifo_underrun_irq_handler handle CPU fifo underrun interrupt void intel_cpu_fifo_underrun_irq_handler struct drm_i915_private * dev_priv enum pipe pipe dev_priv i915 device instance pipe (CPU) pipe to set state for This handles a CPU fifo underrun interrupt, generating an underrun warning into dmesg if underrun reporting is enabled and then disables the underrun interrupt to avoid an irq storm. Kernel Hackers Manual July 2017 intel_pch_fifo_underrun_irq_handler 9 4.1.27 intel_pch_fifo_underrun_irq_handler handle PCH fifo underrun interrupt void intel_pch_fifo_underrun_irq_handler struct drm_i915_private * dev_priv enum transcoder pch_transcoder dev_priv i915 device instance pch_transcoder the PCH transcoder (same as pipe on IVB and older) This handles a PCH fifo underrun interrupt, generating an underrun warning into dmesg if underrun reporting is enabled and then disables the underrun interrupt to avoid an irq storm. This section covers plane configuration and composition with the primary plane, sprites, cursors and overlays. This includes the infrastructure to do atomic vsync'ed updates of all this state and also tightly coupled topics like watermark setup and computation, framebuffer compression and panel self refresh. The functions here are used by the atomic plane helper functions to implement legacy plane updates (i.e., drm_plane->update_plane and drm_plane->disable_plane). This allows plane updates to use the atomic state infrastructure and perform plane updates as separate prepare/check/commit/cleanup steps. Kernel Hackers Manual July 2017 intel_create_plane_state 9 4.1.27 intel_create_plane_state create plane state object struct intel_plane_state * intel_create_plane_state struct drm_plane * plane plane drm plane Allocates a fresh plane state for the given plane and sets some of the state values to sensible initial values. A newly allocated plane state, or NULL on failure Kernel Hackers Manual July 2017 intel_plane_duplicate_state 9 4.1.27 intel_plane_duplicate_state duplicate plane state struct drm_plane_state * intel_plane_duplicate_state struct drm_plane * plane plane drm plane Allocates and returns a copy of the plane state (both common and Intel-specific) for the specified plane. The newly allocated plane state, or NULL on failure. Kernel Hackers Manual July 2017 intel_plane_destroy_state 9 4.1.27 intel_plane_destroy_state destroy plane state void intel_plane_destroy_state struct drm_plane * plane struct drm_plane_state * state plane drm plane state state object to destroy Destroys the plane state (both common and Intel-specific) for the specified plane. Kernel Hackers Manual July 2017 intel_plane_atomic_get_property 9 4.1.27 intel_plane_atomic_get_property fetch plane property value int intel_plane_atomic_get_property struct drm_plane * plane const struct drm_plane_state * state struct drm_property * property uint64_t * val plane plane to fetch property for state state containing the property value property property to look up val pointer to write property value into The DRM core does not store shadow copies of properties for atomic-capable drivers. This entrypoint is used to fetch the current value of a driver-specific plane property. Kernel Hackers Manual July 2017 intel_plane_atomic_set_property 9 4.1.27 intel_plane_atomic_set_property set plane property value int intel_plane_atomic_set_property struct drm_plane * plane struct drm_plane_state * state struct drm_property * property uint64_t val plane plane to set property for state state to update property value in property property to set val value to set property to Writes the specified property value for a plane into the provided atomic state object. Returns 0 on success, -EINVAL on unrecognized properties This section covers output probing and related infrastructure like the hotplug interrupt storm detection and mitigation code. Note that the i915 driver still uses most of the common DRM helper code for output probing, so those sections fully apply. The graphics and audio drivers together support High Definition Audio over HDMI and Display Port. The audio programming sequences are divided into audio codec and controller enable and disable sequences. The graphics driver handles the audio codec sequences, while the audio driver handles the audio controller sequences. The disable sequences must be performed before disabling the transcoder or port. The enable sequences may only be performed after enabling the transcoder and port, and after completed link training. The codec and controller sequences could be done either parallel or serial, but generally the ELDV/PD change in the codec sequence indicates to the audio driver that the controller sequence should start. Indeed, most of the co-operation between the graphics and audio drivers is handled via audio related registers. (The notable exception is the power management, not covered here.) Kernel Hackers Manual July 2017 intel_audio_codec_enable 9 4.1.27 intel_audio_codec_enable Enable the audio codec for HD audio void intel_audio_codec_enable struct intel_encoder * intel_encoder intel_encoder encoder on which to enable audio The enable sequences may only be performed after enabling the transcoder and port, and after completed link training. Kernel Hackers Manual July 2017 intel_audio_codec_disable 9 4.1.27 intel_audio_codec_disable Disable the audio codec for HD audio void intel_audio_codec_disable struct intel_encoder * encoder encoder encoder on which to disable audio The disable sequences must be performed before disabling the transcoder