1 /*
2 * Copyright (c) 2006-2008 Intel Corporation
3 * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
4 *
5 * DRM core CRTC related functions
6 *
7 * Permission to use, copy, modify, distribute, and sell this software and its
8 * documentation for any purpose is hereby granted without fee, provided that
9 * the above copyright notice appear in all copies and that both that copyright
10 * notice and this permission notice appear in supporting documentation, and
11 * that the name of the copyright holders not be used in advertising or
12 * publicity pertaining to distribution of the software without specific,
13 * written prior permission. The copyright holders make no representations
14 * about the suitability of this software for any purpose. It is provided "as
15 * is" without express or implied warranty.
16 *
17 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
18 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
19 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
20 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
21 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
22 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
23 * OF THIS SOFTWARE.
24 *
25 * Authors:
26 * Keith Packard
27 * Eric Anholt <eric@anholt.net>
28 * Dave Airlie <airlied@linux.ie>
29 * Jesse Barnes <jesse.barnes@intel.com>
30 */
31
32 #include <linux/export.h>
33 #include <linux/moduleparam.h>
34
35 #include <drm/drm_client.h>
36 #include <drm/drm_crtc.h>
37 #include <drm/drm_edid.h>
38 #include <drm/drm_fb_helper.h>
39 #include <drm/drm_fourcc.h>
40 #include <drm/drm_modeset_helper_vtables.h>
41 #include <drm/drm_print.h>
42 #include <drm/drm_probe_helper.h>
43 #include <drm/drm_sysfs.h>
44
45 #include "drm_crtc_helper_internal.h"
46
47 /**
48 * DOC: output probing helper overview
49 *
50 * This library provides some helper code for output probing. It provides an
51 * implementation of the core &drm_connector_funcs.fill_modes interface with
52 * drm_helper_probe_single_connector_modes().
53 *
54 * It also provides support for polling connectors with a work item and for
55 * generic hotplug interrupt handling where the driver doesn't or cannot keep
56 * track of a per-connector hpd interrupt.
57 *
58 * This helper library can be used independently of the modeset helper library.
59 * Drivers can also overwrite different parts e.g. use their own hotplug
60 * handling code to avoid probing unrelated outputs.
61 *
62 * The probe helpers share the function table structures with other display
63 * helper libraries. See &struct drm_connector_helper_funcs for the details.
64 */
65
66 static bool drm_kms_helper_poll = true;
67 module_param_named(poll, drm_kms_helper_poll, bool, 0600);
68
69 static enum drm_mode_status
70 drm_mode_validate_flag(const struct drm_display_mode *mode,
71 int flags)
72 {
73 if ((mode->flags & DRM_MODE_FLAG_INTERLACE) &&
74 !(flags & DRM_MODE_FLAG_INTERLACE))
75 return MODE_NO_INTERLACE;
76
77 if ((mode->flags & DRM_MODE_FLAG_DBLSCAN) &&
78 !(flags & DRM_MODE_FLAG_DBLSCAN))
79 return MODE_NO_DBLESCAN;
80
81 if ((mode->flags & DRM_MODE_FLAG_3D_MASK) &&
82 !(flags & DRM_MODE_FLAG_3D_MASK))
83 return MODE_NO_STEREO;
84
85 return MODE_OK;
86 }
87
88 static enum drm_mode_status
89 drm_mode_validate_pipeline(struct drm_display_mode *mode,
90 struct drm_connector *connector)
91 {
92 struct drm_device *dev = connector->dev;
93 enum drm_mode_status ret = MODE_OK;
94 struct drm_encoder *encoder;
95 int i;
96
97 /* Step 1: Validate against connector */
98 ret = drm_connector_mode_valid(connector, mode);
99 if (ret != MODE_OK)
100 return ret;
101
102 /* Step 2: Validate against encoders and crtcs */
103 drm_connector_for_each_possible_encoder(connector, encoder, i) {
104 struct drm_crtc *crtc;
105
106 ret = drm_encoder_mode_valid(encoder, mode);
107 if (ret != MODE_OK) {
108 /* No point in continuing for crtc check as this encoder
109 * will not accept the mode anyway. If all encoders
