drivers/media/media-entity.c

   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
  23 #include <linux/bitmap.h>
  24 #include <linux/module.h>
  25 #include <linux/slab.h>
  26 #include <media/media-entity.h>
  27 #include <media/media-device.h>
  28
  29 /**
  30  *  dev_dbg_obj - Prints in debug mode a change on some object
  31  *
  32  * @event_name: Name of the event to report. Could be __func__
  33  * @gobj:       Pointer to the object
  34  *
  35  * Enabled only if DEBUG or CONFIG_DYNAMIC_DEBUG. Otherwise, it
  36  * won't produce any code.
  37  */
  38 static inline const char *gobj_type(enum media_gobj_type type)
  39 {
  40         switch (type) {
  41         case MEDIA_GRAPH_ENTITY:
  42                 return "entity";
  43         case MEDIA_GRAPH_PAD:
  44                 return "pad";
  45         case MEDIA_GRAPH_LINK:
  46                 return "link";
  47         case MEDIA_GRAPH_INTF_DEVNODE:
  48                 return "intf-devnode";
  49         default:
  50                 return "unknown";
  51         }
  52 }
  53
  54 static inline const char *intf_type(struct media_interface *intf)
  55 {
  56         switch (intf->type) {
  57         case MEDIA_INTF_T_DVB_FE:
  58                 return "frontend";
  59         case MEDIA_INTF_T_DVB_DEMUX:
  60                 return "demux";
  61         case MEDIA_INTF_T_DVB_DVR:
  62                 return "DVR";
  63         case MEDIA_INTF_T_DVB_CA:
  64                 return  "CA";
  65         case MEDIA_INTF_T_DVB_NET:
  66                 return "dvbnet";
  67         case MEDIA_INTF_T_V4L_VIDEO:
  68                 return "video";
  69         case MEDIA_INTF_T_V4L_VBI:
  70                 return "vbi";
  71         case MEDIA_INTF_T_V4L_RADIO:
  72                 return "radio";
  73         case MEDIA_INTF_T_V4L_SUBDEV:
  74                 return "v4l2-subdev";
  75         case MEDIA_INTF_T_V4L_SWRADIO:
  76                 return "swradio";
  77         default:
  78                 return "unknown-intf";
  79         }
  80 };
  81
  82 static void dev_dbg_obj(const char *event_name,  struct media_gobj *gobj)
  83 {
  84 #if defined(DEBUG) || defined (CONFIG_DYNAMIC_DEBUG)
  85         switch (media_type(gobj)) {
  86         case MEDIA_GRAPH_ENTITY:
  87                 dev_dbg(gobj->mdev->dev,
  88                         "%s: id 0x%08x entity#%d: '%s'\n",
  89                         event_name, gobj->id, media_localid(gobj),
  90                         gobj_to_entity(gobj)->name);
  91                 break;
  92         case MEDIA_GRAPH_LINK:
  93         {
  94                 struct media_link *link = gobj_to_link(gobj);
  95
  96                 dev_dbg(gobj->mdev->dev,
  97                         "%s: id 0x%08x link#%d: '%s' %s#%d ==> '%s' %s#%d\n",
  98                         event_name, gobj->id, media_localid(gobj),
  99
 100                         link->source->entity->name,
 101                         gobj_type(media_type(&link->source->graph_obj)),
 102                         media_localid(&link->source->graph_obj),
 103
 104                         link->sink->entity->name,
 105                         gobj_type(media_type(&link->sink->graph_obj)),
 106                         media_localid(&link->sink->graph_obj));
 107                 break;
 108         }
 109         case MEDIA_GRAPH_PAD:
 110         {
 111                 struct media_pad *pad = gobj_to_pad(gobj);
 112
 113                 dev_dbg(gobj->mdev->dev,
 114                         "%s: id 0x%08x pad#%d: '%s':%d\n",
 115                         event_name, gobj->id, media_localid(gobj),
 116                         pad->entity->name, pad->index);
 117                 break;
 118         }
 119         case MEDIA_GRAPH_INTF_DEVNODE:
 120         {
 121                 struct media_interface *intf = gobj_to_intf(gobj);
 122                 struct media_intf_devnode *devnode = intf_to_devnode(intf);
 123
 124                 dev_dbg(gobj->mdev->dev,
 125                         "%s: id 0x%08x intf_devnode#%d: %s - major: %d, minor: %d\n",
 126                         event_name, gobj->id, media_localid(gobj),
 127                         intf_type(intf),
 128                         devnode->major, devnode->minor);
 129                 break;
 130         }
 131         }
 132 #endif
 133 }
 134
 135 /**
 136  *  media_gobj_init - Initialize a graph object
 137  *
 138  * @mdev:       Pointer to the media_device that contains the object
 139  * @type:       Type of the object
 140  * @gobj:       Pointer to the object
 141  *
 142  * This routine initializes the embedded struct media_gobj inside a
 143  * media graph object. It is called automatically if media_*_create()
 144  * calls are used. However, if the object (entity, link, pad, interface)
 145  * is embedded on some other object, this function should be called before
 146  * registering the object at the media controller.
