]>
Commit | Line | Data |
---|---|---|
53e269c1 LP |
1 | /* |
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 | ||
5c7b25b9 | 23 | #include <linux/bitmap.h> |
53e269c1 LP |
24 | #include <linux/module.h> |
25 | #include <linux/slab.h> | |
26 | #include <media/media-entity.h> | |
503c3d82 | 27 | #include <media/media-device.h> |
53e269c1 LP |
28 | |
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 | */ | |
53 | int | |
54 | media_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 | } | |
80 | EXPORT_SYMBOL_GPL(media_entity_init); | |
81 | ||
82 | void | |
83 | media_entity_cleanup(struct media_entity *entity) | |
84 | { | |
85 | kfree(entity->links); | |
86 | } | |
87 | EXPORT_SYMBOL_GPL(media_entity_cleanup); | |
88 | ||
a5ccc48a SA |
89 | /* ----------------------------------------------------------------------------- |
90 | * Graph traversal | |
91 | */ | |
92 | ||
93 | static struct media_entity * | |
94 | media_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 */ | |
103 | static 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 | ||
115 | static 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 | ||
a5ccc48a SA |
125 | #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 | */ | |
138 | void 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; | |
5c7b25b9 LP |
143 | 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); | |
a5ccc48a SA |
149 | stack_push(graph, entity); |
150 | } | |
151 | EXPORT_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 | */ | |
165 | struct media_entity * | |
166 | media_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); | |
5c7b25b9 LP |
189 | if (WARN_ON(next->id >= MEDIA_ENTITY_ENUM_MAX_ID)) |
190 | return NULL; | |
a5ccc48a | 191 | |
5c7b25b9 LP |
192 | /* Has the entity already been visited? */ |
193 | if (__test_and_set_bit(next->id, graph->entities)) { | |
a5ccc48a SA |
194 | 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 | } | |
205 | EXPORT_SYMBOL_GPL(media_entity_graph_walk_next); | |
206 | ||
e02188c9 LP |
207 | /* ----------------------------------------------------------------------------- |
208 | * 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 | */ | |
af88be38 SA |
225 | __must_check int media_entity_pipeline_start(struct media_entity *entity, |
226 | struct media_pipeline *pipe) | |
e02188c9 LP |
227 | { |
228 | struct media_device *mdev = entity->parent; | |
229 | struct media_entity_graph graph; | |
af88be38 SA |
230 | struct media_entity *entity_err = entity; |
231 | int ret; | |
e02188c9 LP |
232 | |
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))) { | |
af88be38 SA |
238 | unsigned int i; |
239 | ||
e02188c9 LP |
240 | entity->stream_count++; |
241 | WARN_ON(entity->pipe && entity->pipe != pipe); | |
242 | entity->pipe = pipe; | |
af88be38 SA |
243 | |
244 | /* Already streaming --- no need to check. */ | |
245 | if (entity->stream_count > 1) | |
246 | continue; | |
247 | ||
248 | if (!entity->ops || !entity->ops->link_validate) | |
249 | continue; | |
250 | ||
251 | for (i = 0; i < entity->num_links; i++) { | |
252 | struct media_link *link = &entity->links[i]; | |
253 | ||
254 | /* Is this pad part of an enabled link? */ | |
255 | if (!(link->flags & MEDIA_LNK_FL_ENABLED)) | |
256 | continue; | |
257 | ||
258 | /* Are we the sink or not? */ | |
259 | if (link->sink->entity != entity) | |
260 | continue; | |
261 | ||
262 | ret = entity->ops->link_validate(link); | |
263 | if (ret < 0 && ret != -ENOIOCTLCMD) | |
264 | goto error; | |
265 | } | |
e02188c9 LP |
266 | } |
267 | ||
268 | mutex_unlock(&mdev->graph_mutex); | |
af88be38 SA |
269 | |
270 | return 0; | |
271 | ||
272 | error: | |
273 | /* | |
274 | * Link validation on graph failed. We revert what we did and | |
275 | * return the error. | |
276 | */ | |
277 | media_entity_graph_walk_start(&graph, entity_err); | |
278 | ||
279 | while ((entity_err = media_entity_graph_walk_next(&graph))) { | |
280 | entity_err->stream_count--; | |
281 | if (entity_err->stream_count == 0) | |
282 | entity_err->pipe = NULL; | |
283 | ||
284 | /* | |
