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/drmP.h>
36 #include <drm/drm_crtc.h>
37 #include <drm/drm_fourcc.h>
38 #include <drm/drm_crtc_helper.h>
39 #include <drm/drm_fb_helper.h>
40 #include <drm/drm_edid.h>
41 
42 /**
43  * DOC: output probing helper overview
44  *
45  * This library provides some helper code for output probing. It provides an
46  * implementation of the core &drm_connector_funcs.fill_modes interface with
47  * drm_helper_probe_single_connector_modes().
48  *
49  * It also provides support for polling connectors with a work item and for
50  * generic hotplug interrupt handling where the driver doesn't or cannot keep
51  * track of a per-connector hpd interrupt.
52  *
53  * This helper library can be used independently of the modeset helper library.
54  * Drivers can also overwrite different parts e.g. use their own hotplug
55  * handling code to avoid probing unrelated outputs.
56  *
57  * The probe helpers share the function table structures with other display
58  * helper libraries. See &struct drm_connector_helper_funcs for the details.
59  */
60 
61 static bool drm_kms_helper_poll = true;
62 module_param_named(poll, drm_kms_helper_poll, bool, 0600);
63 
64 static enum drm_mode_status
65 drm_mode_validate_flag(const struct drm_display_mode *mode,
66 		       int flags)
67 {
68 	if ((mode->flags & DRM_MODE_FLAG_INTERLACE) &&
69 	    !(flags & DRM_MODE_FLAG_INTERLACE))
70 		return MODE_NO_INTERLACE;
71 
72 	if ((mode->flags & DRM_MODE_FLAG_DBLSCAN) &&
73 	    !(flags & DRM_MODE_FLAG_DBLSCAN))
74 		return MODE_NO_DBLESCAN;
75 
76 	if ((mode->flags & DRM_MODE_FLAG_3D_MASK) &&
77 	    !(flags & DRM_MODE_FLAG_3D_MASK))
78 		return MODE_NO_STEREO;
79 
80 	return MODE_OK;
81 }
82 
83 static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector)
84 {
85 	struct drm_cmdline_mode *cmdline_mode;
86 	struct drm_display_mode *mode;
87 
88 	cmdline_mode = &connector->cmdline_mode;
89 	if (!cmdline_mode->specified)
90 		return 0;
91 
92 	/* Only add a GTF mode if we find no matching probed modes */
93 	list_for_each_entry(mode, &connector->probed_modes, head) {
94 		if (mode->hdisplay != cmdline_mode->xres ||
95 		    mode->vdisplay != cmdline_mode->yres)
96 			continue;
97 
98 		if (cmdline_mode->refresh_specified) {
99 			/* The probed mode's vrefresh is set until later */
100 			if (drm_mode_vrefresh(mode) != cmdline_mode->refresh)
101 				continue;
102 		}
103 
104 		return 0;
105 	}
106 
107 	mode = drm_mode_create_from_cmdline_mode(connector->dev,
108 						 cmdline_mode);
109 	if (mode == NULL)
110 		return 0;
111 
112 	drm_mode_probed_add(connector, mode);
113 	return 1;
114 }
115 
116 #define DRM_OUTPUT_POLL_PERIOD (10*HZ)
117 /**
118  * drm_kms_helper_poll_enable - re-enable output polling.
119  * @dev: drm_device
120  *
121  * This function re-enables the output polling work, after it has been
122  * temporarily disabled using drm_kms_helper_poll_disable(), for example over
123  * suspend/resume.
124  *
125  * Drivers can call this helper from their device resume implementation. It is
126  * an error to call this when the output polling support has not yet been set
127  * up.
128  *
129  * Note that calls to enable and disable polling must be strictly ordered, which
130  * is automatically the case when they're only call from suspend/resume
131  * callbacks.