 147  */
 148 void media_gobj_init(struct media_device *mdev,
 149                            enum media_gobj_type type,
 150                            struct media_gobj *gobj)
 151 {
 152         BUG_ON(!mdev);
 153
 154         gobj->mdev = mdev;
 155
 156         /* Create a per-type unique object ID */
 157         switch (type) {
 158         case MEDIA_GRAPH_ENTITY:
 159                 gobj->id = media_gobj_gen_id(type, ++mdev->entity_id);
 160                 break;
 161         case MEDIA_GRAPH_PAD:
 162                 gobj->id = media_gobj_gen_id(type, ++mdev->pad_id);
 163                 break;
 164         case MEDIA_GRAPH_LINK:
 165                 gobj->id = media_gobj_gen_id(type, ++mdev->link_id);
 166                 break;
 167         case MEDIA_GRAPH_INTF_DEVNODE:
 168                 gobj->id = media_gobj_gen_id(type, ++mdev->intf_devnode_id);
 169                 break;
 170         }
 171         dev_dbg_obj(__func__, gobj);
 172 }
 173
 174 /**
 175  *  media_gobj_remove - Stop using a graph object on a media device
 176  *
 177  * @graph_obj:  Pointer to the object
 178  *
 179  * This should be called at media_device_unregister_*() routines
 180  */
 181 void media_gobj_remove(struct media_gobj *gobj)
 182 {
 183         dev_dbg_obj(__func__, gobj);
 184 }
 185
 186 /**
 187  * media_entity_init - Initialize a media entity
 188  *
 189  * @num_pads: Total number of sink and source pads.
 190  * @pads: Array of 'num_pads' pads.
 191  *
 192  * The total number of pads is an intrinsic property of entities known by the
 193  * entity driver, while the total number of links depends on hardware design
 194  * and is an extrinsic property unknown to the entity driver. However, in most
 195  * use cases the number of links can safely be assumed to be equal to or
 196  * larger than the number of pads.
 197  *
 198  * For those reasons the links array can be preallocated based on the number
 199  * of pads and will be reallocated later if extra links need to be created.
 200  *
 201  * This function allocates a links array with enough space to hold at least
 202  * 'num_pads' elements. The media_entity::max_links field will be set to the
 203  * number of allocated elements.
 204  *
 205  * The pads array is managed by the entity driver and passed to
 206  * media_entity_init() where its pointer will be stored in the entity structure.