or port. Kernel Hackers Manual July 2017 intel_init_audio 9 4.1.27 intel_init_audio Set up chip specific audio functions void intel_init_audio struct drm_device * dev dev drm device Kernel Hackers Manual July 2017 i915_audio_component_init 9 4.1.27 i915_audio_component_init initialize and register the audio component void i915_audio_component_init struct drm_i915_private * dev_priv dev_priv i915 device instance This will register with the component framework a child component which will bind dynamically to the snd_hda_intel driver's corresponding master component when the latter is registered. During binding the child initializes an instance of struct i915_audio_component which it receives from the master. The master can then start to use the interface defined by this struct. Each side can break the binding at any point by deregistering its own component after which each side's component unbind callback is called. We ignore any error during registration and continue with reduced functionality (i.e. without HDMI audio). Kernel Hackers Manual July 2017 i915_audio_component_cleanup 9 4.1.27 i915_audio_component_cleanup deregister the audio component void i915_audio_component_cleanup struct drm_i915_private * dev_priv dev_priv i915 device instance Deregisters the audio component, breaking any existing binding to the corresponding snd_hda_intel driver's master component. Since Haswell Display controller supports Panel Self-Refresh on display panels witch have a remote frame buffer (RFB) implemented according to PSR spec in eDP1.3. PSR feature allows the display to go to lower standby states when system is idle but display is on as it eliminates display refresh request to DDR memory completely as long as the frame buffer for that display is unchanged. Panel Self Refresh must be supported by both Hardware (source) and Panel (sink). PSR saves power by caching the framebuffer in the panel RFB, which allows us to power down the link and memory controller. For DSI panels the same idea is called manual mode. The implementation uses the hardware-based PSR support which automatically enters/exits self-refresh mode. The hardware takes care of sending the required DP aux message and could even retrain the link (that part isn't enabled yet though). The hardware also keeps track of any frontbuffer changes to know when to exit self-refresh mode again. Unfortunately that part doesn't work too well, hence why the i915 PSR support uses the software frontbuffer tracking to make sure it doesn't miss a screen update. For this integration intel_psr_invalidate and intel_psr_flush get called by the frontbuffer tracking code. Note that because of locking issues the self-refresh re-enable code is done from a work queue, which must be correctly synchronized/cancelled when shutting down the pipe." Kernel Hackers Manual July 2017 intel_psr_enable 9 4.1.27 intel_psr_enable Enable PSR void intel_psr_enable struct intel_dp * intel_dp intel_dp Intel DP This function can only be called after the pipe is fully trained and enabled. Kernel Hackers Manual July 2017 intel_psr_disable 9 4.1.27 intel_psr_disable Disable PSR void intel_psr_disable struct intel_dp * intel_dp intel_dp Intel DP This function needs to be called before disabling pipe. Kernel Hackers Manual July 2017 intel_psr_invalidate 9 4.1.27 intel_psr_invalidate Invalidade PSR void intel_psr_invalidate struct drm_device * dev unsigned frontbuffer_bits dev DRM device frontbuffer_bits frontbuffer plane tracking bits Since the hardware frontbuffer tracking has gaps we need to integrate with the software frontbuffer tracking. This function gets called every time frontbuffer rendering starts and a buffer gets dirtied. PSR must be disabled if the frontbuffer mask contains a buffer relevant to PSR. Dirty frontbuffers relevant to PSR are tracked in busy_frontbuffer_bits." Kernel Hackers Manual July 2017 intel_psr_flush 9 4.1.27 intel_psr_flush Flush PSR void intel_psr_flush struct drm_device * dev unsigned frontbuffer_bits dev DRM device frontbuffer_bits frontbuffer plane tracking bits Since the hardware frontbuffer tracking has gaps we need to integrate with the software frontbuffer tracking. This function gets called every time frontbuffer rendering has completed and flushed out to memory. PSR can be enabled again if no other frontbuffer relevant to PSR is dirty. Dirty frontbuffers relevant to PSR are tracked in busy_frontbuffer_bits. Kernel Hackers Manual July 2017 intel_psr_init 9 4.1.27 intel_psr_init Init basic PSR work and mutex. void intel_psr_init struct drm_device * dev dev DRM device This function is called only once at driver load to initialize basic PSR stuff. FBC tries to save memory bandwidth (and so power consumption) by compressing the amount of memory used by the display. It is total transparent to user space and completely handled in the kernel. The benefits of FBC are mostly visible with solid backgrounds and variation-less patterns. It comes from keeping the memory footprint small and having fewer memory pages opened and accessed for refreshing the display. i915 is responsible to reserve stolen memory for FBC and configure its offset on proper registers. The hardware takes care of all compress/decompress. However there are many known cases where we have to forcibly disable it to allow proper screen updates. Kernel Hackers Manual July 2017 intel_fbc_enabled 9 4.1.27 intel_fbc_enabled Is FBC enabled? bool intel_fbc_enabled struct drm_device * dev dev the drm_device This function is used to verify the current state of FBC. This