132  */
133 void drm_kms_helper_poll_enable(struct drm_device *dev)
134 {
135 	bool poll = false;
136 	struct drm_connector *connector;
137 	struct drm_connector_list_iter conn_iter;
138 	unsigned long delay = DRM_OUTPUT_POLL_PERIOD;
139 
140 	if (!dev->mode_config.poll_enabled || !drm_kms_helper_poll)
141 		return;
142 
143 	drm_connector_list_iter_begin(dev, &conn_iter);
144 	drm_for_each_connector_iter(connector, &conn_iter) {
145 		if (connector->polled & (DRM_CONNECTOR_POLL_CONNECT |
146 					 DRM_CONNECTOR_POLL_DISCONNECT))
147 			poll = true;
148 	}
149 	drm_connector_list_iter_end(&conn_iter);
150 
151 	if (dev->mode_config.delayed_event) {
152 		/*
153 		 * FIXME:
154 		 *
155 		 * Use short (1s) delay to handle the initial delayed event.
156 		 * This delay should not be needed, but Optimus/nouveau will
157 		 * fail in a mysterious way if the delayed event is handled as
158 		 * soon as possible like it is done in
159 		 * drm_helper_probe_single_connector_modes() in case the poll
160 		 * was enabled before.
161 		 */
162 		poll = true;
163 		delay = HZ;
164 	}
165 
166 	if (poll)
167 		schedule_delayed_work(&dev->mode_config.output_poll_work, delay);
168 }
169 EXPORT_SYMBOL(drm_kms_helper_poll_enable);
170 
171 static enum drm_connector_status
172 drm_helper_probe_detect_ctx(struct drm_connector *connector, bool force)
173 {
174 	const struct drm_connector_helper_funcs *funcs = connector->helper_private;
175 	struct drm_modeset_acquire_ctx ctx;
176 	int ret;
177 
178 	drm_modeset_acquire_init(&ctx, 0);
179 
180 retry:
181 	ret = drm_modeset_lock(&connector->dev->mode_config.connection_mutex, &ctx);
182 	if (!ret) {
183 		if (funcs->detect_ctx)
184 			ret = funcs->detect_ctx(connector, &ctx, force);
185 		else if (connector->funcs->detect)
186 			ret = connector->funcs->detect(connector, force);
187 		else
188 			ret = connector_status_connected;
189 	}
190 
191 	if (ret == -EDEADLK) {
192 		drm_modeset_backoff(&ctx);
193 		goto retry;
194 	}
195 
196 	if (WARN_ON(ret < 0))
197 		ret = connector_status_unknown;
198 
199 	drm_modeset_drop_locks(&ctx);
200 	drm_modeset_acquire_fini(&ctx);
201 
202 	return ret;
203 }
204 
205 /**
206  * drm_helper_probe_detect - probe connector status
207  * @connector: connector to probe
208  * @ctx: acquire_ctx, or NULL to let this function handle locking.
209  * @force: Whether destructive probe operations should be performed.
210  *
211  * This function calls the detect callbacks of the connector.
212  * This function returns &drm_connector_status, or
213  * if @ctx is set, it might also return -EDEADLK.
214  */
215 int
216 drm_helper_probe_detect(struct drm_connector *connector,
217 			struct drm_modeset_acquire_ctx *ctx,
218 			bool force)
219 {
220 	const struct drm_connector_helper_funcs *funcs = connector->helper_private;
221 	struct drm_device *dev = connector->dev;
222 	int ret;
223 
224 	if (!ctx)
225 		return drm_helper_probe_detect_ctx(connector, force);
226 
227 	ret = drm_modeset_lock(&dev->mode_config.connection_mutex, ctx);
228 	if (ret)
229 		return ret;
230 
231 	if (funcs->detect_ctx)
232 		return funcs->detect_ctx(connector, ctx, force);
233 	else if (connector->funcs->detect)
234 		return connector->funcs->detect(connector, force);
235 	else
236 		return connector_status_connected;
237 }
238 EXPORT_SYMBOL(drm_helper_probe_detect);
239 
240 /**
241  * drm_helper_probe_single_connector_modes - get complete set of display modes
242  * @connector: connector to probe
243  * @maxX: max width for modes
244  * @maxY: max height for modes
245  *
246  * Based on the helper callbacks implemented by @connector in struct
247  * &drm_connector_helper_funcs try to detect all valid modes.  Modes will first
248  * be added to the connector's probed_modes list, then culled (based on validity
249  * and the @maxX, @maxY parameters) and put into the normal modes list.
250  *
251  * Intended to be used as a generic implementation of the
252  * &drm_connector_funcs.fill_modes() vfunc for drivers that use the CRTC helpers
253  * for output mode filtering and detection.
