• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /*
2  * Copyright (c) 2014 Samsung Electronics Co., Ltd
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sub license,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice (including the
12  * next paragraph) shall be included in all copies or substantial portions
13  * of the Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21  * DEALINGS IN THE SOFTWARE.
22  */
23 
24 #include <linux/err.h>
25 #include <linux/module.h>
26 #include <linux/mutex.h>
27 
28 #include <drm/drm_atomic_state_helper.h>
29 #include <drm/drm_bridge.h>
30 #include <drm/drm_encoder.h>
31 #include <drm/drm_of.h>
32 #include <drm/drm_print.h>
33 
34 #include "drm_crtc_internal.h"
35 
36 /**
37  * DOC: overview
38  *
39  * &struct drm_bridge represents a device that hangs on to an encoder. These are
40  * handy when a regular &drm_encoder entity isn't enough to represent the entire
41  * encoder chain.
42  *
43  * A bridge is always attached to a single &drm_encoder at a time, but can be
44  * either connected to it directly, or through a chain of bridges::
45  *
46  *     [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
47  *
48  * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
49  * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
50  * Chaining multiple bridges to the output of a bridge, or the same bridge to
51  * the output of different bridges, is not supported.
52  *
53  * Display drivers are responsible for linking encoders with the first bridge
54  * in the chains. This is done by acquiring the appropriate bridge with
55  * devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
56  * encoder with a call to drm_bridge_attach().
57  *
58  * Bridges are responsible for linking themselves with the next bridge in the
59  * chain, if any. This is done the same way as for encoders, with the call to
60  * drm_bridge_attach() occurring in the &drm_bridge_funcs.attach operation.
61  *
62  * Once these links are created, the bridges can participate along with encoder
63  * functions to perform mode validation and fixup (through
64  * drm_bridge_chain_mode_valid() and drm_atomic_bridge_chain_check()), mode
65  * setting (through drm_bridge_chain_mode_set()), enable (through
66  * drm_atomic_bridge_chain_pre_enable() and drm_atomic_bridge_chain_enable())
67  * and disable (through drm_atomic_bridge_chain_disable() and
68  * drm_atomic_bridge_chain_post_disable()). Those functions call the
69  * corresponding operations provided in &drm_bridge_funcs in sequence for all
70  * bridges in the chain.
71  *
72  * For display drivers that use the atomic helpers
73  * drm_atomic_helper_check_modeset(),
74  * drm_atomic_helper_commit_modeset_enables() and
75  * drm_atomic_helper_commit_modeset_disables() (either directly in hand-rolled
76  * commit check and commit tail handlers, or through the higher-level
77  * drm_atomic_helper_check() and drm_atomic_helper_commit_tail() or
78  * drm_atomic_helper_commit_tail_rpm() helpers), this is done transparently and
79  * requires no intervention from the driver. For other drivers, the relevant
80  * DRM bridge chain functions shall be called manually.
81  *
82  * Bridges also participate in implementing the &drm_connector at the end of
83  * the bridge chain. Display drivers may use the drm_bridge_connector_init()
84  * helper to create the &drm_connector, or implement it manually on top of the
85  * connector-related operations exposed by the bridge (see the overview
86  * documentation of bridge operations for more details).
87  *
88  * &drm_bridge, like &drm_panel, aren't &drm_mode_object entities like planes,
89  * CRTCs, encoders or connectors and hence are not visible to userspace. They
90  * just provide additional hooks to get the desired output at the end of the
91  * encoder chain.
92  */
93 
94 static DEFINE_MUTEX(bridge_lock);
95 static LIST_HEAD(bridge_list);
96 
97 /**
98  * drm_bridge_add - add the given bridge to the global bridge list
99  *
100  * @bridge: bridge control structure
101  */
drm_bridge_add(struct drm_bridge * bridge)102 void drm_bridge_add(struct drm_bridge *bridge)
103 {
104 	mutex_init(&bridge->hpd_mutex);
105 
106 	mutex_lock(&bridge_lock);
107 	list_add_tail(&bridge->list, &bridge_list);
108 	mutex_unlock(&bridge_lock);
109 }
110 EXPORT_SYMBOL(drm_bridge_add);
111 
112 /**
113  * drm_bridge_remove - remove the given bridge from the global bridge list
114  *
115  * @bridge: bridge control structure
116  */
drm_bridge_remove(struct drm_bridge * bridge)117 void drm_bridge_remove(struct drm_bridge *bridge)
118 {
119 	mutex_lock(&bridge_lock);
120 	list_del_init(&bridge->list);
121 	mutex_unlock(&bridge_lock);
122 
123 	mutex_destroy(&bridge->hpd_mutex);
124 }
125 EXPORT_SYMBOL(drm_bridge_remove);
126 
127 static struct drm_private_state *
drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj * obj)128 drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
129 {
130 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);
131 	struct drm_bridge_state *state;
132 
133 	state = bridge->funcs->atomic_duplicate_state(bridge);
134 	return state ? &state->base : NULL;
135 }
136 
137 static void
drm_bridge_atomic_destroy_priv_state(struct drm_private_obj * obj,struct drm_private_state * s)138 drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
139 				     struct drm_private_state *s)
140 {
141 	struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
142 	struct drm_bridge *bridge = drm_priv_to_bridge(obj);
143 
144 	bridge->funcs->atomic_destroy_state(bridge, state);
145 }
146 
147 static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
148 	.atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
149 	.atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
150 };
151 
152 /**
153  * drm_bridge_attach - attach the bridge to an encoder's chain
154  *
155  * @encoder: DRM encoder
156  * @bridge: bridge to attach
157  * @previous: previous bridge in the chain (optional)
158  * @flags: DRM_BRIDGE_ATTACH_* flags
159  *
160  * Called by a kms driver to link the bridge to an encoder's chain. The previous
161  * argument specifies the previous bridge in the chain. If NULL, the bridge is
162  * linked directly at the encoder's output. Otherwise it is linked at the
163  * previous bridge's output.