should be tracked in the plane config eventually instead of queried at runtime for most callers. Kernel Hackers Manual July 2017 intel_fbc_disable 9 4.1.27 intel_fbc_disable disable FBC void intel_fbc_disable struct drm_device * dev dev the drm_device This function disables FBC. Kernel Hackers Manual July 2017 intel_fbc_update 9 4.1.27 intel_fbc_update enable/disable FBC as needed void intel_fbc_update struct drm_device * dev dev the drm_device Set up the framebuffer compression hardware at mode set time. We - plane A only (on pre-965) - no pixel mulitply/line duplication - no alpha buffer discard - no dual wide - framebuffer <= max_hdisplay in width, max_vdisplay in height We can't assume that any compression will take place (worst case), so the compressed buffer has to be the same size as the uncompressed one. It also must reside (along with the line length buffer) in stolen memory. We need to enable/disable FBC on a global basis. Kernel Hackers Manual July 2017 intel_fbc_init 9 4.1.27 intel_fbc_init Initialize FBC void intel_fbc_init struct drm_i915_private * dev_priv dev_priv the i915 device This function might be called during PM init process. Display Refresh Rate Switching (DRRS) is a power conservation feature which enables swtching between low and high refresh rates, dynamically, based on the usage scenario. This feature is applicable for internal panels. Indication that the panel supports DRRS is given by the panel EDID, which would list multiple refresh rates for one resolution. DRRS is of 2 types - static and seamless. Static DRRS involves changing refresh rate (RR) by doing a full modeset (may appear as a blink on screen) and is used in dock-undock scenario. Seamless DRRS involves changing RR without any visual effect to the user and can be used during normal system usage. This is done by programming certain registers. Support for static/seamless DRRS may be indicated in the VBT based on inputs from the panel spec. DRRS saves power by switching to low RR based on usage scenarios. eDP DRRS:- The implementation is based on frontbuffer tracking implementation. When there is a disturbance on the screen triggered by user activity or a periodic system activity, DRRS is disabled (RR is changed to high RR). When there is no movement on screen, after a timeout of 1 second, a switch to low RR is made. For integration with frontbuffer tracking code, intel_edp_drrs_invalidate and intel_edp_drrs_flush are called. DRRS can be further extended to support other internal panels and also the scenario of video playback wherein RR is set based on the rate requested by userspace. Kernel Hackers Manual July 2017 intel_dp_set_drrs_state 9 4.1.27 intel_dp_set_drrs_state program registers for RR switch to take effect void intel_dp_set_drrs_state struct drm_device * dev int refresh_rate dev DRM device refresh_rate RR to be programmed This function gets called when refresh rate (RR) has to be changed from one frequency to another. Switches can be between high and low RR supported by the panel or to any other RR based on media playback (in this case, RR value needs to be passed from user space). The caller of this function needs to take a lock on dev_priv->drrs. Kernel Hackers Manual July 2017 intel_edp_drrs_enable 9 4.1.27 intel_edp_drrs_enable init drrs struct if supported void intel_edp_drrs_enable struct intel_dp * intel_dp intel_dp DP struct Initializes frontbuffer_bits and drrs.dp Kernel Hackers Manual July 2017 intel_edp_drrs_disable 9 4.1.27 intel_edp_drrs_disable Disable DRRS void intel_edp_drrs_disable struct intel_dp * intel_dp intel_dp DP struct Kernel Hackers Manual July 2017 intel_edp_drrs_invalidate 9 4.1.27 intel_edp_drrs_invalidate Invalidate DRRS void intel_edp_drrs_invalidate struct drm_device * dev unsigned frontbuffer_bits dev DRM device frontbuffer_bits frontbuffer plane tracking bits When there is a disturbance on screen (due to cursor movement/time update etc), DRRS needs to be invalidated, i.e. need to switch to high RR. Dirty frontbuffers relevant to DRRS are tracked in busy_frontbuffer_bits. Kernel Hackers Manual July 2017 intel_edp_drrs_flush 9 4.1.27 intel_edp_drrs_flush Flush DRRS void intel_edp_drrs_flush struct drm_device * dev unsigned frontbuffer_bits dev DRM device frontbuffer_bits frontbuffer plane tracking bits When there is no movement on screen, DRRS work can be scheduled. This DRRS work is responsible for setting relevant registers after a timeout of 1 second. Dirty frontbuffers relevant to DRRS are tracked in busy_frontbuffer_bits. Kernel Hackers Manual July 2017 intel_dp_drrs_init 9 4.1.27 intel_dp_drrs_init Init basic DRRS work and mutex. struct drm_display_mode * intel_dp_drrs_init struct intel_connector * intel_connector struct drm_display_mode * fixed_mode intel_connector eDP connector fixed_mode preferred mode of panel This function is called only once at driver load to initialize basic DRRS stuff. Downclock mode if panel supports it, else return NULL. DRRS support is determined by the presence of downclock mode (apart from VBT setting). VLV and CHV have slightly peculiar display PHYs for driving DP/HDMI ports. DPIO is the name given to such a display PHY. These PHYs don't follow the standard programming model using direct MMIO registers, and instead their registers must be accessed trough IOSF sideband. VLV has one such PHY for driving ports B and C, and CHV adds another PHY for driving port D. Each PHY responds to specific IOSF-SB port. Each display PHY is made up of one or two channels. Each channel houses a common lane