285 | * We haven't increased stream_count further than this | |
286 | * so we quit here. | |
287 | */ | |
288 | if (entity_err == entity) | |
289 | break; | |
290 | } | |
291 | ||
292 | mutex_unlock(&mdev->graph_mutex); | |
293 | ||
294 | return ret; | |
e02188c9 LP |
295 | } |
296 | EXPORT_SYMBOL_GPL(media_entity_pipeline_start); | |
297 | ||
298 | /** | |
299 | * media_entity_pipeline_stop - Mark a pipeline as not streaming | |
300 | * @entity: Starting entity | |
301 | * | |
302 | * Mark all entities connected to a given entity through enabled links, either | |
303 | * directly or indirectly, as not streaming. The media_entity pipe field is | |
304 | * reset to NULL. | |
305 | * | |
306 | * If multiple calls to media_entity_pipeline_start() have been made, the same | |
307 | * number of calls to this function are required to mark the pipeline as not | |
308 | * streaming. | |
309 | */ | |
310 | void media_entity_pipeline_stop(struct media_entity *entity) | |
311 | { | |
312 | struct media_device *mdev = entity->parent; | |
313 | struct media_entity_graph graph; | |
314 | ||
315 | mutex_lock(&mdev->graph_mutex); | |
316 | ||
317 | media_entity_graph_walk_start(&graph, entity); | |
318 | ||
319 | while ((entity = media_entity_graph_walk_next(&graph))) { | |
320 | entity->stream_count--; | |
321 | if (entity->stream_count == 0) | |
322 | entity->pipe = NULL; | |
323 | } | |
324 | ||
325 | mutex_unlock(&mdev->graph_mutex); | |
326 | } | |
327 | EXPORT_SYMBOL_GPL(media_entity_pipeline_stop); | |
328 | ||
503c3d82 LP |
329 | /* ----------------------------------------------------------------------------- |
330 | * Module use count | |
331 | */ | |
332 | ||
333 | /* | |
334 | * media_entity_get - Get a reference to the parent module | |
335 | * @entity: The entity | |
336 | * | |
337 | * Get a reference to the parent media device module. | |
338 | * | |
339 | * The function will return immediately if @entity is NULL. | |
340 | * | |
341 | * Return a pointer to the entity on success or NULL on failure. | |
342 | */ | |
343 | struct media_entity *media_entity_get(struct media_entity *entity) | |
344 | { | |
345 | if (entity == NULL) | |
346 | return NULL; | |
347 | ||
348 | if (entity->parent->dev && | |
349 | !try_module_get(entity->parent->dev->driver->owner)) | |
350 | return NULL; | |
351 | ||
352 | return entity; | |
353 | } | |
354 | EXPORT_SYMBOL_GPL(media_entity_get); | |
355 | ||
356 | /* | |
357 | * media_entity_put - Release the reference to the parent module | |
358 | * @entity: The entity | |
359 | * | |
360 | * Release the reference count acquired by media_entity_get(). | |
361 | * | |
362 | * The function will return immediately if @entity is NULL. | |
363 | */ | |
364 | void media_entity_put(struct media_entity *entity) | |
365 | { | |
366 | if (entity == NULL) | |
367 | return; | |
368 | ||
369 | if (entity->parent->dev) | |
370 | module_put(entity->parent->dev->driver->owner); | |
371 | } | |
372 | EXPORT_SYMBOL_GPL(media_entity_put); | |
373 | ||
a5ccc48a SA |
374 | /* ----------------------------------------------------------------------------- |
375 | * Links management | |
376 | */ | |
377 | ||
53e269c1 LP |
378 | static struct media_link *media_entity_add_link(struct media_entity *entity) |
379 | { | |
380 | if (entity->num_links >= entity->max_links) { | |
381 | struct media_link *links = entity->links; | |
382 | unsigned int max_links = entity->max_links + 2; | |
383 | unsigned int i; | |
384 | ||
385 | links = krealloc(links, max_links * sizeof(*links), GFP_KERNEL); | |
386 | if (links == NULL) | |
387 | return NULL; | |
388 | ||
389 | for (i = 0; i < entity->num_links; i++) | |
390 | links[i].reverse->reverse = &links[i]; | |
391 | ||
392 | entity->max_links = max_links; | |
393 | entity->links = links; | |
394 | } | |
395 | ||
396 | return &entity->links[entity->num_links++]; | |
397 | } | |
398 | ||
399 | int | |
400 | media_entity_create_link(struct media_entity *source, u16 source_pad, | |
401 | struct media_entity *sink, u16 sink_pad, u32 flags) | |
402 | { | |
403 | struct media_link *link; | |