254  *
255  * The basic procedure is as follows
256  *
257  * 1. All modes currently on the connector's modes list are marked as stale
258  *
259  * 2. New modes are added to the connector's probed_modes list with
260  *    drm_mode_probed_add(). New modes start their life with status as OK.
261  *    Modes are added from a single source using the following priority order.
262  *
263  *    - debugfs 'override_edid' (used for testing only)
264  *    - firmware EDID (drm_load_edid_firmware())
265  *    - &drm_connector_helper_funcs.get_modes vfunc
266  *    - if the connector status is connector_status_connected, standard
267  *      VESA DMT modes up to 1024x768 are automatically added
268  *      (drm_add_modes_noedid())
269  *
270  *    Finally modes specified via the kernel command line (video=...) are
271  *    added in addition to what the earlier probes produced
272  *    (drm_helper_probe_add_cmdline_mode()). These modes are generated
273  *    using the VESA GTF/CVT formulas.
274  *
275  * 3. Modes are moved from the probed_modes list to the modes list. Potential
276  *    duplicates are merged together (see drm_mode_connector_list_update()).
277  *    After this step the probed_modes list will be empty again.
278  *
279  * 4. Any non-stale mode on the modes list then undergoes validation
280  *
281  *    - drm_mode_validate_basic() performs basic sanity checks
282  *    - drm_mode_validate_size() filters out modes larger than @maxX and @maxY
283  *      (if specified)
284  *    - drm_mode_validate_flag() checks the modes against basic connector
285  *      capabilities (interlace_allowed,doublescan_allowed,stereo_allowed)
286  *    - the optional &drm_connector_helper_funcs.mode_valid helper can perform
287  *      driver and/or hardware specific checks
288  *
289  * 5. Any mode whose status is not OK is pruned from the connector's modes list,
290  *    accompanied by a debug message indicating the reason for the mode's
291  *    rejection (see drm_mode_prune_invalid()).
292  *
293  * Returns:
294  * The number of modes found on @connector.
295  */
296 int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
297 					    uint32_t maxX, uint32_t maxY)
298 {
299 	struct drm_device *dev = connector->dev;
300 	struct drm_display_mode *mode;
301 	const struct drm_connector_helper_funcs *connector_funcs =
302 		connector->helper_private;
303 	int count = 0, ret;
304 	int mode_flags = 0;
305 	bool verbose_prune = true;
306 	enum drm_connector_status old_status;
307 	struct drm_modeset_acquire_ctx ctx;
308 
309 	WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
310 
311 	drm_modeset_acquire_init(&ctx, 0);
312 
313 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id,
314 			connector->name);
315 
316 retry:
317 	ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
318 	if (ret == -EDEADLK) {
319 		drm_modeset_backoff(&ctx);
320 		goto retry;
321 	} else
322 		WARN_ON(ret < 0);
323 
324 	/* set all old modes to the stale state */
325 	list_for_each_entry(mode, &connector->modes, head)
326 		mode->status = MODE_STALE;
327 
328 	old_status = connector->status;
329 
330 	if (connector->force) {
331 		if (connector->force == DRM_FORCE_ON ||
332 		    connector->force == DRM_FORCE_ON_DIGITAL)
333 			connector->status = connector_status_connected;
334 		else
335 			connector->status = connector_status_disconnected;
336 		if (connector->funcs->force)
337 			connector->funcs->force(connector);
338 	} else {
339 		ret = drm_helper_probe_detect(connector, &ctx, true);
340 
341 		if (ret == -EDEADLK) {
342 			drm_modeset_backoff(&ctx);
343 			goto retry;
344 		} else if (WARN(ret < 0, "Invalid return value %i for connector detection\n", ret))
345 			ret = connector_status_unknown;
346 
347 		connector->status = ret;
348 	}
349 
350 	/*
351 	 * Normally either the driver's hpd code or the poll loop should
352 	 * pick up any changes and fire the hotplug event. But if
353 	 * userspace sneaks in a probe, we might miss a change. Hence
354 	 * check here, and if anything changed start the hotplug code.
