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Laurent Pinchart53e269c2009-12-09 08:40:00 -03001/*
2 * Media entity
3 *
4 * Copyright (C) 2010 Nokia Corporation
5 *
6 * Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
7 * Sakari Ailus <sakari.ailus@iki.fi>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 */
22
Laurent Pinchart5c7b25b2013-06-07 12:45:11 -030023#include <linux/bitmap.h>
Laurent Pinchart53e269c2009-12-09 08:40:00 -030024#include <linux/module.h>
25#include <linux/slab.h>
26#include <media/media-entity.h>
Laurent Pinchart503c3d822010-03-07 15:04:59 -030027#include <media/media-device.h>
Laurent Pinchart53e269c2009-12-09 08:40:00 -030028
29/**
30 * media_entity_init - Initialize a media entity
31 *
32 * @num_pads: Total number of sink and source pads.
33 * @extra_links: Initial estimate of the number of extra links.
34 * @pads: Array of 'num_pads' pads.
35 *
36 * The total number of pads is an intrinsic property of entities known by the
37 * entity driver, while the total number of links depends on hardware design
38 * and is an extrinsic property unknown to the entity driver. However, in most
39 * use cases the entity driver can guess the number of links which can safely
40 * be assumed to be equal to or larger than the number of pads.
41 *
42 * For those reasons the links array can be preallocated based on the entity
43 * driver guess and will be reallocated later if extra links need to be
44 * created.
45 *
46 * This function allocates a links array with enough space to hold at least
47 * 'num_pads' + 'extra_links' elements. The media_entity::max_links field will
48 * be set to the number of allocated elements.
49 *
50 * The pads array is managed by the entity driver and passed to
51 * media_entity_init() where its pointer will be stored in the entity structure.
52 */
53int
54media_entity_init(struct media_entity *entity, u16 num_pads,
55 struct media_pad *pads, u16 extra_links)
56{
57 struct media_link *links;
58 unsigned int max_links = num_pads + extra_links;
59 unsigned int i;
60
61 links = kzalloc(max_links * sizeof(links[0]), GFP_KERNEL);
62 if (links == NULL)
63 return -ENOMEM;
64
65 entity->group_id = 0;
66 entity->max_links = max_links;
67 entity->num_links = 0;
68 entity->num_backlinks = 0;
69 entity->num_pads = num_pads;
70 entity->pads = pads;
71 entity->links = links;
72
73 for (i = 0; i < num_pads; i++) {
74 pads[i].entity = entity;
75 pads[i].index = i;
76 }
77
78 return 0;
79}
80EXPORT_SYMBOL_GPL(media_entity_init);
81
82void
83media_entity_cleanup(struct media_entity *entity)
84{
85 kfree(entity->links);
86}
87EXPORT_SYMBOL_GPL(media_entity_cleanup);
88
Sakari Ailusa5ccc482010-03-07 16:14:14 -030089/* -----------------------------------------------------------------------------
90 * Graph traversal
91 */
92
93static struct media_entity *
94media_entity_other(struct media_entity *entity, struct media_link *link)
95{
96 if (link->source->entity == entity)
97 return link->sink->entity;
98 else
99 return link->source->entity;
100}
101
102/* push an entity to traversal stack */
103static void stack_push(struct media_entity_graph *graph,
104 struct media_entity *entity)
105{
106 if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
107 WARN_ON(1);
108 return;
109 }
110 graph->top++;
111 graph->stack[graph->top].link = 0;
112 graph->stack[graph->top].entity = entity;
113}
114
115static struct media_entity *stack_pop(struct media_entity_graph *graph)
116{
117 struct media_entity *entity;
118
119 entity = graph->stack[graph->top].entity;
120 graph->top--;
121
122 return entity;
123}
124
Sakari Ailusa5ccc482010-03-07 16:14:14 -0300125#define link_top(en) ((en)->stack[(en)->top].link)
126#define stack_top(en) ((en)->stack[(en)->top].entity)
127
128/**
129 * media_entity_graph_walk_start - Start walking the media graph at a given entity
130 * @graph: Media graph structure that will be used to walk the graph
131 * @entity: Starting entity
132 *
133 * This function initializes the graph traversal structure to walk the entities
134 * graph starting at the given entity. The traversal structure must not be
135 * modified by the caller during graph traversal. When done the structure can
136 * safely be freed.