110 * reject the mode then, at exit, ret will not be
111 * MODE_OK. */
112 continue;
113 }
114
115 ret = drm_bridge_mode_valid(encoder->bridge, mode);
116 if (ret != MODE_OK) {
117 /* There is also no point in continuing for crtc check
118 * here. */
119 continue;
120 }
121
122 drm_for_each_crtc(crtc, dev) {
123 if (!drm_encoder_crtc_ok(encoder, crtc))
124 continue;
125
126 ret = drm_crtc_mode_valid(crtc, mode);
127 if (ret == MODE_OK) {
128 /* If we get to this point there is at least
129 * one combination of encoder+crtc that works
130 * for this mode. Lets return now. */
131 return ret;
132 }
133 }
134 }
135
136 return ret;
137 }
138
139 static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector)
140 {
141 struct drm_cmdline_mode *cmdline_mode;
142 struct drm_display_mode *mode;
143
144 cmdline_mode = &connector->cmdline_mode;
145 if (!cmdline_mode->specified)
146 return 0;
147
148 /* Only add a GTF mode if we find no matching probed modes */
149 list_for_each_entry(mode, &connector->probed_modes, head) {
150 if (mode->hdisplay != cmdline_mode->xres ||
151 mode->vdisplay != cmdline_mode->yres)
152 continue;
153
154 if (cmdline_mode->refresh_specified) {
155 /* The probed mode's vrefresh is set until later */
156 if (drm_mode_vrefresh(mode) != cmdline_mode->refresh)
157 continue;
158 }
159
160 return 0;
161 }
162
163 mode = drm_mode_create_from_cmdline_mode(connector->dev,
164 cmdline_mode);
165 if (mode == NULL)
166 return 0;
167
168 drm_mode_probed_add(connector, mode);
169 return 1;
170 }
171
172 enum drm_mode_status drm_crtc_mode_valid(struct drm_crtc *crtc,
173 const struct drm_display_mode *mode)
174 {
175 const struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
176
177 if (!crtc_funcs || !crtc_funcs->mode_valid)
178 return MODE_OK;
179
180 return crtc_funcs->mode_valid(crtc, mode);
181 }
182
183 enum drm_mode_status drm_encoder_mode_valid(struct drm_encoder *encoder,
184 const struct drm_display_mode *mode)
185 {
186 const struct drm_encoder_helper_funcs *encoder_funcs =
187 encoder->helper_private;
188
189 if (!encoder_funcs || !encoder_funcs->mode_valid)
190 return MODE_OK;
191
192 return encoder_funcs->mode_valid(encoder, mode);
193 }
194
195 enum drm_mode_status drm_connector_mode_valid(struct drm_connector *connector,
196 struct drm_display_mode *mode)
197 {
198 const struct drm_connector_helper_funcs *connector_funcs =
199 connector->helper_private;
200
201 if (!connector_funcs || !connector_funcs->mode_valid)
202 return MODE_OK;
203
204 return connector_funcs->mode_valid(connector, mode);
205 }
206
207 #define DRM_OUTPUT_POLL_PERIOD (10*HZ)
208 /**
209 * drm_kms_helper_poll_enable - re-enable output polling.
210 * @dev: drm_device
211 *
212 * This function re-enables the output polling work, after it has been
213 * temporarily disabled using drm_kms_helper_poll_disable(), for example over
214 * suspend/resume.
215 *
216 * Drivers can call this helper from their device resume implementation. It is
217 * not an error to call this even when output polling isn't enabled.
218 *
219 * Note that calls to enable and disable polling must be strictly ordered, which
220 * is automatically the case when they're only call from suspend/resume
221 * callbacks.
222 */
223 void drm_kms_helper_poll_enable(struct drm_device *dev)
224 {
225 bool poll = false;
226 struct drm_connector *connector;
227 struct drm_connector_list_iter conn_iter;
228 unsigned long delay = DRM_OUTPUT_POLL_PERIOD;
229
230 if (!dev->mode_config.poll_enabled || !drm_kms_helper_poll)
231 return;
232
233 drm_connector_list_iter_begin(dev, &conn_iter);
234 drm_for_each_connector_iter(connector, &conn_iter) {
235 if (connector->polled & (DRM_CONNECTOR_POLL_CONNECT |
236 DRM_CONNECTOR_POLL_DISCONNECT))
237 poll = true;
238 }
239 drm_connector_list_iter_end(&conn_iter);
240
241 if (dev->mode_config.delayed_event) {
242 /*
243 * FIXME:
244 *
245 * Use short (1s) delay to handle the initial delayed event.