355 	 */
356 	if (old_status != connector->status) {
357 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
358 			      connector->base.id,
359 			      connector->name,
360 			      drm_get_connector_status_name(old_status),
361 			      drm_get_connector_status_name(connector->status));
362 
363 		/*
364 		 * The hotplug event code might call into the fb
365 		 * helpers, and so expects that we do not hold any
366 		 * locks. Fire up the poll struct instead, it will
367 		 * disable itself again.
368 		 */
369 		dev->mode_config.delayed_event = true;
370 		if (dev->mode_config.poll_enabled)
371 			schedule_delayed_work(&dev->mode_config.output_poll_work,
372 					      0);
373 	}
374 
375 	/* Re-enable polling in case the global poll config changed. */
376 	if (drm_kms_helper_poll != dev->mode_config.poll_running)
377 		drm_kms_helper_poll_enable(dev);
378 
379 	dev->mode_config.poll_running = drm_kms_helper_poll;
380 
381 	if (connector->status == connector_status_disconnected) {
382 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n",
383 			connector->base.id, connector->name);
384 		drm_mode_connector_update_edid_property(connector, NULL);
385 		verbose_prune = false;
386 		goto prune;
387 	}
388 
389 	if (connector->override_edid) {
390 		struct edid *edid = (struct edid *) connector->edid_blob_ptr->data;
391 
392 		count = drm_add_edid_modes(connector, edid);
393 		drm_edid_to_eld(connector, edid);
394 	} else {
395 		struct edid *edid = drm_load_edid_firmware(connector);
396 		if (!IS_ERR_OR_NULL(edid)) {
397 			drm_mode_connector_update_edid_property(connector, edid);
398 			count = drm_add_edid_modes(connector, edid);
399 			drm_edid_to_eld(connector, edid);
400 			kfree(edid);
401 		}
402 		if (count == 0)
403 			count = (*connector_funcs->get_modes)(connector);
404 	}
405 
406 	if (count == 0 && connector->status == connector_status_connected)
407 		count = drm_add_modes_noedid(connector, 1024, 768);
408 	count += drm_helper_probe_add_cmdline_mode(connector);
409 	if (count == 0)
410 		goto prune;
411 
412 	drm_mode_connector_list_update(connector);
413 
414 	if (connector->interlace_allowed)
415 		mode_flags |= DRM_MODE_FLAG_INTERLACE;
416 	if (connector->doublescan_allowed)
417 		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
418 	if (connector->stereo_allowed)
419 		mode_flags |= DRM_MODE_FLAG_3D_MASK;
420 
421 	list_for_each_entry(mode, &connector->modes, head) {
422 		if (mode->status == MODE_OK)
423 			mode->status = drm_mode_validate_basic(mode);
424 
425 		if (mode->status == MODE_OK)
426 			mode->status = drm_mode_validate_size(mode, maxX, maxY);
427 
428 		if (mode->status == MODE_OK)
429 			mode->status = drm_mode_validate_flag(mode, mode_flags);
430 
431 		if (mode->status == MODE_OK && connector_funcs->mode_valid)
432 			mode->status = connector_funcs->mode_valid(connector,
433 								   mode);
434 	}
435 
436 prune:
437 	drm_mode_prune_invalid(dev, &connector->modes, verbose_prune);
438 
439 	drm_modeset_drop_locks(&ctx);
440 	drm_modeset_acquire_fini(&ctx);
441 
442 	if (list_empty(&connector->modes))
443 		return 0;
444 
445 	list_for_each_entry(mode, &connector->modes, head)
446 		mode->vrefresh = drm_mode_vrefresh(mode);
447 
448 	drm_mode_sort(&connector->modes);
449 
450 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] probed modes :\n", connector->base.id,
451 			connector->name);
452 	list_for_each_entry(mode, &connector->modes, head) {
453 		drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
454 		drm_mode_debug_printmodeline(mode);
455 	}
456 
457 	return count;
458 }
459 EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);
460 
461 /**
462  * drm_kms_helper_hotplug_event - fire off KMS hotplug events
463  * @dev: drm_device whose connector state changed
464  *
465  * This function fires off the uevent for userspace and also calls the
466  * output_poll_changed function, which is most commonly used to inform the fbdev
467  * emulation code and allow it to update the fbcon output configuration.