164  *
165  * If non-NULL the previous bridge must be already attached by a call to this
166  * function.
167  *
168  * Note that bridges attached to encoders are auto-detached during encoder
169  * cleanup in drm_encoder_cleanup(), so drm_bridge_attach() should generally
170  * *not* be balanced with a drm_bridge_detach() in driver code.
171  *
172  * RETURNS:
173  * Zero on success, error code on failure
174  */
drm_bridge_attach(struct drm_encoder * encoder,struct drm_bridge * bridge,struct drm_bridge * previous,enum drm_bridge_attach_flags flags)175 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
176 		      struct drm_bridge *previous,
177 		      enum drm_bridge_attach_flags flags)
178 {
179 	int ret;
180 
181 	if (!encoder || !bridge)
182 		return -EINVAL;
183 
184 	if (previous && (!previous->dev || previous->encoder != encoder))
185 		return -EINVAL;
186 
187 	if (bridge->dev)
188 		return -EBUSY;
189 
190 	bridge->dev = encoder->dev;
191 	bridge->encoder = encoder;
192 
193 	if (previous)
194 		list_add(&bridge->chain_node, &previous->chain_node);
195 	else
196 		list_add(&bridge->chain_node, &encoder->bridge_chain);
197 
198 	if (bridge->funcs->attach) {
199 		ret = bridge->funcs->attach(bridge, flags);
200 		if (ret < 0)
201 			goto err_reset_bridge;
202 	}
203 
204 	if (bridge->funcs->atomic_reset) {
205 		struct drm_bridge_state *state;
206 
207 		state = bridge->funcs->atomic_reset(bridge);
208 		if (IS_ERR(state)) {
209 			ret = PTR_ERR(state);
210 			goto err_detach_bridge;
211 		}
212 
213 		drm_atomic_private_obj_init(bridge->dev, &bridge->base,
214 					    &state->base,
215 					    &drm_bridge_priv_state_funcs);
216 	}
217 
218 	return 0;
219 
220 err_detach_bridge:
221 	if (bridge->funcs->detach)
222 		bridge->funcs->detach(bridge);
223 
224 err_reset_bridge:
225 	bridge->dev = NULL;
226 	bridge->encoder = NULL;
227 	list_del(&bridge->chain_node);
228 
229 #ifdef CONFIG_OF
230 	DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",
231 		  bridge->of_node, encoder->name, ret);
232 #else
233 	DRM_ERROR("failed to attach bridge to encoder %s: %d\n",
234 		  encoder->name, ret);
235 #endif
236 
237 	return ret;
238 }
239 EXPORT_SYMBOL(drm_bridge_attach);
240 
drm_bridge_detach(struct drm_bridge * bridge)241 void drm_bridge_detach(struct drm_bridge *bridge)
242 {
243 	if (WARN_ON(!bridge))
244 		return;
245 
246 	if (WARN_ON(!bridge->dev))
247 		return;
248 
249 	if (bridge->funcs->atomic_reset)
250 		drm_atomic_private_obj_fini(&bridge->base);
251 
252 	if (bridge->funcs->detach)
253 		bridge->funcs->detach(bridge);
254 
255 	list_del(&bridge->chain_node);
256 	bridge->dev = NULL;
257 }
258 
259 /**
260  * DOC: bridge operations
261  *
262  * Bridge drivers expose operations through the &drm_bridge_funcs structure.
263  * The DRM internals (atomic and CRTC helpers) use the helpers defined in
264  * drm_bridge.c to call bridge operations. Those operations are divided in
265  * three big categories to support different parts of the bridge usage.
266  *
267  * - The encoder-related operations support control of the bridges in the
268  *   chain, and are roughly counterparts to the &drm_encoder_helper_funcs
269  *   operations. They are used by the legacy CRTC and the atomic modeset
270  *   helpers to perform mode validation, fixup and setting, and enable and
271  *   disable the bridge automatically.
272  *
273  *   The enable and disable operations are split in
274  *   &drm_bridge_funcs.pre_enable, &drm_bridge_funcs.enable,
275  *   &drm_bridge_funcs.disable and &drm_bridge_funcs.post_disable to provide
276  *   finer-grained control.
277  *
278  *   Bridge drivers may implement the legacy version of those operations, or
279  *   the atomic version (prefixed with atomic\_), in which case they shall also
280  *   implement the atomic state bookkeeping operations
281  *   (&drm_bridge_funcs.atomic_duplicate_state,
282  *   &drm_bridge_funcs.atomic_destroy_state and &drm_bridge_funcs.reset).
283  *   Mixing atomic and non-atomic versions of the operations is not supported.
284  *
285  * - The bus format negotiation operations
286  *   &drm_bridge_funcs.atomic_get_output_bus_fmts and
287  *   &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
288  *   negotiate the formats transmitted between bridges in the chain when
289  *   multiple formats are supported. Negotiation for formats is performed
290  *   transparently for display drivers by the atomic modeset helpers. Only
291  *   atomic versions of those operations exist, bridge drivers that need to
292  *   implement them shall thus also implement the atomic version of the
293  *   encoder-related operations. This feature is not supported by the legacy
294  *   CRTC helpers.