 207  */
 208 int
 209 media_entity_init(struct media_entity *entity, u16 num_pads,
 210                   struct media_pad *pads)
 211 {
 212         unsigned int i;
 213
 214         entity->group_id = 0;
 215         entity->num_links = 0;
 216         entity->num_backlinks = 0;
 217         entity->num_pads = num_pads;
 218         entity->pads = pads;
 219
 220         for (i = 0; i < num_pads; i++) {
 221                 pads[i].entity = entity;
 222                 pads[i].index = i;
 223         }
 224
 225         return 0;
 226 }
 227 EXPORT_SYMBOL_GPL(media_entity_init);
 228
 229 void
 230 media_entity_cleanup(struct media_entity *entity)
 231 {
 232         struct media_link *link, *tmp;
 233
 234         list_for_each_entry_safe(link, tmp, &entity->links, list) {
 235                 media_gobj_remove(&link->graph_obj);
 236                 list_del(&link->list);
 237                 kfree(link);
 238         }
 239 }
 240 EXPORT_SYMBOL_GPL(media_entity_cleanup);
 241
 242 /* -----------------------------------------------------------------------------
 243  * Graph traversal
 244  */
 245
 246 static struct media_entity *
 247 media_entity_other(struct media_entity *entity, struct media_link *link)
 248 {
 249         if (link->source->entity == entity)
 250                 return link->sink->entity;
 251         else
 252                 return link->source->entity;
 253 }
 254
 255 /* push an entity to traversal stack */
 256 static void stack_push(struct media_entity_graph *graph,
 257                        struct media_entity *entity)
 258 {
 259         if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
 260                 WARN_ON(1);
 261                 return;
 262         }
 263         graph->top++;
 264         graph->stack[graph->top].link = (&entity->links)->next;
 265         graph->stack[graph->top].entity = entity;
 266 }
 267
 268 static struct media_entity *stack_pop(struct media_entity_graph *graph)
 269 {
 270         struct media_entity *entity;
 271
 272         entity = graph->stack[graph->top].entity;
 273         graph->top--;
 274
 275         return entity;
 276 }
 277
 278 #define link_top(en)    ((en)->stack[(en)->top].link)
 279 #define stack_top(en)   ((en)->stack[(en)->top].entity)
 280
 281 /**
 282  * media_entity_graph_walk_start - Start walking the media graph at a given entity
 283  * @graph: Media graph structure that will be used to walk the graph
 284  * @entity: Starting entity
 285  *
 286  * This function initializes the graph traversal structure to walk the entities
 287  * graph starting at the given entity. The traversal structure must not be
 288  * modified by the caller during graph traversal. When done the structure can
 289  * safely be freed.
 290  */
 291 void media_entity_graph_walk_start(struct media_entity_graph *graph,
 292                                    struct media_entity *entity)
 293 {
 294         graph->top = 0;
 295         graph->stack[graph->top].entity = NULL;
 296         bitmap_zero(graph->entities, MEDIA_ENTITY_ENUM_MAX_ID);
 297
 298         if (WARN_ON(media_entity_id(entity) >= MEDIA_ENTITY_ENUM_MAX_ID))
 299                 return;
 300
 301         __set_bit(media_entity_id(entity), graph->entities);
 302         stack_push(graph, entity);
 303 }
 304 EXPORT_SYMBOL_GPL(media_entity_graph_walk_start);
 305
 306
 307 /**
 308  * media_entity_graph_walk_next - Get the next entity in the graph
 309  * @graph: Media graph structure
 310  *
 311  * Perform a depth-first traversal of the given media entities graph.
 312  *
 313  * The graph structure must have been previously initialized with a call to
 314  * media_entity_graph_walk_start().
 315  *
 316  * Return the next entity in the graph or NULL if the whole graph have been
 317  * traversed.
 318  */
 319 struct media_entity *
 320 media_entity_graph_walk_next(struct media_entity_graph *graph)
 321 {
 322         if (stack_top(graph) == NULL)
 323                 return NULL;
 324
 325         /*
 326          * Depth first search. Push entity to stack and continue from
 327          * top of the stack until no more entities on the level can be
 328          * found.