part which contains the PLL and other common logic. CH0 common lane also contains the IOSF-SB logic for the Common Register Interface (CRI) ie. the DPIO registers. CRI clock must be running when any DPIO registers are accessed. In addition to having their own registers, the PHYs are also controlled through some dedicated signals from the display controller. These include PLL reference clock enable, PLL enable, and CRI clock selection, for example. Eeach channel also has two splines (also called data lanes), and each spline is made up of one Physical Access Coding Sub-Layer (PCS) block and two TX lanes. So each channel has two PCS blocks and four TX lanes. The TX lanes are used as DP lanes or TMDS data/clock pairs depending on the output type. Additionally the PHY also contains an AUX lane with AUX blocks for each channel. This is used for DP AUX communication, but this fact isn't really relevant for the driver since AUX is controlled from the display controller side. No DPIO registers need to be accessed during AUX communication, Generally the common lane corresponds to the pipe and the spline (PCS/TX) corresponds to the port. For dual channel PHY (VLV/CHV): pipe A == CMN/PLL/REF CH0 pipe B == CMN/PLL/REF CH1 port B == PCS/TX CH0 port C == PCS/TX CH1 This is especially important when we cross the streams ie. drive port B with pipe B, or port C with pipe A. For single channel PHY (CHV): pipe C == CMN/PLL/REF CH0 port D == PCS/TX CH0 Note: digital port B is DDI0, digital port C is DDI1, digital port D is DDI2 CH0 CH1 CMN/PLL/REF CMN/PLL/REF PCS01 PCS23 PCS01 PCS23 TX0 TX1 TX2 TX3 TX0 TX1 TX2 TX3 DDI0 DDI1 CH0 CMN/PLL/REF PCS01 PCS23 TX0 TX1 TX2 TX3 DDI2 This sections covers all things related to the GEM implementation in the i915 driver. Motivation: Certain OpenGL features (e.g. transform feedback, performance monitoring) require userspace code to submit batches containing commands such as MI_LOAD_REGISTER_IMM to access various registers. Unfortunately, some generations of the hardware will noop these commands in unsecure batches (which includes all userspace batches submitted via i915) even though the commands may be safe and represent the intended programming model of the device. The software command parser is similar in operation to the command parsing done in hardware for unsecure batches. However, the software parser allows some operations that would be noop'd by hardware, if the parser determines the operation is safe, and submits the batch as secure to prevent hardware parsing. Threats: At a high level, the hardware (and software) checks attempt to prevent granting userspace undue privileges. There are three categories of privilege. First, commands which are explicitly defined as privileged or which should only be used by the kernel driver. The parser generally rejects such commands, though it may allow some from the drm master process. Second, commands which access registers. To support correct/enhanced userspace functionality, particularly certain OpenGL extensions, the parser provides a whitelist of registers which userspace may safely access (for both normal and drm master processes). Third, commands which access privileged memory (i.e. GGTT, HWS page, etc). The parser always rejects such commands. The majority of the problematic commands fall in the MI_* range, with only a few specific commands on each ring (e.g. PIPE_CONTROL and MI_FLUSH_DW). Implementation: Each ring maintains tables of commands and registers which the parser uses in scanning batch buffers submitted to that ring. Since the set of commands that the parser must check for is significantly smaller than the number of commands supported, the parser tables contain only those commands required by the parser. This generally works because command opcode ranges have standard command length encodings. So for commands that the parser does not need to check, it can easily skip them. This is implemented via a per-ring length decoding vfunc. Unfortunately, there are a number of commands that do not follow the standard length encoding for their opcode range, primarily amongst the MI_* commands. To handle this, the parser provides a way to define explicit skip entries in the per-ring command tables. Other command table entries map fairly directly to high level categories mentioned above: rejected, master-only, register whitelist. The parser implements a number of checks, including the privileged memory checks, via a general bitmasking mechanism. Kernel Hackers Manual July 2017 i915_cmd_parser_init_ring 9 4.1.27 i915_cmd_parser_init_ring set cmd parser related fields for a ringbuffer int i915_cmd_parser_init_ring struct intel_engine_cs * ring ring the ringbuffer to initialize Optionally initializes fields related to batch buffer command parsing in the struct intel_engine_cs based on whether the platform requires software command parsing. non-zero if initialization fails Kernel Hackers Manual July 2017 i915_cmd_parser_fini_ring 9 4.1.27 i915_cmd_parser_fini_ring clean up cmd parser related fields void i915_cmd_parser_fini_ring struct intel_engine_cs * ring ring the ringbuffer to clean up Releases any resources related to command parsing that may have been initialized for the specified ring. Kernel Hackers Manual July 2017 i915_needs_cmd_parser 9 4.1.27 i915_needs_cmd_parser should a given ring use software command parsing? bool i915_needs_cmd_parser struct intel_engine_cs * ring ring the ring in question Only certain platforms require software batch buffer command parsing, and only when enabled via