295  *
296  * - The connector-related operations support implementing a &drm_connector
297  *   based on a chain of bridges. DRM bridges traditionally create a
298  *   &drm_connector for bridges meant to be used at the end of the chain. This
299  *   puts additional burden on bridge drivers, especially for bridges that may
300  *   be used in the middle of a chain or at the end of it. Furthermore, it
301  *   requires all operations of the &drm_connector to be handled by a single
302  *   bridge, which doesn't always match the hardware architecture.
303  *
304  *   To simplify bridge drivers and make the connector implementation more
305  *   flexible, a new model allows bridges to unconditionally skip creation of
306  *   &drm_connector and instead expose &drm_bridge_funcs operations to support
307  *   an externally-implemented &drm_connector. Those operations are
308  *   &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes,
309  *   &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify,
310  *   &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When
311  *   implemented, display drivers shall create a &drm_connector instance for
312  *   each chain of bridges, and implement those connector instances based on
313  *   the bridge connector operations.
314  *
315  *   Bridge drivers shall implement the connector-related operations for all
316  *   the features that the bridge hardware support. For instance, if a bridge
317  *   supports reading EDID, the &drm_bridge_funcs.get_edid shall be
318  *   implemented. This however doesn't mean that the DDC lines are wired to the
319  *   bridge on a particular platform, as they could also be connected to an I2C
320  *   controller of the SoC. Support for the connector-related operations on the
321  *   running platform is reported through the &drm_bridge.ops flags. Bridge
322  *   drivers shall detect which operations they can support on the platform
323  *   (usually this information is provided by ACPI or DT), and set the
324  *   &drm_bridge.ops flags for all supported operations. A flag shall only be
325  *   set if the corresponding &drm_bridge_funcs operation is implemented, but
326  *   an implemented operation doesn't necessarily imply that the corresponding
327  *   flag will be set. Display drivers shall use the &drm_bridge.ops flags to
328  *   decide which bridge to delegate a connector operation to. This mechanism
329  *   allows providing a single static const &drm_bridge_funcs instance in
330  *   bridge drivers, improving security by storing function pointers in
331  *   read-only memory.
332  *
333  *   In order to ease transition, bridge drivers may support both the old and
334  *   new models by making connector creation optional and implementing the
335  *   connected-related bridge operations. Connector creation is then controlled
336  *   by the flags argument to the drm_bridge_attach() function. Display drivers
337  *   that support the new model and create connectors themselves shall set the
338  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
339  *   connector creation. For intermediate bridges in the chain, the flag shall
340  *   be passed to the drm_bridge_attach() call for the downstream bridge.
341  *   Bridge drivers that implement the new model only shall return an error
342  *   from their &drm_bridge_funcs.attach handler when the
343  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
344  *   should use the new model, and convert the bridge drivers they use if
345  *   needed, in order to gradually transition to the new model.
346  */
347 
348 /**
349  * drm_bridge_chain_mode_fixup - fixup proposed mode for all bridges in the
350  *				 encoder chain
351  * @bridge: bridge control structure
352  * @mode: desired mode to be set for the bridge
353  * @adjusted_mode: updated mode that works for this bridge
354  *
355  * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the
356  * encoder chain, starting from the first bridge to the last.
357  *
358  * Note: the bridge passed should be the one closest to the encoder
359  *
360  * RETURNS:
361  * true on success, false on failure
362  */
drm_bridge_chain_mode_fixup(struct drm_bridge * bridge,const struct drm_display_mode * mode,struct drm_display_mode * adjusted_mode)363 bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
364 				 const struct drm_display_mode *mode,
365 				 struct drm_display_mode *adjusted_mode)
366 {
367 	struct drm_encoder *encoder;
368 
369 	if (!bridge)
370 		return true;
371 
372 	encoder = bridge->encoder;
373 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
374 		if (!bridge->funcs->mode_fixup)
375 			continue;
376 
377 		if (!bridge->funcs->mode_fixup(bridge, mode, adjusted_mode))
378 			return false;
379 	}
380 
381 	return true;
382 }
383 EXPORT_SYMBOL(drm_bridge_chain_mode_fixup);
384 
385 /**
386  * drm_bridge_chain_mode_valid - validate the mode against all bridges in the
387  *				 encoder chain.
388  * @bridge: bridge control structure
389  * @info: display info against which the mode shall be validated
390  * @mode: desired mode to be validated
391  *
392  * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
393  * chain, starting from the first bridge to the last. If at least one bridge
394  * does not accept the mode the function returns the error code.
395  *
396  * Note: the bridge passed should be the one closest to the encoder.
397  *
398  * RETURNS:
399  * MODE_OK on success, drm_mode_status Enum error code on failure
400  */
401 enum drm_mode_status
drm_bridge_chain_mode_valid(struct drm_bridge * bridge,const struct drm_display_info * info,const struct drm_display_mode * mode)402 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
403 			    const struct drm_display_info *info,
404 			    const struct drm_display_mode *mode)
405 {
406 	struct drm_encoder *encoder;
407 
408 	if (!bridge)
409 		return MODE_OK;
410 
411 	encoder = bridge->encoder;
412 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
413 		enum drm_mode_status ret;
414 
415 		if (!bridge->funcs->mode_valid)
416 			continue;
417 
418 		ret = bridge->funcs->mode_valid(bridge, info, mode);
419 		if (ret != MODE_OK)
420 			return ret;
421 	}
422 
423 	return MODE_OK;
424 }
425 EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
426 
427 /**
428  * drm_bridge_chain_disable - disables all bridges in the encoder chain
429  * @bridge: bridge control structure
430  *
431  * Calls &drm_bridge_funcs.disable op for all the bridges in the encoder
432  * chain, starting from the last bridge to the first. These are called before
433  * calling the encoder's prepare op.
