VIDIOC_SUBDEV_G_FRAME_INTERVAL, VIDIOC_SUBDEV_S_FRAME_INTERVAL — Get or set the frame interval on a subdev pad
int ioctl( | int fd, |
| int request, | |
struct v4l2_subdev_frame_interval *argp
); |
fdFile descriptor returned by open().
requestVIDIOC_SUBDEV_G_FRAME_INTERVAL, VIDIOC_SUBDEV_S_FRAME_INTERVAL
argpThis is an experimental interface and may change in the future.
These ioctls are used to get and set the frame interval at specific subdev pads in the image pipeline. The frame interval only makes sense for sub-devices that can control the frame period on their own. This includes, for instance, image sensors and TV tuners. Sub-devices that don't support frame intervals must not implement these ioctls.
To retrieve the current frame interval applications set the
pad field of a struct v4l2_subdev_frame_interval to
the desired pad number as reported by the media controller API. When they
call the VIDIOC_SUBDEV_G_FRAME_INTERVAL ioctl with a
pointer to this structure the driver fills the members of the
interval field.
To change the current frame interval applications set both the
pad field and all members of the
interval field. When they call the
VIDIOC_SUBDEV_S_FRAME_INTERVAL ioctl with a pointer to
this structure the driver verifies the requested interval, adjusts it based
on the hardware capabilities and configures the device. Upon return the
struct v4l2_subdev_frame_interval contains the current frame interval as would be
returned by a VIDIOC_SUBDEV_G_FRAME_INTERVAL call.
Drivers must not return an error solely because the requested interval doesn't match the device capabilities. They must instead modify the interval to match what the hardware can provide. The modified interval should be as close as possible to the original request.
Sub-devices that support the frame interval ioctls should implement them on a single pad only. Their behaviour when supported on multiple pads of the same sub-device is not defined.
Table A.108. struct v4l2_subdev_frame_interval
| __u32 | pad | Pad number as reported by the media controller API. |
| struct v4l2_fract | interval | Period, in seconds, between consecutive video frames. |
| __u32 | reserved[9] | Reserved for future extensions. Applications and drivers must set the array to zero. |
On success 0 is returned, on error -1 and the errno variable is set appropriately. The generic error codes are described at the Generic Error Codes chapter.
The frame interval can't be changed because the pad is currently
busy. This can be caused, for instance, by an active video stream on
the pad. The ioctl must not be retried without performing another
action to fix the problem first. Only returned by
VIDIOC_SUBDEV_S_FRAME_INTERVAL
The struct v4l2_subdev_frame_interval pad
references a non-existing pad, or the pad doesn't support frame
intervals.