404 | struct media_link *backlink; | |
405 | ||
406 | BUG_ON(source == NULL || sink == NULL); | |
407 | BUG_ON(source_pad >= source->num_pads); | |
408 | BUG_ON(sink_pad >= sink->num_pads); | |
409 | ||
410 | link = media_entity_add_link(source); | |
411 | if (link == NULL) | |
412 | return -ENOMEM; | |
413 | ||
414 | link->source = &source->pads[source_pad]; | |
415 | link->sink = &sink->pads[sink_pad]; | |
416 | link->flags = flags; | |
417 | ||
418 | /* Create the backlink. Backlinks are used to help graph traversal and | |
419 | * are not reported to userspace. | |
420 | */ | |
421 | backlink = media_entity_add_link(sink); | |
422 | if (backlink == NULL) { | |
423 | source->num_links--; | |
424 | return -ENOMEM; | |
425 | } | |
426 | ||
427 | backlink->source = &source->pads[source_pad]; | |
428 | backlink->sink = &sink->pads[sink_pad]; | |
429 | backlink->flags = flags; | |
430 | ||
431 | link->reverse = backlink; | |
432 | backlink->reverse = link; | |
433 | ||
434 | sink->num_backlinks++; | |
435 | ||
436 | return 0; | |
437 | } | |
438 | EXPORT_SYMBOL_GPL(media_entity_create_link); | |
97548ed4 | 439 | |
7349cec1 SN |
440 | void __media_entity_remove_links(struct media_entity *entity) |
441 | { | |
442 | unsigned int i; | |
443 | ||
444 | for (i = 0; i < entity->num_links; i++) { | |
445 | struct media_link *link = &entity->links[i]; | |
446 | struct media_entity *remote; | |
447 | unsigned int r = 0; | |
448 | ||
449 | if (link->source->entity == entity) | |
450 | remote = link->sink->entity; | |
451 | else | |
452 | remote = link->source->entity; | |
453 | ||
454 | while (r < remote->num_links) { | |
455 | struct media_link *rlink = &remote->links[r]; | |
456 | ||
457 | if (rlink != link->reverse) { | |
458 | r++; | |
459 | continue; | |
460 | } | |
461 | ||
462 | if (link->source->entity == entity) | |
463 | remote->num_backlinks--; | |
464 | ||
465 | if (--remote->num_links == 0) | |
466 | break; | |
467 | ||
468 | /* Insert last entry in place of the dropped link. */ | |
469 | *rlink = remote->links[remote->num_links]; | |
470 | } | |
471 | } | |
472 | ||
473 | entity->num_links = 0; | |
474 | entity->num_backlinks = 0; | |
475 | } | |
476 | EXPORT_SYMBOL_GPL(__media_entity_remove_links); | |
477 | ||
478 | void media_entity_remove_links(struct media_entity *entity) | |
479 | { | |
480 | /* Do nothing if the entity is not registered. */ | |
481 | if (entity->parent == NULL) | |
482 | return; | |
483 | ||
484 | mutex_lock(&entity->parent->graph_mutex); | |
485 | __media_entity_remove_links(entity); | |
486 | mutex_unlock(&entity->parent->graph_mutex); | |
487 | } | |
488 | EXPORT_SYMBOL_GPL(media_entity_remove_links); | |
489 | ||
97548ed4 LP |
490 | static int __media_entity_setup_link_notify(struct media_link *link, u32 flags) |
491 | { | |
97548ed4 LP |
492 | int ret; |
493 | ||
494 | /* Notify both entities. */ | |
495 | ret = media_entity_call(link->source->entity, link_setup, | |
496 | link->source, link->sink, flags); | |
497 | if (ret < 0 && ret != -ENOIOCTLCMD) | |
498 | return ret; | |
499 | ||
500 | ret = media_entity_call(link->sink->entity, link_setup, | |
501 | link->sink, link->source, flags); | |
502 | if (ret < 0 && ret != -ENOIOCTLCMD) { | |
503 | media_entity_call(link->source->entity, link_setup, | |
504 | link->source, link->sink, link->flags); | |
505 | return ret; | |
506 | } | |
507 | ||
7a6f0b22 | 508 | link->flags = flags; |
97548ed4 LP |
509 | link->reverse->flags = link->flags; |
510 | ||
511 | return 0; | |
512 | } | |
513 | ||
514 | /** | |
515 | * __media_entity_setup_link - Configure a media link | |
516 | * @link: The link being configured | |
517 | * @flags: Link configuration flags | |
518 | * | |
519 | * The bulk of link setup is handled by the two entities connected through the | |
520 | * link. This function notifies both entities of the link configuration change. | |
521 | * | |
522 | * If the link is immutable or if the current and new configuration are | |
523 | * identical, return immediately. | |
524 | * | |
525 | * The user is expected to hold link->source->parent->mutex. If not, | |