246 * This delay should not be needed, but Optimus/nouveau will
247 * fail in a mysterious way if the delayed event is handled as
248 * soon as possible like it is done in
249 * drm_helper_probe_single_connector_modes() in case the poll
250 * was enabled before.
251 */
252 poll = true;
253 delay = HZ;
254 }
255
256 if (poll)
257 schedule_delayed_work(&dev->mode_config.output_poll_work, delay);
258 }
259 EXPORT_SYMBOL(drm_kms_helper_poll_enable);
260
261 static enum drm_connector_status
262 drm_helper_probe_detect_ctx(struct drm_connector *connector, bool force)
263 {
264 const struct drm_connector_helper_funcs *funcs = connector->helper_private;
265 struct drm_modeset_acquire_ctx ctx;
266 int ret;
267
268 drm_modeset_acquire_init(&ctx, 0);
269
270 retry:
271 ret = drm_modeset_lock(&connector->dev->mode_config.connection_mutex, &ctx);
272 if (!ret) {
273 if (funcs->detect_ctx)
274 ret = funcs->detect_ctx(connector, &ctx, force);
275 else if (connector->funcs->detect)
276 ret = connector->funcs->detect(connector, force);
277 else
278 ret = connector_status_connected;
279 }
280
281 if (ret == -EDEADLK) {
282 drm_modeset_backoff(&ctx);
283 goto retry;
284 }
285
286 if (WARN_ON(ret < 0))
287 ret = connector_status_unknown;
288
289 drm_modeset_drop_locks(&ctx);
290 drm_modeset_acquire_fini(&ctx);
291
292 return ret;
293 }
294
295 /**
296 * drm_helper_probe_detect - probe connector status
297 * @connector: connector to probe
298 * @ctx: acquire_ctx, or NULL to let this function handle locking.
299 * @force: Whether destructive probe operations should be performed.
300 *
301 * This function calls the detect callbacks of the connector.
302 * This function returns &drm_connector_status, or
303 * if @ctx is set, it might also return -EDEADLK.
304 */
305 int
306 drm_helper_probe_detect(struct drm_connector *connector,
307 struct drm_modeset_acquire_ctx *ctx,
308 bool force)
309 {
310 const struct drm_connector_helper_funcs *funcs = connector->helper_private;
311 struct drm_device *dev = connector->dev;
312 int ret;
313
314 if (!ctx)
315 return drm_helper_probe_detect_ctx(connector, force);
316
317 ret = drm_modeset_lock(&dev->mode_config.connection_mutex, ctx);
318 if (ret)
319 return ret;
320
321 if (funcs->detect_ctx)
322 return funcs->detect_ctx(connector, ctx, force);
323 else if (connector->funcs->detect)
324 return connector->funcs->detect(connector, force);
325 else
326 return connector_status_connected;
327 }
328 EXPORT_SYMBOL(drm_helper_probe_detect);
329
330 /**
331 * drm_helper_probe_single_connector_modes - get complete set of display modes
332 * @connector: connector to probe
333 * @maxX: max width for modes
334 * @maxY: max height for modes
335 *
336 * Based on the helper callbacks implemented by @connector in struct
337 * &drm_connector_helper_funcs try to detect all valid modes. Modes will first
338 * be added to the connector's probed_modes list, then culled (based on validity
339 * and the @maxX, @maxY parameters) and put into the normal modes list.
340 *
341 * Intended to be used as a generic implementation of the
342 * &drm_connector_funcs.fill_modes() vfunc for drivers that use the CRTC helpers
343 * for output mode filtering and detection.
344 *
345 * The basic procedure is as follows
346 *
347 * 1. All modes currently on the connector's modes list are marked as stale
348 *
349 * 2. New modes are added to the connector's probed_modes list with
350 * drm_mode_probed_add(). New modes start their life with status as OK.