 329          */
 330         while (link_top(graph) != &(stack_top(graph)->links)) {
 331                 struct media_entity *entity = stack_top(graph);
 332                 struct media_link *link;
 333                 struct media_entity *next;
 334
 335                 link = list_entry(link_top(graph), typeof(*link), list);
 336
 337                 /* The link is not enabled so we do not follow. */
 338                 if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
 339                         link_top(graph) = link_top(graph)->next;
 340                         continue;
 341                 }
 342
 343                 /* Get the entity in the other end of the link . */
 344                 next = media_entity_other(entity, link);
 345                 if (WARN_ON(media_entity_id(next) >= MEDIA_ENTITY_ENUM_MAX_ID))
 346                         return NULL;
 347
 348                 /* Has the entity already been visited? */
 349                 if (__test_and_set_bit(media_entity_id(next), graph->entities)) {
 350                         link_top(graph) = link_top(graph)->next;
 351                         continue;
 352                 }
 353
 354                 /* Push the new entity to stack and start over. */
 355                 link_top(graph) = link_top(graph)->next;
 356                 stack_push(graph, next);
 357         }
 358
 359         return stack_pop(graph);
 360 }
 361 EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
 362
 363 /* -----------------------------------------------------------------------------
 364  * Pipeline management
 365  */
 366
 367 /**
 368  * media_entity_pipeline_start - Mark a pipeline as streaming
 369  * @entity: Starting entity
 370  * @pipe: Media pipeline to be assigned to all entities in the pipeline.
 371  *
 372  * Mark all entities connected to a given entity through enabled links, either
 373  * directly or indirectly, as streaming. The given pipeline object is assigned to
 374  * every entity in the pipeline and stored in the media_entity pipe field.
 375  *
 376  * Calls to this function can be nested, in which case the same number of
 377  * media_entity_pipeline_stop() calls will be required to stop streaming. The
 378  * pipeline pointer must be identical for all nested calls to
 379  * media_entity_pipeline_start().
 380  */
 381 __must_check int media_entity_pipeline_start(struct media_entity *entity,
 382                                              struct media_pipeline *pipe)
 383 {
 384         struct media_device *mdev = entity->graph_obj.mdev;
 385         struct media_entity_graph graph;
 386         struct media_entity *entity_err = entity;
 387         struct media_link *link;
 388         int ret;
 389
 390         mutex_lock(&mdev->graph_mutex);
 391
 392         media_entity_graph_walk_start(&graph, entity);
 393
 394         while ((entity = media_entity_graph_walk_next(&graph))) {
 395                 DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS);
 396                 DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS);
 397
 398                 entity->stream_count++;
 399                 WARN_ON(entity->pipe && entity->pipe != pipe);
 400                 entity->pipe = pipe;
 401
 402                 /* Already streaming --- no need to check. */
 403                 if (entity->stream_count > 1)
 404                         continue;
 405
 406                 if (!entity->ops || !entity->ops->link_validate)
 407                         continue;
 408
 409                 bitmap_zero(active, entity->num_pads);
 410                 bitmap_fill(has_no_links, entity->num_pads);
 411
 412                 list_for_each_entry(link, &entity->links, list) {
 413                         struct media_pad *pad = link->sink->entity == entity
 414                                                 ? link->sink : link->source;
 415
 416                         /* Mark that a pad is connected by a link. */
 417                         bitmap_clear(has_no_links, pad->index, 1);
 418
 419                         /*
 420                          * Pads that either do not need to connect or
 421                          * are connected through an enabled link are
 422                          * fine.
 423                          */
 424                         if (!(pad->flags & MEDIA_PAD_FL_MUST_CONNECT) ||
 425                             link->flags & MEDIA_LNK_FL_ENABLED)
 426                                 bitmap_set(active, pad->index, 1);
 427
 428                         /*
 429                          * Link validation will only take place for
 430                          * sink ends of the link that are enabled.
 431                          */
 432                         if (link->sink != pad ||
 433                             !(link->flags & MEDIA_LNK_FL_ENABLED))
 434                                 continue;
 435
 436                         ret = entity->ops->link_validate(link);
 437                         if (ret < 0 && ret != -ENOIOCTLCMD) {
 438                                 dev_dbg(entity->graph_obj.mdev->dev,
 439                                         "link validation failed for \"%s\":%u -> \"%s\":%u, error %d\n",
 440                                         link->source->entity->name,
 441                                         link->source->index,
 442                                         entity->name, link->sink->index, ret);
 443                                 goto error;
 444                         }
 445                 }
 446
 447                 /* Either no links or validated links are fine. */
 448                 bitmap_or(active, active, has_no_links, entity->num_pads);
 449
 450                 if (!bitmap_full(active, entity->num_pads)) {
 451                         ret = -EPIPE;
 452                         dev_dbg(entity->graph_obj.mdev->dev,
 453                                 "\"%s\":%u must be connected by an enabled link\n",
 454                                 entity->name,
 455                                 (unsigned)find_first_zero_bit(
 456                                         active, entity->num_pads));
 457                         goto error;
 458                 }
 459         }
 460
 461         mutex_unlock(&mdev->graph_mutex);
 462
 463         return 0;
 464
 465 error:
 466         /*
 467          * Link validation on graph failed. We revert what we did and
 468          * return the error.