137 */
138void media_entity_graph_walk_start(struct media_entity_graph *graph,
139 struct media_entity *entity)
140{
141 graph->top = 0;
142 graph->stack[graph->top].entity = NULL;
Laurent Pinchart5c7b25b2013-06-07 12:45:11 -0300143 bitmap_zero(graph->entities, MEDIA_ENTITY_ENUM_MAX_ID);
144
145 if (WARN_ON(entity->id >= MEDIA_ENTITY_ENUM_MAX_ID))
146 return;
147
148 __set_bit(entity->id, graph->entities);
Sakari Ailusa5ccc482010-03-07 16:14:14 -0300149 stack_push(graph, entity);
150}
151EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
152
153/**
154 * media_entity_graph_walk_next - Get the next entity in the graph
155 * @graph: Media graph structure
156 *
157 * Perform a depth-first traversal of the given media entities graph.
158 *
159 * The graph structure must have been previously initialized with a call to
160 * media_entity_graph_walk_start().
161 *
162 * Return the next entity in the graph or NULL if the whole graph have been
163 * traversed.
164 */
165struct media_entity *
166media_entity_graph_walk_next(struct media_entity_graph *graph)
167{
168 if (stack_top(graph) == NULL)
169 return NULL;
170
171 /*
172 * Depth first search. Push entity to stack and continue from
173 * top of the stack until no more entities on the level can be
174 * found.
175 */
176 while (link_top(graph) < stack_top(graph)->num_links) {
177 struct media_entity *entity = stack_top(graph);
178 struct media_link *link = &entity->links[link_top(graph)];
179 struct media_entity *next;
180
181 /* The link is not enabled so we do not follow. */
182 if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
183 link_top(graph)++;
184 continue;
185 }
186
187 /* Get the entity in the other end of the link . */
188 next = media_entity_other(entity, link);
Laurent Pinchart5c7b25b2013-06-07 12:45:11 -0300189 if (WARN_ON(next->id >= MEDIA_ENTITY_ENUM_MAX_ID))
190 return NULL;
Sakari Ailusa5ccc482010-03-07 16:14:14 -0300191
Laurent Pinchart5c7b25b2013-06-07 12:45:11 -0300192 /* Has the entity already been visited? */
193 if (__test_and_set_bit(next->id, graph->entities)) {
Sakari Ailusa5ccc482010-03-07 16:14:14 -0300194 link_top(graph)++;
195 continue;
196 }
197
198 /* Push the new entity to stack and start over. */
199 link_top(graph)++;
200 stack_push(graph, next);
201 }
202
203 return stack_pop(graph);
204}
205EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
206
207/* -----------------------------------------------------------------------------
Laurent Pincharte02188c2010-08-25 09:00:41 -0300208 * Pipeline management
209 */
210
211/**
212 * media_entity_pipeline_start - Mark a pipeline as streaming
213 * @entity: Starting entity
214 * @pipe: Media pipeline to be assigned to all entities in the pipeline.
215 *
216 * Mark all entities connected to a given entity through enabled links, either
217 * directly or indirectly, as streaming. The given pipeline object is assigned to
218 * every entity in the pipeline and stored in the media_entity pipe field.
219 *
220 * Calls to this function can be nested, in which case the same number of
221 * media_entity_pipeline_stop() calls will be required to stop streaming. The
222 * pipeline pointer must be identical for all nested calls to
223 * media_entity_pipeline_start().