351 * Modes are added from a single source using the following priority order.
352 *
353 * - &drm_connector_helper_funcs.get_modes vfunc
354 * - if the connector status is connector_status_connected, standard
355 * VESA DMT modes up to 1024x768 are automatically added
356 * (drm_add_modes_noedid())
357 *
358 * Finally modes specified via the kernel command line (video=...) are
359 * added in addition to what the earlier probes produced
360 * (drm_helper_probe_add_cmdline_mode()). These modes are generated
361 * using the VESA GTF/CVT formulas.
362 *
363 * 3. Modes are moved from the probed_modes list to the modes list. Potential
364 * duplicates are merged together (see drm_connector_list_update()).
365 * After this step the probed_modes list will be empty again.
366 *
367 * 4. Any non-stale mode on the modes list then undergoes validation
368 *
369 * - drm_mode_validate_basic() performs basic sanity checks
370 * - drm_mode_validate_size() filters out modes larger than @maxX and @maxY
371 * (if specified)
372 * - drm_mode_validate_flag() checks the modes against basic connector
373 * capabilities (interlace_allowed,doublescan_allowed,stereo_allowed)
374 * - the optional &drm_connector_helper_funcs.mode_valid helper can perform
375 * driver and/or sink specific checks
376 * - the optional &drm_crtc_helper_funcs.mode_valid,
377 * &drm_bridge_funcs.mode_valid and &drm_encoder_helper_funcs.mode_valid
378 * helpers can perform driver and/or source specific checks which are also
379 * enforced by the modeset/atomic helpers
380 *
381 * 5. Any mode whose status is not OK is pruned from the connector's modes list,
382 * accompanied by a debug message indicating the reason for the mode's
383 * rejection (see drm_mode_prune_invalid()).
384 *
385 * Returns:
386 * The number of modes found on @connector.
387 */
388 int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
389 uint32_t maxX, uint32_t maxY)
390 {
391 struct drm_device *dev = connector->dev;
392 struct drm_display_mode *mode;
393 const struct drm_connector_helper_funcs *connector_funcs =
394 connector->helper_private;
395 int count = 0, ret;
396 int mode_flags = 0;
397 bool verbose_prune = true;
398 enum drm_connector_status old_status;
399 struct drm_modeset_acquire_ctx ctx;
400
401 WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
402
403 drm_modeset_acquire_init(&ctx, 0);
404
405 DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id,
406 connector->name);
407
408 retry:
409 ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
410 if (ret == -EDEADLK) {
411 drm_modeset_backoff(&ctx);
412 goto retry;
413 } else
414 WARN_ON(ret < 0);
415
416 /* set all old modes to the stale state */
417 list_for_each_entry(mode, &connector->modes, head)
418 mode->status = MODE_STALE;
419
420 old_status = connector->status;
421
422 if (connector->force) {
423 if (connector->force == DRM_FORCE_ON ||
424 connector->force == DRM_FORCE_ON_DIGITAL)
425 connector->status = connector_status_connected;
426 else
427 connector->status = connector_status_disconnected;
428 if (connector->funcs->force)
429 connector->funcs->force(connector);
430 } else {
431 ret = drm_helper_probe_detect(connector, &ctx, true);
432
433 if (ret == -EDEADLK) {
434 drm_modeset_backoff(&ctx);
435 goto retry;
436 } else if (WARN(ret < 0, "Invalid return value %i for connector detection\n", ret))
437 ret = connector_status_unknown;
438
439 connector->status = ret;
440 }
441
442 /*
443 * Normally either the driver's hpd code or the poll loop should
444 * pick up any changes and fire the hotplug event. But if
445 * userspace sneaks in a probe, we might miss a change. Hence
446 * check here, and if anything changed start the hotplug code.
447 */
448 if (old_status != connector->status) {
449 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
450 connector->base.id,
451 connector->name,
452 drm_get_connector_status_name(old_status),
453 drm_get_connector_status_name(connector->status));
454
455 /*
456 * The hotplug event code might call into the fb
457 * helpers, and so expects that we do not hold any
458 * locks. Fire up the poll struct instead, it will
459 * disable itself again.