module parameter. true if the ring requires software command parsing Kernel Hackers Manual July 2017 i915_parse_cmds 9 4.1.27 i915_parse_cmds parse a submitted batch buffer for privilege violations int i915_parse_cmds struct intel_engine_cs * ring struct drm_i915_gem_object * batch_obj struct drm_i915_gem_object * shadow_batch_obj u32 batch_start_offset u32 batch_len bool is_master ring the ring on which the batch is to execute batch_obj the batch buffer in question shadow_batch_obj copy of the batch buffer in question batch_start_offset byte offset in the batch at which execution starts batch_len length of the commands in batch_obj is_master is the submitting process the drm master? Parses the specified batch buffer looking for privilege violations as described in the overview. non-zero if the parser finds violations or otherwise fails; -EACCES if the batch appears legal but should use hardware parsing Kernel Hackers Manual July 2017 i915_cmd_parser_get_version 9 4.1.27 i915_cmd_parser_get_version get the cmd parser version number int i915_cmd_parser_get_version void void no arguments The cmd parser maintains a simple increasing integer version number suitable for passing to userspace clients to determine what operations are permitted. the current version number of the cmd parser In order to submit batch buffers as 'secure', the software command parser must ensure that a batch buffer cannot be modified after parsing. It does this by copying the user provided batch buffer contents to a kernel owned buffer from which the hardware will actually execute, and by carefully managing the address space bindings for such buffers. The batch pool framework provides a mechanism for the driver to manage a set of scratch buffers to use for this purpose. The framework can be extended to support other uses cases should they arise. Kernel Hackers Manual July 2017 i915_gem_batch_pool_init 9 4.1.27 i915_gem_batch_pool_init initialize a batch buffer pool void i915_gem_batch_pool_init struct drm_device * dev struct i915_gem_batch_pool * pool dev the drm device pool the batch buffer pool Kernel Hackers Manual July 2017 i915_gem_batch_pool_fini 9 4.1.27 i915_gem_batch_pool_fini clean up a batch buffer pool void i915_gem_batch_pool_fini struct i915_gem_batch_pool * pool pool the pool to clean up Callers must hold the struct_mutex. Kernel Hackers Manual July 2017 i915_gem_batch_pool_get 9 4.1.27 i915_gem_batch_pool_get select a buffer from the pool struct drm_i915_gem_object * i915_gem_batch_pool_get struct i915_gem_batch_pool * pool size_t size pool the batch buffer pool size the minimum desired size of the returned buffer Finds or allocates a batch buffer in the pool with at least the requested size. The caller is responsible for any domain, active/inactive, or purgeability management for the returned buffer. Callers must hold the struct_mutex the selected batch buffer object Motivation: GEN8 brings an expansion of the HW contexts: Logical Ring Contexts. These expanded contexts enable a number of new abilities, especially Execlists (also implemented in this file). One of the main differences with the legacy HW contexts is that logical ring contexts incorporate many more things to the context's state, like PDPs or ringbuffer control registers: The reason why PDPs are included in the context is straightforward: as PPGTTs (per-process GTTs) are actually per-context, having the PDPs contained there mean you don't need to do a ppgtt->switch_mm yourself, instead, the GPU will do it for you on the context switch. But, what about the ringbuffer control registers (head, tail, etc..)? shouldn't we just need a set of those per engine command streamer? This is where the name Logical Rings starts to make sense: by virtualizing the rings, the engine cs shifts to a new ring buffer with every context switch. When you want to submit a workload to the GPU you: A) choose your context, B) find its appropriate virtualized ring, C) write commands to it and then, finally, D) tell the GPU to switch to that context. Instead of the legacy MI_SET_CONTEXT, the way you tell the GPU to switch to a contexts is via a context execution list, ergo Execlists. LRC implementation: Regarding the creation of contexts, we have: - One global default context. - One local default context for each opened fd. - One local extra context for each context create ioctl call. Now that ringbuffers belong per-context (and not per-engine, like before) and that contexts are uniquely tied to a given engine (and not reusable, like before) we need: - One ringbuffer per-engine inside each context. - One backing object per-engine inside each context. The global default context starts its life with these new objects fully allocated and populated. The local default context for each opened fd is more complex, because we don't know at creation time which engine is going to use them. To handle this, we have implemented a deferred creation of LR contexts: The local context starts its life as a hollow or blank holder, that only gets populated for a given engine once we receive an execbuffer. If later on we receive another execbuffer ioctl for the same context but a different engine, we allocate/populate a new ringbuffer and context backing object and so on. Finally, regarding local contexts created using the ioctl call: as they are only allowed with the render ring, we can allocate & populate them right away (no need to defer anything, at least for now). Execlists implementation: Execlists are the new method by which, on gen8+ hardware, workloads