224 */
Sakari Ailusaf88be32012-01-11 06:25:15 -0300225__must_check int media_entity_pipeline_start(struct media_entity *entity,
226 struct media_pipeline *pipe)
Laurent Pincharte02188c2010-08-25 09:00:41 -0300227{
228 struct media_device *mdev = entity->parent;
229 struct media_entity_graph graph;
Sakari Ailusaf88be32012-01-11 06:25:15 -0300230 struct media_entity *entity_err = entity;
231 int ret;
Laurent Pincharte02188c2010-08-25 09:00:41 -0300232
233 mutex_lock(&mdev->graph_mutex);
234
235 media_entity_graph_walk_start(&graph, entity);
236
237 while ((entity = media_entity_graph_walk_next(&graph))) {
Mauro Carvalho Chehabef69ee12015-10-01 18:07:53 -0300238 DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
239 DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
Sakari Ailusaf88be32012-01-11 06:25:15 -0300240 unsigned int i;
241
Laurent Pincharte02188c2010-08-25 09:00:41 -0300242 entity->stream_count++;
243 WARN_ON(entity->pipe && entity->pipe != pipe);
244 entity->pipe = pipe;
Sakari Ailusaf88be32012-01-11 06:25:15 -0300245
246 /* Already streaming --- no need to check. */
247 if (entity->stream_count > 1)
248 continue;
249
250 if (!entity->ops || !entity->ops->link_validate)
251 continue;
252
Sakari Ailusde49c282013-10-13 08:00:26 -0300253 bitmap_zero(active, entity->num_pads);
254 bitmap_fill(has_no_links, entity->num_pads);
255
Sakari Ailusaf88be32012-01-11 06:25:15 -0300256 for (i = 0; i < entity->num_links; i++) {
257 struct media_link *link = &entity->links[i];
Sakari Ailusde49c282013-10-13 08:00:26 -0300258 struct media_pad *pad = link->sink->entity == entity
259 ? link->sink : link->source;
Sakari Ailusaf88be32012-01-11 06:25:15 -0300260
Sakari Ailusde49c282013-10-13 08:00:26 -0300261 /* Mark that a pad is connected by a link. */
262 bitmap_clear(has_no_links, pad->index, 1);
Sakari Ailusaf88be32012-01-11 06:25:15 -0300263
Sakari Ailusde49c282013-10-13 08:00:26 -0300264 /*
265 * Pads that either do not need to connect or
266 * are connected through an enabled link are
267 * fine.
268 */
269 if (!(pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||
270 link->flags & MEDIA_LNK_FL_ENABLED)
271 bitmap_set(active, pad->index, 1);
272
273 /*
274 * Link validation will only take place for
275 * sink ends of the link that are enabled.
276 */
277 if (link->sink != pad ||
278 !(link->flags & MEDIA_LNK_FL_ENABLED))
Sakari Ailusaf88be32012-01-11 06:25:15 -0300279 continue;
280
281 ret = entity->ops->link_validate(link);
Sakari Ailusfab9d302014-10-28 20:35:04 -0300282 if (ret < 0 && ret != -ENOIOCTLCMD) {
283 dev_dbg(entity->parent->dev,
284 "link validation failed for \"%s\":%u -> \"%s\":%u, error %d\n",
Sakari Ailus823ea2a2015-02-12 11:43:11 -0200285 link->source->entity->name,
286 link->source->index,
287 entity->name, link->sink->index, ret);
Sakari Ailusaf88be32012-01-11 06:25:15 -0300288 goto error;
Sakari Ailusfab9d302014-10-28 20:35:04 -0300289 }
Sakari Ailusaf88be32012-01-11 06:25:15 -0300290 }
Sakari Ailusde49c282013-10-13 08:00:26 -0300291
292 /* Either no links or validated links are fine. */
293 bitmap_or(active, active, has_no_links, entity->num_pads);
294
295 if (!bitmap_full(active, entity->num_pads)) {
296 ret = -EPIPE;
Sakari Ailusfab9d302014-10-28 20:35:04 -0300297 dev_dbg(entity->parent->dev,
298 "\"%s\":%u must be connected by an enabled link\n",
299 entity->name,
Sakari Ailus094f1ca2014-11-03 17:55:51 -0300300 (unsigned)find_first_zero_bit(
301 active, entity->num_pads));
Sakari Ailusde49c282013-10-13 08:00:26 -0300302 goto error;
303 }
Laurent Pincharte02188c2010-08-25 09:00:41 -0300304 }
305
306 mutex_unlock(&mdev->graph_mutex);
Sakari Ailusaf88be32012-01-11 06:25:15 -0300307
308 return 0;
309
310error:
311 /*
312 * Link validation on graph failed. We revert what we did and
313 * return the error.