 469          */
 470         media_entity_graph_walk_start(&graph, entity_err);
 471
 472         while ((entity_err = media_entity_graph_walk_next(&graph))) {
 473                 entity_err->stream_count--;
 474                 if (entity_err->stream_count == 0)
 475                         entity_err->pipe = NULL;
 476
 477                 /*
 478                  * We haven't increased stream_count further than this
 479                  * so we quit here.
 480                  */
 481                 if (entity_err == entity)
 482                         break;
 483         }
 484
 485         mutex_unlock(&mdev->graph_mutex);
 486
 487         return ret;
 488 }
 489 EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
 490
 491 /**
 492  * media_entity_pipeline_stop - Mark a pipeline as not streaming
 493  * @entity: Starting entity
 494  *
 495  * Mark all entities connected to a given entity through enabled links, either
 496  * directly or indirectly, as not streaming. The media_entity pipe field is
 497  * reset to NULL.
 498  *
 499  * If multiple calls to media_entity_pipeline_start() have been made, the same
 500  * number of calls to this function are required to mark the pipeline as not
 501  * streaming.
 502  */
 503 void media_entity_pipeline_stop(struct media_entity *entity)
 504 {
 505         struct media_device *mdev = entity->graph_obj.mdev;
 506         struct media_entity_graph graph;
 507
 508         mutex_lock(&mdev->graph_mutex);
 509
 510         media_entity_graph_walk_start(&graph, entity);
 511
 512         while ((entity = media_entity_graph_walk_next(&graph))) {
 513                 entity->stream_count--;
 514                 if (entity->stream_count == 0)
 515                         entity->pipe = NULL;
 516         }
 517
 518         mutex_unlock(&mdev->graph_mutex);
 519 }
 520 EXPORT_SYMBOL_GPL(media_entity_pipeline_stop);
 521
 522 /* -----------------------------------------------------------------------------
 523  * Module use count
 524  */
 525
 526 /*
 527  * media_entity_get - Get a reference to the parent module
 528  * @entity: The entity
 529  *
 530  * Get a reference to the parent media device module.
 531  *
 532  * The function will return immediately if @entity is NULL.
 533  *
 534  * Return a pointer to the entity on success or NULL on failure.
 535  */
 536 struct media_entity *media_entity_get(struct media_entity *entity)
 537 {
 538         if (entity == NULL)
 539                 return NULL;
 540
 541         if (entity->graph_obj.mdev->dev &&
 542             !try_module_get(entity->graph_obj.mdev->dev->driver->owner))
 543                 return NULL;
 544
 545         return entity;
 546 }
 547 EXPORT_SYMBOL_GPL(media_entity_get);
 548
 549 /*
 550  * media_entity_put - Release the reference to the parent module
 551  * @entity: The entity
 552  *
 553  * Release the reference count acquired by media_entity_get().
 554  *
 555  * The function will return immediately if @entity is NULL.