460 */
461 dev->mode_config.delayed_event = true;
462 if (dev->mode_config.poll_enabled)
463 schedule_delayed_work(&dev->mode_config.output_poll_work,
464 0);
465 }
466
467 /* Re-enable polling in case the global poll config changed. */
468 if (drm_kms_helper_poll != dev->mode_config.poll_running)
469 drm_kms_helper_poll_enable(dev);
470
471 dev->mode_config.poll_running = drm_kms_helper_poll;
472
473 if (connector->status == connector_status_disconnected) {
474 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n",
475 connector->base.id, connector->name);
476 drm_connector_update_edid_property(connector, NULL);
477 verbose_prune = false;
478 goto prune;
479 }
480
481 count = (*connector_funcs->get_modes)(connector);
482
483 /*
484 * Fallback for when DDC probe failed in drm_get_edid() and thus skipped
485 * override/firmware EDID.
486 */
487 if (count == 0 && connector->status == connector_status_connected)
488 count = drm_add_override_edid_modes(connector);
489
490 if (count == 0 && connector->status == connector_status_connected)
491 count = drm_add_modes_noedid(connector, 1024, 768);
492 count += drm_helper_probe_add_cmdline_mode(connector);
493 if (count == 0)
494 goto prune;
495
496 drm_connector_list_update(connector);
497
498 if (connector->interlace_allowed)
499 mode_flags |= DRM_MODE_FLAG_INTERLACE;
500 if (connector->doublescan_allowed)
501 mode_flags |= DRM_MODE_FLAG_DBLSCAN;
502 if (connector->stereo_allowed)
503 mode_flags |= DRM_MODE_FLAG_3D_MASK;
504
505 list_for_each_entry(mode, &connector->modes, head) {
506 if (mode->status == MODE_OK)
507 mode->status = drm_mode_validate_driver(dev, mode);
508
509 if (mode->status == MODE_OK)
510 mode->status = drm_mode_validate_size(mode, maxX, maxY);
511
512 if (mode->status == MODE_OK)
513 mode->status = drm_mode_validate_flag(mode, mode_flags);
514
515 if (mode->status == MODE_OK)
516 mode->status = drm_mode_validate_pipeline(mode,
517 connector);
518
519 if (mode->status == MODE_OK)
520 mode->status = drm_mode_validate_ycbcr420(mode,
521 connector);
522 }
523
524 prune:
525 drm_mode_prune_invalid(dev, &connector->modes, verbose_prune);
526
527 drm_modeset_drop_locks(&ctx);
528 drm_modeset_acquire_fini(&ctx);
529
530 if (list_empty(&connector->modes))
531 return 0;
532
533 list_for_each_entry(mode, &connector->modes, head)
534 mode->vrefresh = drm_mode_vrefresh(mode);
535
536 drm_mode_sort(&connector->modes);
537
538 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] probed modes :\n", connector->base.id,
539 connector->name);
540 list_for_each_entry(mode, &connector->modes, head) {
541 drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
542 drm_mode_debug_printmodeline(mode);
543 }
544
545 return count;
546 }
547 EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);
548
549 /**
550 * drm_kms_helper_hotplug_event - fire off KMS hotplug events
551 * @dev: drm_device whose connector state changed
552 *
553 * This function fires off the uevent for userspace and also calls the
554 * output_poll_changed function, which is most commonly used to inform the fbdev
555 * emulation code and allow it to update the fbcon output configuration.
556 *
557 * Drivers should call this from their hotplug handling code when a change is
558 * detected. Note that this function does not do any output detection of its
559 * own, like drm_helper_hpd_irq_event() does - this is assumed to be done by the
560 * driver already.
561 *
562 * This function must be called from process context with no mode
563 * setting locks held.