are submitted for execution (as opposed to the legacy, ringbuffer-based, method). This method works as follows: When a request is committed, its commands (the BB start and any leading or trailing commands, like the seqno breadcrumbs) are placed in the ringbuffer for the appropriate context. The tail pointer in the hardware context is not updated at this time, but instead, kept by the driver in the ringbuffer structure. A structure representing this request is added to a request queue for the appropriate engine: this structure contains a copy of the context's tail after the request was written to the ring buffer and a pointer to the context itself. If the engine's request queue was empty before the request was added, the queue is processed immediately. Otherwise the queue will be processed during a context switch interrupt. In any case, elements on the queue will get sent (in pairs) to the GPU's ExecLists Submit Port (ELSP, for short) with a globally unique 20-bits submission ID. When execution of a request completes, the GPU updates the context status buffer with a context complete event and generates a context switch interrupt. During the interrupt handling, the driver examines the events in the buffer: for each context complete event, if the announced ID matches that on the head of the request queue, then that request is retired and removed from the queue. After processing, if any requests were retired and the queue is not empty then a new execution list can be submitted. The two requests at the front of the queue are next to be submitted but since a context may not occur twice in an execution list, if subsequent requests have the same ID as the first then the two requests must be combined. This is done simply by discarding requests at the head of the queue until either only one requests is left (in which case we use a NULL second context) or the first two requests have unique IDs. By always executing the first two requests in the queue the driver ensures that the GPU is kept as busy as possible. In the case where a single context completes but a second context is still executing, the request for this second context will be at the head of the queue when we remove the first one. This request will then be resubmitted along with a new request for a different context, which will cause the hardware to continue executing the second request and queue the new request (the GPU detects the condition of a context getting preempted with the same context and optimizes the context switch flow by not doing preemption, but just sampling the new tail pointer). Kernel Hackers Manual July 2017 intel_sanitize_enable_execlists 9 4.1.27 intel_sanitize_enable_execlists sanitize i915.enable_execlists int intel_sanitize_enable_execlists struct drm_device * dev int enable_execlists dev DRM device. enable_execlists value of i915.enable_execlists module parameter. Only certain platforms support Execlists (the prerequisites being support for Logical Ring Contexts and Aliasing PPGTT or better). 1 if Execlists is supported and has to be enabled. Kernel Hackers Manual July 2017 intel_execlists_ctx_id 9 4.1.27 intel_execlists_ctx_id get the Execlists Context ID u32 intel_execlists_ctx_id struct drm_i915_gem_object * ctx_obj ctx_obj Logical Ring Context backing object. Do not confuse with ctx->id! Unfortunately we have a name overload the old context ID we pass to userspace as a handler so that they can refer to a context, and the new context ID we pass to the ELSP so that the GPU can inform us of the context status via interrupts. 20-bits globally unique context ID. Kernel Hackers Manual July 2017 intel_lrc_irq_handler 9 4.1.27 intel_lrc_irq_handler handle Context Switch interrupts void intel_lrc_irq_handler struct intel_engine_cs * ring ring Engine Command Streamer to handle. Check the unread Context Status Buffers and manage the submission of new contexts to the ELSP accordingly. Kernel Hackers Manual July 2017 intel_execlists_submission 9 4.1.27 intel_execlists_submission submit a batchbuffer for execution, Execlists style int intel_execlists_submission struct drm_device * dev struct drm_file * file struct intel_engine_cs * ring struct intel_context * ctx struct drm_i915_gem_execbuffer2 * args struct list_head * vmas struct drm_i915_gem_object * batch_obj u64 exec_start u32 dispatch_flags dev DRM device. file DRM file. ring Engine Command Streamer to submit to. ctx Context to employ for this submission. args execbuffer call arguments. vmas list of vmas. batch_obj the batchbuffer to submit. exec_start batchbuffer start virtual address pointer. dispatch_flags translated execbuffer call flags. This is the evil twin version of i915_gem_ringbuffer_submission. It abstracts away the submission details of the execbuffer ioctl call. non-zero if the submission fails. Kernel Hackers Manual July 2017 intel_logical_ring_begin 9 4.1.27 intel_logical_ring_begin prepare the logical ringbuffer to accept some commands int intel_logical_ring_begin struct intel_ringbuffer * ringbuf struct intel_context * ctx int num_dwords ringbuf Logical ringbuffer. ctx -- undescribed -- num_dwords number of DWORDs that we plan to write to the ringbuffer. The ringbuffer might not be ready to accept the commands right away (maybe it needs to be wrapped, or wait a bit for the tail to be updated). This function takes care of that and also preallocates a request (every workload submission is still mediated through requests, same as it did with legacy ringbuffer submission). non-zero if the ringbuffer is not ready to be