434  *
435  * Note: the bridge passed should be the one closest to the encoder
436  */
drm_bridge_chain_disable(struct drm_bridge * bridge)437 void drm_bridge_chain_disable(struct drm_bridge *bridge)
438 {
439 	struct drm_encoder *encoder;
440 	struct drm_bridge *iter;
441 
442 	if (!bridge)
443 		return;
444 
445 	encoder = bridge->encoder;
446 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
447 		if (iter->funcs->disable)
448 			iter->funcs->disable(iter);
449 
450 		if (iter == bridge)
451 			break;
452 	}
453 }
454 EXPORT_SYMBOL(drm_bridge_chain_disable);
455 
456 /**
457  * drm_bridge_chain_post_disable - cleans up after disabling all bridges in the
458  *				   encoder chain
459  * @bridge: bridge control structure
460  *
461  * Calls &drm_bridge_funcs.post_disable op for all the bridges in the
462  * encoder chain, starting from the first bridge to the last. These are called
463  * after completing the encoder's prepare op.
464  *
465  * Note: the bridge passed should be the one closest to the encoder
466  */
drm_bridge_chain_post_disable(struct drm_bridge * bridge)467 void drm_bridge_chain_post_disable(struct drm_bridge *bridge)
468 {
469 	struct drm_encoder *encoder;
470 
471 	if (!bridge)
472 		return;
473 
474 	encoder = bridge->encoder;
475 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
476 		if (bridge->funcs->post_disable)
477 			bridge->funcs->post_disable(bridge);
478 	}
479 }
480 EXPORT_SYMBOL(drm_bridge_chain_post_disable);
481 
482 /**
483  * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
484  *			       encoder chain
485  * @bridge: bridge control structure
486  * @mode: desired mode to be set for the encoder chain
487  * @adjusted_mode: updated mode that works for this encoder chain
488  *
489  * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
490  * encoder chain, starting from the first bridge to the last.
491  *
492  * Note: the bridge passed should be the one closest to the encoder
493  */
drm_bridge_chain_mode_set(struct drm_bridge * bridge,const struct drm_display_mode * mode,const struct drm_display_mode * adjusted_mode)494 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
495 			       const struct drm_display_mode *mode,
496 			       const struct drm_display_mode *adjusted_mode)
497 {
498 	struct drm_encoder *encoder;
499 
500 	if (!bridge)
501 		return;
502 
503 	encoder = bridge->encoder;
504 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
505 		if (bridge->funcs->mode_set)
506 			bridge->funcs->mode_set(bridge, mode, adjusted_mode);
507 	}
508 }
509 EXPORT_SYMBOL(drm_bridge_chain_mode_set);
510 
511 /**
512  * drm_bridge_chain_pre_enable - prepares for enabling all bridges in the
513  *				 encoder chain
514  * @bridge: bridge control structure
515  *
516  * Calls &drm_bridge_funcs.pre_enable op for all the bridges in the encoder
517  * chain, starting from the last bridge to the first. These are called
518  * before calling the encoder's commit op.
519  *
520  * Note: the bridge passed should be the one closest to the encoder
521  */
drm_bridge_chain_pre_enable(struct drm_bridge * bridge)522 void drm_bridge_chain_pre_enable(struct drm_bridge *bridge)
523 {
524 	struct drm_encoder *encoder;
525 	struct drm_bridge *iter;
526 
527 	if (!bridge)
528 		return;
529 
530 	encoder = bridge->encoder;
531 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
532 		if (iter->funcs->pre_enable)
533 			iter->funcs->pre_enable(iter);
534 
535 		if (iter == bridge)
536 			break;
537 	}
538 }
539 EXPORT_SYMBOL(drm_bridge_chain_pre_enable);
540 
541 /**
542  * drm_bridge_chain_enable - enables all bridges in the encoder chain
543  * @bridge: bridge control structure
544  *
545  * Calls &drm_bridge_funcs.enable op for all the bridges in the encoder
546  * chain, starting from the first bridge to the last. These are called
547  * after completing the encoder's commit op.
548  *
549  * Note that the bridge passed should be the one closest to the encoder
550  */
drm_bridge_chain_enable(struct drm_bridge * bridge)551 void drm_bridge_chain_enable(struct drm_bridge *bridge)
552 {
553 	struct drm_encoder *encoder;
554 
555 	if (!bridge)
556 		return;
557 
558 	encoder = bridge->encoder;
559 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
560 		if (bridge->funcs->enable)
561 			bridge->funcs->enable(bridge);
562 	}
563 }
564 EXPORT_SYMBOL(drm_bridge_chain_enable);
565 
566 /**
567  * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
568  * @bridge: bridge control structure
569  * @old_state: old atomic state
570  *
571  * Calls &drm_bridge_funcs.atomic_disable (falls back on
572  * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
573  * starting from the last bridge to the first. These are called before calling
574  * &drm_encoder_helper_funcs.atomic_disable
575  *
576  * Note: the bridge passed should be the one closest to the encoder
577  */
drm_atomic_bridge_chain_disable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)578 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
579 				     struct drm_atomic_state *old_state)
580 {
581 	struct drm_encoder *encoder;
582 	struct drm_bridge *iter;
583 
584 	if (!bridge)
585 		return;
586 
587 	encoder = bridge->encoder;
588 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
589 		if (iter->funcs->atomic_disable) {
590 			struct drm_bridge_state *old_bridge_state;
591 
592 			old_bridge_state =
593 				drm_atomic_get_old_bridge_state(old_state,
594 								iter);
595 			if (WARN_ON(!old_bridge_state))
596 				return;
597 
598 			iter->funcs->atomic_disable(iter, old_bridge_state);
599 		} else if (iter->funcs->disable) {
600 			iter->funcs->disable(iter);
601 		}
602 
603 		if (iter == bridge)
604 			break;
605 	}
606 }
607 EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
608 
609 /**
610  * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
611  *					  in the encoder chain
612  * @bridge: bridge control structure
613  * @old_state: old atomic state