564 */
565 void drm_kms_helper_hotplug_event(struct drm_device *dev)
566 {
567 /* send a uevent + call fbdev */
568 drm_sysfs_hotplug_event(dev);
569 if (dev->mode_config.funcs->output_poll_changed)
570 dev->mode_config.funcs->output_poll_changed(dev);
571
572 drm_client_dev_hotplug(dev);
573 }
574 EXPORT_SYMBOL(drm_kms_helper_hotplug_event);
575
576 static void output_poll_execute(struct work_struct *work)
577 {
578 struct delayed_work *delayed_work = to_delayed_work(work);
579 struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_work);
580 struct drm_connector *connector;
581 struct drm_connector_list_iter conn_iter;
582 enum drm_connector_status old_status;
583 bool repoll = false, changed;
584
585 if (!dev->mode_config.poll_enabled)
586 return;
587
588 /* Pick up any changes detected by the probe functions. */
589 changed = dev->mode_config.delayed_event;
590 dev->mode_config.delayed_event = false;
591
592 if (!drm_kms_helper_poll)
593 goto out;
594
595 if (!mutex_trylock(&dev->mode_config.mutex)) {
596 repoll = true;
597 goto out;
598 }
599
600 drm_connector_list_iter_begin(dev, &conn_iter);
601 drm_for_each_connector_iter(connector, &conn_iter) {
602 /* Ignore forced connectors. */
603 if (connector->force)
604 continue;
605
606 /* Ignore HPD capable connectors and connectors where we don't
607 * want any hotplug detection at all for polling. */
608 if (!connector->polled || connector->polled == DRM_CONNECTOR_POLL_HPD)
609 continue;
610
611 old_status = connector->status;
612 /* if we are connected and don't want to poll for disconnect
613 skip it */
614 if (old_status == connector_status_connected &&
615 !(connector->polled & DRM_CONNECTOR_POLL_DISCONNECT))
616 continue;
617
618 repoll = true;
619
620 connector->status = drm_helper_probe_detect(connector, NULL, false);
621 if (old_status != connector->status) {
622 const char *old, *new;
623
624 /*
625 * The poll work sets force=false when calling detect so
626 * that drivers can avoid to do disruptive tests (e.g.
627 * when load detect cycles could cause flickering on
628 * other, running displays). This bears the risk that we
629 * flip-flop between unknown here in the poll work and
630 * the real state when userspace forces a full detect
631 * call after receiving a hotplug event due to this
632 * change.
633 *
634 * Hence clamp an unknown detect status to the old
635 * value.
636 */
637 if (connector->status == connector_status_unknown) {
638 connector->status = old_status;
639 continue;
640 }
641
642 old = drm_get_connector_status_name(old_status);
643 new = drm_get_connector_status_name(connector->status);
644
645 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] "
646 "status updated from %s to %s\n",
647 connector->base.id,
648 connector->name,
649 old, new);
650
651 changed = true;
652 }
653 }
654 drm_connector_list_iter_end(&conn_iter);
655
656 mutex_unlock(&dev->mode_config.mutex);
657
658 out:
659 if (changed)
660 drm_kms_helper_hotplug_event(dev);
661
662 if (repoll)
663 schedule_delayed_work(delayed_work, DRM_OUTPUT_POLL_PERIOD);
664 }
665
666 /**
667 * drm_kms_helper_is_poll_worker - is %current task an output poll worker?
668 *
669 * Determine if %current task is an output poll worker. This can be used
670 * to select distinct code paths for output polling versus other contexts.
671 *
672 * One use case is to avoid a deadlock between the output poll worker and
673 * the autosuspend worker wherein the latter waits for polling to finish
674 * upon calling drm_kms_helper_poll_disable(), while the former waits for
675 * runtime suspend to finish upon calling pm_runtime_get_sync() in a
676 * connector ->detect hook.
677 */
678 bool drm_kms_helper_is_poll_worker(void)
679 {
680 struct work_struct *work = current_work();
681
682 return work && work->func == output_poll_execute;
683 }
684 EXPORT_SYMBOL(drm_kms_helper_is_poll_worker);
685
686 /**
687 * drm_kms_helper_poll_disable - disable output polling
688 * @dev: drm_device
689 *
690 * This function disables the output polling work.
691 *
692 * Drivers can call this helper from their device suspend implementation. It is
693 * not an error to call this even when output polling isn't enabled or already
694 * disabled. Polling is re-enabled by calling drm_kms_helper_poll_enable().
695 *
696 * Note that calls to enable and disable polling must be strictly ordered, which
697 * is automatically the case when they're only call from suspend/resume
698 * callbacks.