written to. Kernel Hackers Manual July 2017 intel_logical_ring_cleanup 9 4.1.27 intel_logical_ring_cleanup deallocate the Engine Command Streamer void intel_logical_ring_cleanup struct intel_engine_cs * ring ring Engine Command Streamer. Kernel Hackers Manual July 2017 intel_logical_rings_init 9 4.1.27 intel_logical_rings_init allocate, populate and init the Engine Command Streamers int intel_logical_rings_init struct drm_device * dev dev DRM device. This function inits the engines for an Execlists submission style (the equivalent in the legacy ringbuffer submission world would be i915_gem_init_rings). It does it only for those engines that are present in the hardware. non-zero if the initialization failed. Kernel Hackers Manual July 2017 intel_lr_context_free 9 4.1.27 intel_lr_context_free free the LRC specific bits of a context void intel_lr_context_free struct intel_context * ctx ctx the LR context to free. this only the per-engine backing objects and the logical ringbuffer. Kernel Hackers Manual July 2017 intel_lr_context_deferred_create 9 4.1.27 intel_lr_context_deferred_create create the LRC specific bits of a context int intel_lr_context_deferred_create struct intel_context * ctx struct intel_engine_cs * ring ctx LR context to create. ring engine to be used with the context. This function can be called more than once, with different engines, if we plan to use the context with them. The context backing objects and the ringbuffers (specially the ringbuffer backing objects) suck a lot of memory up, and that's why it's better to make sure first that we need to use a given ring with the context. non-zero on error. Background and previous state Historically objects could exists (be bound) in global GTT space only as singular instances with a view representing all of the object's backing pages in a linear fashion. This view will be called a normal view. To support multiple views of the same object, where the number of mapped pages is not equal to the backing store, or where the layout of the pages is not linear, concept of a GGTT view was added. One example of an alternative view is a stereo display driven by a single image. In this case we would have a framebuffer looking like this (2x2 pages): 12 34 Above would represent a normal GGTT view as normally mapped for GPU or CPU rendering. In contrast, fed to the display engine would be an alternative view which could look something like this: 1212 3434 In this example both the size and layout of pages in the alternative view is different from the normal view. Implementation and usage GGTT views are implemented using VMAs and are distinguished via enum i915_ggtt_view_type and struct i915_ggtt_view. A new flavour of core GEM functions which work with GGTT bound objects were added with the _ggtt_ infix, and sometimes with _view postfix to avoid renaming in large amounts of code. They take the struct i915_ggtt_view parameter encapsulating all metadata required to implement a view. As a helper for callers which are only interested in the normal view, globally const i915_ggtt_view_normal singleton instance exists. All old core GEM API functions, the ones not taking the view parameter, are operating on, or with the normal GGTT view. Code wanting to add or use a new GGTT view needs to: 1. Add a new enum with a suitable name. 2. Extend the metadata in the i915_ggtt_view structure if required. 3. Add support to i915_get_vma_pages. New views are required to build a scatter-gather table from within the i915_get_vma_pages function. This table is stored in the vma.ggtt_view and exists for the lifetime of an VMA. Core API is designed to have copy semantics which means that passed in struct i915_ggtt_view does not need to be persistent (left around after calling the core API functions). Kernel Hackers Manual July 2017 i915_dma_map_single 9 4.1.27 i915_dma_map_single Create a dma mapping for a page table/dir/etc. i915_dma_map_single px dev px Page table/dir/etc to get a DMA map for dev drm device Page table allocations are unified across all gens. They always require a single 4k allocation, as well as a DMA mapping. If we keep the structs symmetric here, the simple macro covers us for every page table type. 0 if success. Kernel Hackers Manual July 2017 alloc_pt_range 9 4.1.27 alloc_pt_range Allocate a multiple page tables int alloc_pt_range struct i915_page_directory_entry * pd uint16_t pde size_t count struct drm_device * dev pd The page directory which will have at least count entries available to point to the allocated page tables. pde First page directory entry for which we are allocating. count Number of pages to allocate. dev DRM device. Allocates multiple page table pages and sets the appropriate entries in the page table structure within the page directory. Function cleans up after itself on any failures. 