468  *
469  * Drivers should call this from their hotplug handling code when a change is
470  * detected. Note that this function does not do any output detection of its
471  * own, like drm_helper_hpd_irq_event() does - this is assumed to be done by the
472  * driver already.
473  *
474  * This function must be called from process context with no mode
475  * setting locks held.
476  */
477 void drm_kms_helper_hotplug_event(struct drm_device *dev)
478 {
479 	/* send a uevent + call fbdev */
480 	drm_sysfs_hotplug_event(dev);
481 	if (dev->mode_config.funcs->output_poll_changed)
482 		dev->mode_config.funcs->output_poll_changed(dev);
483 }
484 EXPORT_SYMBOL(drm_kms_helper_hotplug_event);
485 
486 static void output_poll_execute(struct work_struct *work)
487 {
488 	struct delayed_work *delayed_work = to_delayed_work(work);
489 	struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_work);
490 	struct drm_connector *connector;
491 	struct drm_connector_list_iter conn_iter;
492 	enum drm_connector_status old_status;
493 	bool repoll = false, changed;
494 
495 	/* Pick up any changes detected by the probe functions. */
496 	changed = dev->mode_config.delayed_event;
497 	dev->mode_config.delayed_event = false;
498 
499 	if (!drm_kms_helper_poll)
500 		goto out;
501 
502 	if (!mutex_trylock(&dev->mode_config.mutex)) {
503 		repoll = true;
504 		goto out;
505 	}
506 
507 	drm_connector_list_iter_begin(dev, &conn_iter);
508 	drm_for_each_connector_iter(connector, &conn_iter) {
509 		/* Ignore forced connectors. */
510 		if (connector->force)
511 			continue;
512 
513 		/* Ignore HPD capable connectors and connectors where we don't
514 		 * want any hotplug detection at all for polling. */
515 		if (!connector->polled || connector->polled == DRM_CONNECTOR_POLL_HPD)
516 			continue;
517 
518 		old_status = connector->status;
519 		/* if we are connected and don't want to poll for disconnect
520 		   skip it */
521 		if (old_status == connector_status_connected &&
522 		    !(connector->polled & DRM_CONNECTOR_POLL_DISCONNECT))
523 			continue;
524 
525 		repoll = true;
526 
527 		connector->status = drm_helper_probe_detect(connector, NULL, false);
528 		if (old_status != connector->status) {
529 			const char *old, *new;
530 
531 			/*
532 			 * The poll work sets force=false when calling detect so
533 			 * that drivers can avoid to do disruptive tests (e.g.
534 			 * when load detect cycles could cause flickering on
535 			 * other, running displays). This bears the risk that we
536 			 * flip-flop between unknown here in the poll work and
537 			 * the real state when userspace forces a full detect
538 			 * call after receiving a hotplug event due to this
539 			 * change.
540 			 *
541 			 * Hence clamp an unknown detect status to the old
542 			 * value.
543 			 */
544 			if (connector->status == connector_status_unknown) {
545 				connector->status = old_status;
546 				continue;
547 			}
548 
549 			old = drm_get_connector_status_name(old_status);
550 			new = drm_get_connector_status_name(connector->status);
551 
552 			DRM_DEBUG_KMS("[CONNECTOR:%d:%s] "
553 				      "status updated from %s to %s\n",
554 				      connector->base.id,
555 				      connector->name,
556 				      old, new);
557 
558 			changed = true;
559 		}
560 	}
561 	drm_connector_list_iter_end(&conn_iter);
562 
563 	mutex_unlock(&dev->mode_config.mutex);
564 
565 out:
566 	if (changed)
567 		drm_kms_helper_hotplug_event(dev);
568 
569 	if (repoll)
570 		schedule_delayed_work(delayed_work, DRM_OUTPUT_POLL_PERIOD);
571 }
572 
573 /**
574  * drm_kms_helper_poll_disable - disable output polling
575  * @dev: drm_device
576  *
577  * This function disables the output polling work.
578  *
579  * Drivers can call this helper from their device suspend implementation. It is
580  * not an error to call this even when output polling isn't enabled or already
581  * disabled. Polling is re-enabled by calling drm_kms_helper_poll_enable().
582  *
583  * Note that calls to enable and disable polling must be strictly ordered, which
584  * is automatically the case when they're only call from suspend/resume
585  * callbacks.