526 | * media_entity_setup_link() should be used instead. | |
527 | */ | |
528 | int __media_entity_setup_link(struct media_link *link, u32 flags) | |
529 | { | |
7a6f0b22 | 530 | const u32 mask = MEDIA_LNK_FL_ENABLED; |
97548ed4 LP |
531 | struct media_device *mdev; |
532 | struct media_entity *source, *sink; | |
533 | int ret = -EBUSY; | |
534 | ||
535 | if (link == NULL) | |
536 | return -EINVAL; | |
537 | ||
7a6f0b22 LP |
538 | /* The non-modifiable link flags must not be modified. */ |
539 | if ((link->flags & ~mask) != (flags & ~mask)) | |
540 | return -EINVAL; | |
541 | ||
97548ed4 LP |
542 | if (link->flags & MEDIA_LNK_FL_IMMUTABLE) |
543 | return link->flags == flags ? 0 : -EINVAL; | |
544 | ||
545 | if (link->flags == flags) | |
546 | return 0; | |
547 | ||
548 | source = link->source->entity; | |
549 | sink = link->sink->entity; | |
550 | ||
e02188c9 LP |
551 | if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) && |
552 | (source->stream_count || sink->stream_count)) | |
553 | return -EBUSY; | |
554 | ||
97548ed4 LP |
555 | mdev = source->parent; |
556 | ||
813f5c0a SN |
557 | if (mdev->link_notify) { |
558 | ret = mdev->link_notify(link, flags, | |
559 | MEDIA_DEV_NOTIFY_PRE_LINK_CH); | |
97548ed4 LP |
560 | if (ret < 0) |
561 | return ret; | |
562 | } | |
563 | ||
564 | ret = __media_entity_setup_link_notify(link, flags); | |
97548ed4 | 565 | |
813f5c0a SN |
566 | if (mdev->link_notify) |
567 | mdev->link_notify(link, flags, MEDIA_DEV_NOTIFY_POST_LINK_CH); | |
97548ed4 LP |
568 | |
569 | return ret; | |
570 | } | |
571 | ||
572 | int media_entity_setup_link(struct media_link *link, u32 flags) | |
573 | { | |
574 | int ret; | |
575 | ||
576 | mutex_lock(&link->source->entity->parent->graph_mutex); | |
577 | ret = __media_entity_setup_link(link, flags); | |
578 | mutex_unlock(&link->source->entity->parent->graph_mutex); | |
579 | ||
580 | return ret; | |
581 | } | |
582 | EXPORT_SYMBOL_GPL(media_entity_setup_link); | |
583 | ||
584 | /** | |
585 | * media_entity_find_link - Find a link between two pads | |
586 | * @source: Source pad | |
587 | * @sink: Sink pad | |
588 | * | |
589 | * Return a pointer to the link between the two entities. If no such link | |
590 | * exists, return NULL. | |
591 | */ | |
592 | struct media_link * | |
593 | media_entity_find_link(struct media_pad *source, struct media_pad *sink) | |
594 | { | |
595 | struct media_link *link; | |
596 | unsigned int i; | |
597 | ||
598 | for (i = 0; i < source->entity->num_links; ++i) { | |
599 | link = &source->entity->links[i]; | |
600 | ||
601 | if (link->source->entity == source->entity && | |
602 | link->source->index == source->index && | |
603 | link->sink->entity == sink->entity && | |
604 | link->sink->index == sink->index) | |
605 | return link; | |
606 | } | |
607 | ||
608 | return NULL; | |
609 | } | |
610 | EXPORT_SYMBOL_GPL(media_entity_find_link); | |
611 | ||
612 | /** | |
1bddf1b3 AH |
613 | * media_entity_remote_pad - Find the pad at the remote end of a link |
614 | * @pad: Pad at the local end of the link | |
97548ed4 | 615 | * |
1bddf1b3 AH |
616 | * Search for a remote pad connected to the given pad by iterating over all |
617 | * links originating or terminating at that pad until an enabled link is found. | |
97548ed4 LP |
618 | * |
619 | * Return a pointer to the pad at the remote end of the first found enabled | |
620 | * link, or NULL if no enabled link has been found. | |
621 | */ | |
1bddf1b3 | 622 | struct media_pad *media_entity_remote_pad(struct media_pad *pad) |
97548ed4 LP |
623 | { |
624 | unsigned int i; | |
625 | ||
626 | for (i = 0; i < pad->entity->num_links; i++) { | |
627 | struct media_link *link = &pad->entity->links[i]; | |
628 | ||
629 | if (!(link->flags & MEDIA_LNK_FL_ENABLED)) | |
630 | continue; | |
631 | ||
632 | if (link->source == pad) | |
633 | return link->sink; | |
634 | ||
635 | if (link->sink == pad) | |
636 | return link->source; | |
637 | } | |
638 | ||
639 | return NULL; | |
640 | ||
641 | } | |
1bddf1b3 | 642 | EXPORT_SYMBOL_GPL(media_entity_remote_pad); |