314 */
315 media_entity_graph_walk_start(&graph, entity_err);
316
317 while ((entity_err = media_entity_graph_walk_next(&graph))) {
318 entity_err->stream_count--;
319 if (entity_err->stream_count == 0)
320 entity_err->pipe = NULL;
321
322 /*
323 * We haven't increased stream_count further than this
324 * so we quit here.
325 */
326 if (entity_err == entity)
327 break;
328 }
329
330 mutex_unlock(&mdev->graph_mutex);
331
332 return ret;
Laurent Pincharte02188c2010-08-25 09:00:41 -0300333}
334EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
335
336/**
337 * media_entity_pipeline_stop - Mark a pipeline as not streaming
338 * @entity: Starting entity
339 *
340 * Mark all entities connected to a given entity through enabled links, either
341 * directly or indirectly, as not streaming. The media_entity pipe field is
342 * reset to NULL.
343 *
344 * If multiple calls to media_entity_pipeline_start() have been made, the same
345 * number of calls to this function are required to mark the pipeline as not
346 * streaming.
347 */
348void media_entity_pipeline_stop(struct media_entity *entity)
349{
350 struct media_device *mdev = entity->parent;
351 struct media_entity_graph graph;
352
353 mutex_lock(&mdev->graph_mutex);
354
355 media_entity_graph_walk_start(&graph, entity);
356
357 while ((entity = media_entity_graph_walk_next(&graph))) {
358 entity->stream_count--;
359 if (entity->stream_count == 0)
360 entity->pipe = NULL;
361 }
362
363 mutex_unlock(&mdev->graph_mutex);
364}
365EXPORT_SYMBOL_GPL(media_entity_pipeline_stop);
366
367/* -----------------------------------------------------------------------------
Laurent Pinchart503c3d822010-03-07 15:04:59 -0300368 * Module use count
369 */
370
371/*
372 * media_entity_get - Get a reference to the parent module
373 * @entity: The entity
374 *
375 * Get a reference to the parent media device module.
376 *
377 * The function will return immediately if @entity is NULL.
378 *
379 * Return a pointer to the entity on success or NULL on failure.
380 */
381struct media_entity *media_entity_get(struct media_entity *entity)
382{
383 if (entity == NULL)
384 return NULL;
385
386 if (entity->parent->dev &&
387 !try_module_get(entity->parent->dev->driver->owner))
388 return NULL;
389
390 return entity;
391}
392EXPORT_SYMBOL_GPL(media_entity_get);
393
394/*
395 * media_entity_put - Release the reference to the parent module
396 * @entity: The entity
397 *
398 * Release the reference count acquired by media_entity_get().
399 *
400 * The function will return immediately if @entity is NULL.
401 */
402void media_entity_put(struct media_entity *entity)
403{
404 if (entity == NULL)
405 return;
406
407 if (entity->parent->dev)
408 module_put(entity->parent->dev->driver->owner);
409}
410EXPORT_SYMBOL_GPL(media_entity_put);
411
412/* -----------------------------------------------------------------------------
Sakari Ailusa5ccc482010-03-07 16:14:14 -0300413 * Links management
414 */
415
Laurent Pinchart53e269c2009-12-09 08:40:00 -0300416static struct media_link *media_entity_add_link(struct media_entity *entity)
417{
418 if (entity->num_links >= entity->max_links) {
419 struct media_link *links = entity->links;
420 unsigned int max_links = entity->max_links + 2;
421 unsigned int i;
422
423 links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL);
424 if (links == NULL)
425 return NULL;
426
427 for (i = 0; i < entity->num_links; i++)
428 links[i].reverse->reverse = &links[i];
429
430 entity->max_links = max_links;
431 entity->links = links;
432 }
433
434 return &entity->links[entity->num_links++];
435}
436
437int
438media_entity_create_link(struct media_entity *source, u16 source_pad,
439 struct media_entity *sink, u16 sink_pad, u32 flags)
440{
441 struct media_link *link;
442 struct media_link *backlink;
443
444 BUG_ON(source == NULL || sink == NULL);
445 BUG_ON(source_pad >= source->num_pads);
446 BUG_ON(sink_pad >= sink->num_pads);
447
448 link = media_entity_add_link(source);
449 if (link == NULL)
450 return -ENOMEM;
451
452 link->source = &source->pads[source_pad];
453 link->sink = &sink->pads[sink_pad];
454 link->flags = flags;
455
456 /* Create the backlink. Backlinks are used to help graph traversal and
457 * are not reported to userspace.