586  */
587 void drm_kms_helper_poll_disable(struct drm_device *dev)
588 {
589 	if (!dev->mode_config.poll_enabled)
590 		return;
591 	cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
592 }
593 EXPORT_SYMBOL(drm_kms_helper_poll_disable);
594 
595 /**
596  * drm_kms_helper_poll_init - initialize and enable output polling
597  * @dev: drm_device
598  *
599  * This function intializes and then also enables output polling support for
600  * @dev. Drivers which do not have reliable hotplug support in hardware can use
601  * this helper infrastructure to regularly poll such connectors for changes in
602  * their connection state.
603  *
604  * Drivers can control which connectors are polled by setting the
605  * DRM_CONNECTOR_POLL_CONNECT and DRM_CONNECTOR_POLL_DISCONNECT flags. On
606  * connectors where probing live outputs can result in visual distortion drivers
607  * should not set the DRM_CONNECTOR_POLL_DISCONNECT flag to avoid this.
608  * Connectors which have no flag or only DRM_CONNECTOR_POLL_HPD set are
609  * completely ignored by the polling logic.
610  *
611  * Note that a connector can be both polled and probed from the hotplug handler,
612  * in case the hotplug interrupt is known to be unreliable.
613  */
614 void drm_kms_helper_poll_init(struct drm_device *dev)
615 {
616 	INIT_DELAYED_WORK(&dev->mode_config.output_poll_work, output_poll_execute);
617 	dev->mode_config.poll_enabled = true;
618 
619 	drm_kms_helper_poll_enable(dev);
620 }
621 EXPORT_SYMBOL(drm_kms_helper_poll_init);
622 
623 /**
624  * drm_kms_helper_poll_fini - disable output polling and clean it up
625  * @dev: drm_device
626  */
627 void drm_kms_helper_poll_fini(struct drm_device *dev)
628 {
629 	drm_kms_helper_poll_disable(dev);
630 }
631 EXPORT_SYMBOL(drm_kms_helper_poll_fini);
632 
633 /**
634  * drm_helper_hpd_irq_event - hotplug processing
635  * @dev: drm_device
636  *
637  * Drivers can use this helper function to run a detect cycle on all connectors
638  * which have the DRM_CONNECTOR_POLL_HPD flag set in their &polled member. All
639  * other connectors are ignored, which is useful to avoid reprobing fixed
640  * panels.
641  *
642  * This helper function is useful for drivers which can't or don't track hotplug
643  * interrupts for each connector.
644  *
645  * Drivers which support hotplug interrupts for each connector individually and
646  * which have a more fine-grained detect logic should bypass this code and
647  * directly call drm_kms_helper_hotplug_event() in case the connector state
648  * changed.
649  *
650  * This function must be called from process context with no mode
651  * setting locks held.
652  *
653  * Note that a connector can be both polled and probed from the hotplug handler,
654  * in case the hotplug interrupt is known to be unreliable.
655  */
656 bool drm_helper_hpd_irq_event(struct drm_device *dev)
657 {
658 	struct drm_connector *connector;
659 	struct drm_connector_list_iter conn_iter;
660 	enum drm_connector_status old_status;
661 	bool changed = false;
662 
663 	if (!dev->mode_config.poll_enabled)
664 		return false;
665 
666 	mutex_lock(&dev->mode_config.mutex);
667 	drm_connector_list_iter_begin(dev, &conn_iter);
668 	drm_for_each_connector_iter(connector, &conn_iter) {
669 		/* Only handle HPD capable connectors. */
670 		if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
671 			continue;
672 
673 		old_status = connector->status;
674 
675 		connector->status = drm_helper_probe_detect(connector, NULL, false);
676 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
677 			      connector->base.id,
678 			      connector->name,
679 			      drm_get_connector_status_name(old_status),
680 			      drm_get_connector_status_name(connector->status));
681 		if (old_status != connector->status)
682 			changed = true;
683 	}
684 	drm_connector_list_iter_end(&conn_iter);
685 	mutex_unlock(&dev->mode_config.mutex);
686 
687 	if (changed)
688 		drm_kms_helper_hotplug_event(dev);
689 
690 	return changed;
691 }
692 EXPORT_SYMBOL(drm_helper_hpd_irq_event);
693