699 */
700 void drm_kms_helper_poll_disable(struct drm_device *dev)
701 {
702 if (!dev->mode_config.poll_enabled)
703 return;
704 cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
705 }
706 EXPORT_SYMBOL(drm_kms_helper_poll_disable);
707
708 /**
709 * drm_kms_helper_poll_init - initialize and enable output polling
710 * @dev: drm_device
711 *
712 * This function intializes and then also enables output polling support for
713 * @dev. Drivers which do not have reliable hotplug support in hardware can use
714 * this helper infrastructure to regularly poll such connectors for changes in
715 * their connection state.
716 *
717 * Drivers can control which connectors are polled by setting the
718 * DRM_CONNECTOR_POLL_CONNECT and DRM_CONNECTOR_POLL_DISCONNECT flags. On
719 * connectors where probing live outputs can result in visual distortion drivers
720 * should not set the DRM_CONNECTOR_POLL_DISCONNECT flag to avoid this.
721 * Connectors which have no flag or only DRM_CONNECTOR_POLL_HPD set are
722 * completely ignored by the polling logic.
723 *
724 * Note that a connector can be both polled and probed from the hotplug handler,
725 * in case the hotplug interrupt is known to be unreliable.
726 */
727 void drm_kms_helper_poll_init(struct drm_device *dev)
728 {
729 INIT_DELAYED_WORK(&dev->mode_config.output_poll_work, output_poll_execute);
730 dev->mode_config.poll_enabled = true;
731
732 drm_kms_helper_poll_enable(dev);
733 }
734 EXPORT_SYMBOL(drm_kms_helper_poll_init);
735
736 /**
737 * drm_kms_helper_poll_fini - disable output polling and clean it up
738 * @dev: drm_device
739 */
740 void drm_kms_helper_poll_fini(struct drm_device *dev)
741 {
742 if (!dev->mode_config.poll_enabled)
743 return;
744
745 dev->mode_config.poll_enabled = false;
746 cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
747 }
748 EXPORT_SYMBOL(drm_kms_helper_poll_fini);
749
750 /**
751 * drm_helper_hpd_irq_event - hotplug processing
752 * @dev: drm_device
753 *
754 * Drivers can use this helper function to run a detect cycle on all connectors
755 * which have the DRM_CONNECTOR_POLL_HPD flag set in their &polled member. All
756 * other connectors are ignored, which is useful to avoid reprobing fixed
757 * panels.
758 *
759 * This helper function is useful for drivers which can't or don't track hotplug
760 * interrupts for each connector.
761 *
762 * Drivers which support hotplug interrupts for each connector individually and
763 * which have a more fine-grained detect logic should bypass this code and
764 * directly call drm_kms_helper_hotplug_event() in case the connector state
765 * changed.
766 *
767 * This function must be called from process context with no mode
768 * setting locks held.
769 *
770 * Note that a connector can be both polled and probed from the hotplug handler,
771 * in case the hotplug interrupt is known to be unreliable.
772 */
773 bool drm_helper_hpd_irq_event(struct drm_device *dev)
774 {
775 struct drm_connector *connector;
776 struct drm_connector_list_iter conn_iter;
777 enum drm_connector_status old_status;
778 bool changed = false;
779
780 if (!dev->mode_config.poll_enabled)
781 return false;
782
783 mutex_lock(&dev->mode_config.mutex);
784 drm_connector_list_iter_begin(dev, &conn_iter);
785 drm_for_each_connector_iter(connector, &conn_iter) {
786 /* Only handle HPD capable connectors. */
787 if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
788 continue;
789
790 old_status = connector->status;
791
792 connector->status = drm_helper_probe_detect(connector, NULL, false);
793 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
794 connector->base.id,
795 connector->name,
796 drm_get_connector_status_name(old_status),
797 drm_get_connector_status_name(connector->status));
798 if (old_status != connector->status)
799 changed = true;
800 }
801 drm_connector_list_iter_end(&conn_iter);
802 mutex_unlock(&dev->mode_config.mutex);
803
804 if (changed)
805 drm_kms_helper_hotplug_event(dev);
806
807 return changed;
808 }
809 EXPORT_SYMBOL(drm_helper_hpd_irq_event);