614  *
615  * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
616  * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
617  * starting from the first bridge to the last. These are called after completing
618  * &drm_encoder_helper_funcs.atomic_disable
619  *
620  * Note: the bridge passed should be the one closest to the encoder
621  */
drm_atomic_bridge_chain_post_disable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)622 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
623 					  struct drm_atomic_state *old_state)
624 {
625 	struct drm_encoder *encoder;
626 
627 	if (!bridge)
628 		return;
629 
630 	encoder = bridge->encoder;
631 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
632 		if (bridge->funcs->atomic_post_disable) {
633 			struct drm_bridge_state *old_bridge_state;
634 
635 			old_bridge_state =
636 				drm_atomic_get_old_bridge_state(old_state,
637 								bridge);
638 			if (WARN_ON(!old_bridge_state))
639 				return;
640 
641 			bridge->funcs->atomic_post_disable(bridge,
642 							   old_bridge_state);
643 		} else if (bridge->funcs->post_disable) {
644 			bridge->funcs->post_disable(bridge);
645 		}
646 	}
647 }
648 EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
649 
650 /**
651  * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
652  *					the encoder chain
653  * @bridge: bridge control structure
654  * @old_state: old atomic state
655  *
656  * Calls &drm_bridge_funcs.atomic_pre_enable (falls back on
657  * &drm_bridge_funcs.pre_enable) op for all the bridges in the encoder chain,
658  * starting from the last bridge to the first. These are called before calling
659  * &drm_encoder_helper_funcs.atomic_enable
660  *
661  * Note: the bridge passed should be the one closest to the encoder
662  */
drm_atomic_bridge_chain_pre_enable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)663 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
664 					struct drm_atomic_state *old_state)
665 {
666 	struct drm_encoder *encoder;
667 	struct drm_bridge *iter;
668 
669 	if (!bridge)
670 		return;
671 
672 	encoder = bridge->encoder;
673 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
674 		if (iter->funcs->atomic_pre_enable) {
675 			struct drm_bridge_state *old_bridge_state;
676 
677 			old_bridge_state =
678 				drm_atomic_get_old_bridge_state(old_state,
679 								iter);
680 			if (WARN_ON(!old_bridge_state))
681 				return;
682 
683 			iter->funcs->atomic_pre_enable(iter, old_bridge_state);
684 		} else if (iter->funcs->pre_enable) {
685 			iter->funcs->pre_enable(iter);
686 		}
687 
688 		if (iter == bridge)
689 			break;
690 	}
691 }
692 EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable);
693 
694 /**
695  * drm_atomic_bridge_chain_enable - enables all bridges in the encoder chain
696  * @bridge: bridge control structure
697  * @old_state: old atomic state
698  *
699  * Calls &drm_bridge_funcs.atomic_enable (falls back on
700  * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
701  * starting from the first bridge to the last. These are called after completing
702  * &drm_encoder_helper_funcs.atomic_enable
703  *
704  * Note: the bridge passed should be the one closest to the encoder
705  */
drm_atomic_bridge_chain_enable(struct drm_bridge * bridge,struct drm_atomic_state * old_state)706 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
707 				    struct drm_atomic_state *old_state)
708 {
709 	struct drm_encoder *encoder;
710 
711 	if (!bridge)
712 		return;
713 
714 	encoder = bridge->encoder;
715 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
716 		if (bridge->funcs->atomic_enable) {
717 			struct drm_bridge_state *old_bridge_state;
718 
719 			old_bridge_state =
720 				drm_atomic_get_old_bridge_state(old_state,
721 								bridge);
722 			if (WARN_ON(!old_bridge_state))
723 				return;
724 
725 			bridge->funcs->atomic_enable(bridge, old_bridge_state);
726 		} else if (bridge->funcs->enable) {
727 			bridge->funcs->enable(bridge);
728 		}
729 	}
730 }
731 EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
732 
drm_atomic_bridge_check(struct drm_bridge * bridge,struct drm_crtc_state * crtc_state,struct drm_connector_state * conn_state)733 static int drm_atomic_bridge_check(struct drm_bridge *bridge,
734 				   struct drm_crtc_state *crtc_state,
735 				   struct drm_connector_state *conn_state)
736 {
737 	if (bridge->funcs->atomic_check) {
738 		struct drm_bridge_state *bridge_state;
739 		int ret;
740 
741 		bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
742 							       bridge);
743 		if (WARN_ON(!bridge_state))
744 			return -EINVAL;
745 
746 		ret = bridge->funcs->atomic_check(bridge, bridge_state,
747 						  crtc_state, conn_state);
748 		if (ret)
749 			return ret;
750 	} else if (bridge->funcs->mode_fixup) {
751 		if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
752 					       &crtc_state->adjusted_mode))
753 			return -EINVAL;
754 	}
755 
756 	return 0;
757 }
758 
select_bus_fmt_recursive(struct drm_bridge * first_bridge,struct drm_bridge * cur_bridge,struct drm_crtc_state * crtc_state,struct drm_connector_state * conn_state,u32 out_bus_fmt)759 static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
760 				    struct drm_bridge *cur_bridge,
761 				    struct drm_crtc_state *crtc_state,
762 				    struct drm_connector_state *conn_state,
763 				    u32 out_bus_fmt)
764 {
765 	unsigned int i, num_in_bus_fmts = 0;
766 	struct drm_bridge_state *cur_state;
767 	struct drm_bridge *prev_bridge;
768 	u32 *in_bus_fmts;
769 	int ret;
770 
771 	prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
772 	cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
773 						    cur_bridge);
774 
775 	/*
776 	 * If bus format negotiation is not supported by this bridge, let's
777 	 * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and
778 	 * hope that it can handle this situation gracefully (by providing
779 	 * appropriate default values).