458 */
459 backlink = media_entity_add_link(sink);
460 if (backlink == NULL) {
461 source->num_links--;
462 return -ENOMEM;
463 }
464
465 backlink->source = &source->pads[source_pad];
466 backlink->sink = &sink->pads[sink_pad];
467 backlink->flags = flags;
468
469 link->reverse = backlink;
470 backlink->reverse = link;
471
472 sink->num_backlinks++;
473
474 return 0;
475}
476EXPORT_SYMBOL_GPL(media_entity_create_link);
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300477
Sylwester Nawrocki7349cec2013-05-09 08:29:32 -0300478void __media_entity_remove_links(struct media_entity *entity)
479{
480 unsigned int i;
481
482 for (i = 0; i < entity->num_links; i++) {
483 struct media_link *link = &entity->links[i];
484 struct media_entity *remote;
485 unsigned int r = 0;
486
487 if (link->source->entity == entity)
488 remote = link->sink->entity;
489 else
490 remote = link->source->entity;
491
492 while (r < remote->num_links) {
493 struct media_link *rlink = &remote->links[r];
494
495 if (rlink != link->reverse) {
496 r++;
497 continue;
498 }
499
500 if (link->source->entity == entity)
501 remote->num_backlinks--;
502
503 if (--remote->num_links == 0)
504 break;
505
506 /* Insert last entry in place of the dropped link. */
507 *rlink = remote->links[remote->num_links];
508 }
509 }
510
511 entity->num_links = 0;
512 entity->num_backlinks = 0;
513}
514EXPORT_SYMBOL_GPL(__media_entity_remove_links);
515
516void media_entity_remove_links(struct media_entity *entity)
517{
518 /* Do nothing if the entity is not registered. */
519 if (entity->parent == NULL)
520 return;
521
522 mutex_lock(&entity->parent->graph_mutex);
523 __media_entity_remove_links(entity);
524 mutex_unlock(&entity->parent->graph_mutex);
525}
526EXPORT_SYMBOL_GPL(media_entity_remove_links);
527
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300528static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
529{
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300530 int ret;
531
532 /* Notify both entities. */
533 ret = media_entity_call(link->source->entity, link_setup,
534 link->source, link->sink, flags);
535 if (ret < 0 && ret != -ENOIOCTLCMD)
536 return ret;
537
538 ret = media_entity_call(link->sink->entity, link_setup,
539 link->sink, link->source, flags);
540 if (ret < 0 && ret != -ENOIOCTLCMD) {
541 media_entity_call(link->source->entity, link_setup,
542 link->source, link->sink, link->flags);
543 return ret;
544 }
545
Laurent Pinchart7a6f0b22011-03-11 11:34:35 -0300546 link->flags = flags;
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300547 link->reverse->flags = link->flags;
548
549 return 0;
550}
551
552/**
553 * __media_entity_setup_link - Configure a media link
554 * @link: The link being configured
555 * @flags: Link configuration flags
556 *
557 * The bulk of link setup is handled by the two entities connected through the
558 * link. This function notifies both entities of the link configuration change.
559 *
560 * If the link is immutable or if the current and new configuration are
561 * identical, return immediately.
562 *
563 * The user is expected to hold link->source->parent->mutex. If not,
564 * media_entity_setup_link() should be used instead.