0 if allocation succeeded. Kernel Hackers Manual July 2017 i915_vma_bind 9 4.1.27 i915_vma_bind Sets up PTEs for an VMA in it's corresponding address space. int i915_vma_bind struct i915_vma * vma enum i915_cache_level cache_level u32 flags vma VMA to map cache_level mapping cache level flags flags like global or local mapping DMA addresses are taken from the scatter-gather table of this object (or of this VMA in case of non-default GGTT views) and PTE entries set up. Note that DMA addresses are also the only part of the SG table we care about. This section documents the interface functions for evicting buffer objects to make space available in the virtual gpu address spaces. Note that this is mostly orthogonal to shrinking buffer objects caches, which has the goal to make main memory (shared with the gpu through the unified memory architecture) available. Kernel Hackers Manual July 2017 i915_gem_evict_something 9 4.1.27 i915_gem_evict_something Evict vmas to make room for binding a new one int i915_gem_evict_something struct drm_device * dev struct i915_address_space * vm int min_size unsigned alignment unsigned cache_level unsigned long start unsigned long end unsigned flags dev drm_device vm address space to evict from min_size size of the desired free space alignment alignment constraint of the desired free space cache_level cache_level for the desired space start start (inclusive) of the range from which to evict objects end end (exclusive) of the range from which to evict objects flags additional flags to control the eviction algorithm This function will try to evict vmas until a free space satisfying the requirements is found. Callers must check first whether any such hole exists already before calling this function. This function is used by the object/vma binding code. Since this function is only used to free up virtual address space it only ignores pinned vmas, and not object where the backing storage itself is pinned. Hence obj->pages_pin_count does not protect against eviction. This is for freeing up virtual address space, not for freeing memory in e.g. the shrinker. Kernel Hackers Manual July 2017 i915_gem_evict_vm 9 4.1.27 i915_gem_evict_vm Evict all idle vmas from a vm int i915_gem_evict_vm struct i915_address_space * vm bool do_idle vm Address space to cleanse do_idle Boolean directing whether to idle first. This function evicts all idles vmas from a vm. If all unpinned vmas should be evicted the do_idle needs to be set to true. This is used by the execbuf code as a last-ditch effort to defragment the address space. This is for freeing up virtual address space, not for freeing memory in e.g. the shrinker. Kernel Hackers Manual July 2017 i915_gem_evict_everything 9 4.1.27 i915_gem_evict_everything Try to evict all objects int i915_gem_evict_everything struct drm_device * dev dev Device to evict objects for This functions tries to evict all gem objects from all address spaces. Used by the shrinker as a last-ditch effort and for suspend, before releasing the backing storage of all unbound objects. This section documents the interface function for shrinking memory usage of buffer object caches. Shrinking is used to make main memory available. Note that this is mostly orthogonal to evicting buffer objects, which has the goal to make space in gpu virtual address spaces. Kernel Hackers Manual July 2017 i915_gem_shrink 9 4.1.27 i915_gem_shrink Shrink buffer object caches unsigned long i915_gem_shrink struct drm_i915_private * dev_priv long target unsigned flags dev_priv i915 device target amount of memory to make available, in pages flags control flags for selecting cache types This function is the main interface to the shrinker. It will try to release up to target pages of main memory backing storage from buffer objects. Selection of the specific caches can be done with flags. This is e.g. useful when purgeable objects should be removed from caches preferentially. Note that it's not guaranteed that released amount is actually available as free system memory - the pages might still be in-used to due to other reasons (like cpu mmaps) or the mm core has reused them before we could grab them. Therefore code that needs to explicitly shrink buffer objects caches (e.g. to avoid deadlocks in memory reclaim) must fall back to i915_gem_shrink_all. Also note that any kind of pinning (both per-vma address space pins and backing storage pins at the buffer object level) result in the shrinker code having to skip the object. The number of pages of backing storage actually released. Kernel Hackers Manual July 2017 i915_gem_shrink_all 9 4.1.27 i915_gem_shrink_all Shrink buffer object caches completely unsigned long i915_gem_shrink_all struct drm_i915_private * dev_priv dev_priv i915 device This is a simple wraper around i915_gem_shrink to aggressively shrink all caches completely. It also first waits for and retires all outstanding requests to also be able to release backing storage for active objects. This should only be used in code to intentionally quiescent the gpu or as a last-ditch effort when memory seems to have run out. The number of pages of backing storage actually released. Kernel Hackers Manual July 2017 i915_gem_shrinker_init 9 4.1.27 i915_gem_shrinker_init Initialize i915 shrinker void i915_gem_shrinker_init struct drm_i915_private * dev_priv dev_priv i915 device This function registers and sets up the i915 shrinker and OOM handler. This sections covers all things related to the tracepoints implemented in the i915 driver. With full ppgtt enabled each process using drm will allocate at least one translation table. With these traces it is possible to keep track of the allocation and of the lifetime of the tables; this can be used during testing/debug to verify that we are not leaking ppgtts. These traces identify the ppgtt through the vm pointer, which is also printed by the i915_vma_bind and i915_vma_unbind tracepoints. These tracepoints are used to track creation and deletion of contexts. If full ppgtt is enabled, they also print the address of the vm assigned to the context. This tracepoint allows tracking of the mm switch, which is an important point in the lifetime of the vm in the legacy submission path. This tracepoint is called only if full ppgtt is enabled.