780 	 */
781 	if (!cur_bridge->funcs->atomic_get_input_bus_fmts) {
782 		if (cur_bridge != first_bridge) {
783 			ret = select_bus_fmt_recursive(first_bridge,
784 						       prev_bridge, crtc_state,
785 						       conn_state,
786 						       MEDIA_BUS_FMT_FIXED);
787 			if (ret)
788 				return ret;
789 		}
790 
791 		/*
792 		 * Driver does not implement the atomic state hooks, but that's
793 		 * fine, as long as it does not access the bridge state.
794 		 */
795 		if (cur_state) {
796 			cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED;
797 			cur_state->output_bus_cfg.format = out_bus_fmt;
798 		}
799 
800 		return 0;
801 	}
802 
803 	/*
804 	 * If the driver implements ->atomic_get_input_bus_fmts() it
805 	 * should also implement the atomic state hooks.
806 	 */
807 	if (WARN_ON(!cur_state))
808 		return -EINVAL;
809 
810 	in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge,
811 							cur_state,
812 							crtc_state,
813 							conn_state,
814 							out_bus_fmt,
815 							&num_in_bus_fmts);
816 	if (!num_in_bus_fmts)
817 		return -ENOTSUPP;
818 	else if (!in_bus_fmts)
819 		return -ENOMEM;
820 
821 	if (first_bridge == cur_bridge) {
822 		cur_state->input_bus_cfg.format = in_bus_fmts[0];
823 		cur_state->output_bus_cfg.format = out_bus_fmt;
824 		kfree(in_bus_fmts);
825 		return 0;
826 	}
827 
828 	for (i = 0; i < num_in_bus_fmts; i++) {
829 		ret = select_bus_fmt_recursive(first_bridge, prev_bridge,
830 					       crtc_state, conn_state,
831 					       in_bus_fmts[i]);
832 		if (ret != -ENOTSUPP)
833 			break;
834 	}
835 
836 	if (!ret) {
837 		cur_state->input_bus_cfg.format = in_bus_fmts[i];
838 		cur_state->output_bus_cfg.format = out_bus_fmt;
839 	}
840 
841 	kfree(in_bus_fmts);
842 	return ret;
843 }
844 
845 /*
846  * This function is called by &drm_atomic_bridge_chain_check() just before
847  * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
848  * It performs bus format negotiation between bridge elements. The negotiation
849  * happens in reverse order, starting from the last element in the chain up to
850  * @bridge.
851  *
852  * Negotiation starts by retrieving supported output bus formats on the last
853  * bridge element and testing them one by one. The test is recursive, meaning
854  * that for each tested output format, the whole chain will be walked backward,
855  * and each element will have to choose an input bus format that can be
856  * transcoded to the requested output format. When a bridge element does not
857  * support transcoding into a specific output format -ENOTSUPP is returned and
858  * the next bridge element will have to try a different format. If none of the
859  * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail.
860  *
861  * This implementation is relying on
862  * &drm_bridge_funcs.atomic_get_output_bus_fmts() and
863  * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported
864  * input/output formats.
865  *
866  * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by
867  * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts()
868  * tries a single format: &drm_connector.display_info.bus_formats[0] if
869  * available, MEDIA_BUS_FMT_FIXED otherwise.
870  *
871  * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented,
872  * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the
873  * bridge element that lacks this hook and asks the previous element in the
874  * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
875  * to do in that case (fail if they want to enforce bus format negotiation, or
876  * provide a reasonable default if they need to support pipelines where not
877  * all elements support bus format negotiation).
878  */
879 static int
drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge * bridge,struct drm_crtc_state * crtc_state,struct drm_connector_state * conn_state)880 drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,
881 					struct drm_crtc_state *crtc_state,
882 					struct drm_connector_state *conn_state)
883 {
884 	struct drm_connector *conn = conn_state->connector;
885 	struct drm_encoder *encoder = bridge->encoder;
886 	struct drm_bridge_state *last_bridge_state;
887 	unsigned int i, num_out_bus_fmts = 0;
888 	struct drm_bridge *last_bridge;
889 	u32 *out_bus_fmts;
890 	int ret = 0;
891 
892 	last_bridge = list_last_entry(&encoder->bridge_chain,
893 				      struct drm_bridge, chain_node);
894 	last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
895 							    last_bridge);
896 
897 	if (last_bridge->funcs->atomic_get_output_bus_fmts) {
898 		const struct drm_bridge_funcs *funcs = last_bridge->funcs;
899 
900 		/*
901 		 * If the driver implements ->atomic_get_output_bus_fmts() it
902 		 * should also implement the atomic state hooks.