565 */
566int __media_entity_setup_link(struct media_link *link, u32 flags)
567{
Laurent Pinchart7a6f0b22011-03-11 11:34:35 -0300568 const u32 mask = MEDIA_LNK_FL_ENABLED;
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300569 struct media_device *mdev;
570 struct media_entity *source, *sink;
571 int ret = -EBUSY;
572
573 if (link == NULL)
574 return -EINVAL;
575
Laurent Pinchart7a6f0b22011-03-11 11:34:35 -0300576 /* The non-modifiable link flags must not be modified. */
577 if ((link->flags & ~mask) != (flags & ~mask))
578 return -EINVAL;
579
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300580 if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
581 return link->flags == flags ? 0 : -EINVAL;
582
583 if (link->flags == flags)
584 return 0;
585
586 source = link->source->entity;
587 sink = link->sink->entity;
588
Laurent Pincharte02188c2010-08-25 09:00:41 -0300589 if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
590 (source->stream_count || sink->stream_count))
591 return -EBUSY;
592
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300593 mdev = source->parent;
594
Sylwester Nawrocki813f5c02013-05-31 10:37:26 -0300595 if (mdev->link_notify) {
596 ret = mdev->link_notify(link, flags,
597 MEDIA_DEV_NOTIFY_PRE_LINK_CH);
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300598 if (ret < 0)
599 return ret;
600 }
601
602 ret = __media_entity_setup_link_notify(link, flags);
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300603
Sylwester Nawrocki813f5c02013-05-31 10:37:26 -0300604 if (mdev->link_notify)
605 mdev->link_notify(link, flags, MEDIA_DEV_NOTIFY_POST_LINK_CH);
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300606
607 return ret;
608}
609
610int media_entity_setup_link(struct media_link *link, u32 flags)
611{
612 int ret;
613
614 mutex_lock(&link->source->entity->parent->graph_mutex);
615 ret = __media_entity_setup_link(link, flags);
616 mutex_unlock(&link->source->entity->parent->graph_mutex);
617
618 return ret;
619}
620EXPORT_SYMBOL_GPL(media_entity_setup_link);
621
622/**
623 * media_entity_find_link - Find a link between two pads
624 * @source: Source pad
625 * @sink: Sink pad
626 *
627 * Return a pointer to the link between the two entities. If no such link
628 * exists, return NULL.
629 */
630struct media_link *
631media_entity_find_link(struct media_pad *source, struct media_pad *sink)
632{
633 struct media_link *link;
634 unsigned int i;
635
636 for (i = 0; i < source->entity->num_links; ++i) {
637 link = &source->entity->links[i];
638
639 if (link->source->entity == source->entity &&
640 link->source->index == source->index &&
641 link->sink->entity == sink->entity &&
642 link->sink->index == sink->index)
643 return link;
644 }
645
646 return NULL;
647}
648EXPORT_SYMBOL_GPL(media_entity_find_link);
649
650/**
Andrzej Hajda1bddf1b2013-06-03 05:16:13 -0300651 * media_entity_remote_pad - Find the pad at the remote end of a link
652 * @pad: Pad at the local end of the link
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300653 *
Andrzej Hajda1bddf1b2013-06-03 05:16:13 -0300654 * Search for a remote pad connected to the given pad by iterating over all
655 * links originating or terminating at that pad until an enabled link is found.
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300656 *
657 * Return a pointer to the pad at the remote end of the first found enabled
658 * link, or NULL if no enabled link has been found.
659 */
Andrzej Hajda1bddf1b2013-06-03 05:16:13 -0300660struct media_pad *media_entity_remote_pad(struct media_pad *pad)
Laurent Pinchart97548ed2009-12-09 08:40:03 -0300661{
662 unsigned int i;
663
664 for (i = 0; i < pad->entity->num_links; i++) {
665 struct media_link *link = &pad->entity->links[i];
666
667 if (!(link->flags & MEDIA_LNK_FL_ENABLED))
668 continue;
669
670 if (link->source == pad)
671 return link->sink;
672
673 if (link->sink == pad)
674 return link->source;
675 }
676
677 return NULL;
678
679}
Andrzej Hajda1bddf1b2013-06-03 05:16:13 -0300680EXPORT_SYMBOL_GPL(media_entity_remote_pad);