903 		 */
904 		if (WARN_ON(!last_bridge_state))
905 			return -EINVAL;
906 
907 		out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge,
908 							last_bridge_state,
909 							crtc_state,
910 							conn_state,
911 							&num_out_bus_fmts);
912 		if (!num_out_bus_fmts)
913 			return -ENOTSUPP;
914 		else if (!out_bus_fmts)
915 			return -ENOMEM;
916 	} else {
917 		num_out_bus_fmts = 1;
918 		out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
919 		if (!out_bus_fmts)
920 			return -ENOMEM;
921 
922 		if (conn->display_info.num_bus_formats &&
923 		    conn->display_info.bus_formats)
924 			out_bus_fmts[0] = conn->display_info.bus_formats[0];
925 		else
926 			out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
927 	}
928 
929 	for (i = 0; i < num_out_bus_fmts; i++) {
930 		ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
931 					       conn_state, out_bus_fmts[i]);
932 		if (ret != -ENOTSUPP)
933 			break;
934 	}
935 
936 	kfree(out_bus_fmts);
937 
938 	return ret;
939 }
940 
941 static void
drm_atomic_bridge_propagate_bus_flags(struct drm_bridge * bridge,struct drm_connector * conn,struct drm_atomic_state * state)942 drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,
943 				      struct drm_connector *conn,
944 				      struct drm_atomic_state *state)
945 {
946 	struct drm_bridge_state *bridge_state, *next_bridge_state;
947 	struct drm_bridge *next_bridge;
948 	u32 output_flags = 0;
949 
950 	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
951 
952 	/* No bridge state attached to this bridge => nothing to propagate. */
953 	if (!bridge_state)
954 		return;
955 
956 	next_bridge = drm_bridge_get_next_bridge(bridge);
957 
958 	/*
959 	 * Let's try to apply the most common case here, that is, propagate
960 	 * display_info flags for the last bridge, and propagate the input
961 	 * flags of the next bridge element to the output end of the current
962 	 * bridge when the bridge is not the last one.
963 	 * There are exceptions to this rule, like when signal inversion is
964 	 * happening at the board level, but that's something drivers can deal
965 	 * with from their &drm_bridge_funcs.atomic_check() implementation by
966 	 * simply overriding the flags value we've set here.
967 	 */
968 	if (!next_bridge) {
969 		output_flags = conn->display_info.bus_flags;
970 	} else {
971 		next_bridge_state = drm_atomic_get_new_bridge_state(state,
972 								next_bridge);
973 		/*
974 		 * No bridge state attached to the next bridge, just leave the
975 		 * flags to 0.
976 		 */
977 		if (next_bridge_state)
978 			output_flags = next_bridge_state->input_bus_cfg.flags;
979 	}
980 
981 	bridge_state->output_bus_cfg.flags = output_flags;
982 
983 	/*
984 	 * Propagate the output flags to the input end of the bridge. Again, it's
985 	 * not necessarily what all bridges want, but that's what most of them
986 	 * do, and by doing that by default we avoid forcing drivers to
987 	 * duplicate the "dummy propagation" logic.
988 	 */
989 	bridge_state->input_bus_cfg.flags = output_flags;
990 }
991 
992 /**
993  * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
994  * @bridge: bridge control structure
995  * @crtc_state: new CRTC state
996  * @conn_state: new connector state
997  *
998  * First trigger a bus format negotiation before calling
999  * &drm_bridge_funcs.atomic_check() (falls back on
1000  * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
1001  * starting from the last bridge to the first. These are called before calling
1002  * &drm_encoder_helper_funcs.atomic_check()
1003  *
1004  * RETURNS:
1005  * 0 on success, a negative error code on failure
1006  */
drm_atomic_bridge_chain_check(struct drm_bridge * bridge,struct drm_crtc_state * crtc_state,struct drm_connector_state * conn_state)1007 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
1008 				  struct drm_crtc_state *crtc_state,
1009 				  struct drm_connector_state *conn_state)
1010 {
1011 	struct drm_connector *conn = conn_state->connector;
1012 	struct drm_encoder *encoder;
1013 	struct drm_bridge *iter;
1014 	int ret;
1015 
1016 	if (!bridge)
1017 		return 0;
1018 
1019 	ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,
1020 						      conn_state);
1021 	if (ret)
1022 		return ret;
1023 
1024 	encoder = bridge->encoder;
1025 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
1026 		int ret;
1027 
1028 		/*
1029 		 * Bus flags are propagated by default. If a bridge needs to
1030 		 * tweak the input bus flags for any reason, it should happen
1031 		 * in its &drm_bridge_funcs.atomic_check() implementation such
1032 		 * that preceding bridges in the chain can propagate the new
1033 		 * bus flags.
1034 		 */
1035 		drm_atomic_bridge_propagate_bus_flags(iter, conn,
1036 						      crtc_state->state);
1037 
1038 		ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
1039 		if (ret)
1040 			return ret;
1041 
1042 		if (iter == bridge)
1043 			break;
1044 	}
1045 
1046 	return 0;
1047 }
1048 EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
1049 
1050 /**
1051  * drm_bridge_detect - check if anything is attached to the bridge output
1052  * @bridge: bridge control structure
1053  *
1054  * If the bridge supports output detection, as reported by the
1055  * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
1056  * bridge and return the connection status. Otherwise return
1057  * connector_status_unknown.
1058  *
1059  * RETURNS:
1060  * The detection status on success, or connector_status_unknown if the bridge
1061  * doesn't support output detection.
1062  */
drm_bridge_detect(struct drm_bridge * bridge)1063 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)
1064 {
1065 	if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))
1066 		return connector_status_unknown;
1067 
1068 	return bridge->funcs->detect(bridge);
1069 }
1070 EXPORT_SYMBOL_GPL(drm_bridge_detect);
1071 
1072 /**
1073  * drm_bridge_get_modes - fill all modes currently valid for the sink into the
1074  * @connector
1075  * @bridge: bridge control structure
1076  * @connector: the connector to fill with modes
1077  *
1078  * If the bridge supports output modes retrieval, as reported by the
1079  * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
1080  * fill the connector with all valid modes and return the number of modes
1081  * added. Otherwise return 0.
1082  *
1083  * RETURNS:
1084  * The number of modes added to the connector.
1085  */
drm_bridge_get_modes(struct drm_bridge * bridge,struct drm_connector * connector)1086 int drm_bridge_get_modes(struct drm_bridge *bridge,
1087 			 struct drm_connector *connector)
1088 {
1089 	if (!(bridge->ops & DRM_BRIDGE_OP_MODES))
1090 		return 0;
1091 
1092 	return bridge->funcs->get_modes(bridge, connector);
1093 }
1094 EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
1095 
1096 /**
1097  * drm_bridge_get_edid - get the EDID data of the connected display
1098  * @bridge: bridge control structure
1099  * @connector: the connector to read EDID for
1100  *
1101  * If the bridge supports output EDID retrieval, as reported by the
1102  * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
1103  * get the EDID and return it. Otherwise return NULL.
1104  *
1105  * RETURNS:
1106  * The retrieved EDID on success, or NULL otherwise.
1107  */
drm_bridge_get_edid(struct drm_bridge * bridge,struct drm_connector * connector)1108 struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,
1109 				 struct drm_connector *connector)
1110 {
1111 	if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
1112 		return NULL;
1113 
1114 	return bridge->funcs->get_edid(bridge, connector);
1115 }
1116 EXPORT_SYMBOL_GPL(drm_bridge_get_edid);
1117 
1118 /**
1119  * drm_bridge_hpd_enable - enable hot plug detection for the bridge
1120  * @bridge: bridge control structure
1121  * @cb: hot-plug detection callback
1122  * @data: data to be passed to the hot-plug detection callback
1123  *
1124  * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb
1125  * and @data as hot plug notification callback. From now on the @cb will be
1126  * called with @data when an output status change is detected by the bridge,
1127  * until hot plug notification gets disabled with drm_bridge_hpd_disable().
1128  *
1129  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1130  * bridge->ops. This function shall not be called when the flag is not set.
1131  *
1132  * Only one hot plug detection callback can be registered at a time, it is an
1133  * error to call this function when hot plug detection is already enabled for
1134  * the bridge.
1135  */
drm_bridge_hpd_enable(struct drm_bridge * bridge,void (* cb)(void * data,enum drm_connector_status status),void * data)1136 void drm_bridge_hpd_enable(struct drm_bridge *bridge,
1137 			   void (*cb)(void *data,
1138 				      enum drm_connector_status status),
1139 			   void *data)
1140 {
1141 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1142 		return;
1143 
1144 	mutex_lock(&bridge->hpd_mutex);
1145 
1146 	if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))
1147 		goto unlock;
1148 
1149 	bridge->hpd_cb = cb;
1150 	bridge->hpd_data = data;
1151 
1152 	if (bridge->funcs->hpd_enable)
1153 		bridge->funcs->hpd_enable(bridge);
1154 
1155 unlock:
1156 	mutex_unlock(&bridge->hpd_mutex);
1157 }
1158 EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable);
1159 
1160 /**
1161  * drm_bridge_hpd_disable - disable hot plug detection for the bridge
1162  * @bridge: bridge control structure
1163  *
1164  * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot
1165  * plug detection callback previously registered with drm_bridge_hpd_enable().
1166  * Once this function returns the callback will not be called by the bridge
1167  * when an output status change occurs.
1168  *
1169  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
1170  * bridge->ops. This function shall not be called when the flag is not set.
1171  */
drm_bridge_hpd_disable(struct drm_bridge * bridge)1172 void drm_bridge_hpd_disable(struct drm_bridge *bridge)
1173 {
1174 	if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
1175 		return;
1176 
1177 	mutex_lock(&bridge->hpd_mutex);
1178 	if (bridge->funcs->hpd_disable)
1179 		bridge->funcs->hpd_disable(bridge);
1180 
1181 	bridge->hpd_cb = NULL;
1182 	bridge->hpd_data = NULL;
1183 	mutex_unlock(&bridge->hpd_mutex);
1184 }
1185 EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable);
1186 
1187 /**
1188  * drm_bridge_hpd_notify - notify hot plug detection events
1189  * @bridge: bridge control structure
1190  * @status: output connection status
1191  *
1192  * Bridge drivers shall call this function to report hot plug events when they
1193  * detect a change in the output status, when hot plug detection has been
1194  * enabled by drm_bridge_hpd_enable().
1195  *
1196  * This function shall be called in a context that can sleep.
1197  */
drm_bridge_hpd_notify(struct drm_bridge * bridge,enum drm_connector_status status)1198 void drm_bridge_hpd_notify(struct drm_bridge *bridge,
1199 			   enum drm_connector_status status)
1200 {
1201 	mutex_lock(&bridge->hpd_mutex);
1202 	if (bridge->hpd_cb)
1203 		bridge->hpd_cb(bridge->hpd_data, status);
1204 	mutex_unlock(&bridge->hpd_mutex);
1205 }
1206 EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
1207 
1208 #ifdef CONFIG_OF
1209 /**
1210  * of_drm_find_bridge - find the bridge corresponding to the device node in
1211  *			the global bridge list
1212  *
1213  * @np: device node
1214  *
1215  * RETURNS:
1216  * drm_bridge control struct on success, NULL on failure
1217  */
of_drm_find_bridge(struct device_node * np)1218 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
1219 {
1220 	struct drm_bridge *bridge;
1221 
1222 	mutex_lock(&bridge_lock);
1223 
1224 	list_for_each_entry(bridge, &bridge_list, list) {
1225 		if (bridge->of_node == np) {
1226 			mutex_unlock(&bridge_lock);
1227 			return bridge;
1228 		}
1229 	}
1230 
1231 	mutex_unlock(&bridge_lock);
1232 	return NULL;
1233 }
1234 EXPORT_SYMBOL(of_drm_find_bridge);
1235 #endif
1236 
1237 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
1238 MODULE_DESCRIPTION("DRM bridge infrastructure");
1239 MODULE_LICENSE("GPL and additional rights");
1240