 556  */
 557 void media_entity_put(struct media_entity *entity)
 558 {
 559         if (entity == NULL)
 560                 return;
 561
 562         if (entity->graph_obj.mdev->dev)
 563                 module_put(entity->graph_obj.mdev->dev->driver->owner);
 564 }
 565 EXPORT_SYMBOL_GPL(media_entity_put);
 566
 567 /* -----------------------------------------------------------------------------
 568  * Links management
 569  */
 570
 571 static struct media_link *media_entity_add_link(struct media_entity *entity)
 572 {
 573         struct media_link *link;
 574
 575         link = kzalloc(sizeof(*link), GFP_KERNEL);
 576         if (link == NULL)
 577                 return NULL;
 578
 579         list_add_tail(&link->list, &entity->links);
 580
 581         return link;
 582 }
 583
 584 static void __media_entity_remove_link(struct media_entity *entity,
 585                                        struct media_link *link);
 586
 587 int
 588 media_create_pad_link(struct media_entity *source, u16 source_pad,
 589                          struct media_entity *sink, u16 sink_pad, u32 flags)
 590 {
 591         struct media_link *link;
 592         struct media_link *backlink;
 593
 594         BUG_ON(source == NULL || sink == NULL);
 595         BUG_ON(source_pad >= source->num_pads);
 596         BUG_ON(sink_pad >= sink->num_pads);
 597
 598         link = media_entity_add_link(source);
 599         if (link == NULL)
 600                 return -ENOMEM;
 601
 602         link->source = &source->pads[source_pad];
 603         link->sink = &sink->pads[sink_pad];
 604         link->flags = flags;
 605
 606         /* Initialize graph object embedded at the new link */
 607         media_gobj_init(source->graph_obj.mdev, MEDIA_GRAPH_LINK,
 608                         &link->graph_obj);
 609
 610         /* Create the backlink. Backlinks are used to help graph traversal and
 611          * are not reported to userspace.
 612          */
 613         backlink = media_entity_add_link(sink);
 614         if (backlink == NULL) {
 615                 __media_entity_remove_link(source, link);
 616                 return -ENOMEM;
 617         }
 618
 619         backlink->source = &source->pads[source_pad];
 620         backlink->sink = &sink->pads[sink_pad];
 621         backlink->flags = flags;
 622
 623         /* Initialize graph object embedded at the new link */
 624         media_gobj_init(sink->graph_obj.mdev, MEDIA_GRAPH_LINK,
 625                         &backlink->graph_obj);
 626
 627         link->reverse = backlink;
 628         backlink->reverse = link;
 629
 630         sink->num_backlinks++;
 631         sink->num_links++;
 632         source->num_links++;
 633
 634         return 0;
 635 }
 636 EXPORT_SYMBOL_GPL(media_create_pad_link);
 637
 638 static void __media_entity_remove_link(struct media_entity *entity,
 639                                        struct media_link *link)
 640 {
 641         struct media_link *rlink, *tmp;
 642         struct media_entity *remote;
 643         unsigned int r = 0;
 644
 645         if (link->source->entity == entity)
 646                 remote = link->sink->entity;
 647         else
 648                 remote = link->source->entity;
 649
 650         list_for_each_entry_safe(rlink, tmp, &remote->links, list) {
 651                 if (rlink != link->reverse) {
 652                         r++;
 653                         continue;
 654                 }
 655
 656                 if (link->source->entity == entity)
 657                         remote->num_backlinks--;
 658
 659                 if (--remote->num_links == 0)
 660                         break;
 661
 662                 /* Remove the remote link */
 663                 list_del(&rlink->list);
 664                 kfree(rlink);
 665         }
 666         list_del(&link->list);
 667         kfree(link);
 668 }
 669
 670 void __media_entity_remove_links(struct media_entity *entity)
 671 {
 672         struct media_link *link, *tmp;
 673
 674         list_for_each_entry_safe(link, tmp, &entity->links, list)
 675                 __media_entity_remove_link(entity, link);
 676
 677         entity->num_links = 0;
 678         entity->num_backlinks = 0;
 679 }
 680 EXPORT_SYMBOL_GPL(__media_entity_remove_links);
 681
 682 void media_entity_remove_links(struct media_entity *entity)
 683 {
 684         /* Do nothing if the entity is not registered. */
 685         if (entity->graph_obj.mdev == NULL)
 686                 return;
 687
 688         mutex_lock(&entity->graph_obj.mdev->graph_mutex);
 689         __media_entity_remove_links(entity);
 690         mutex_unlock(&entity->graph_obj.mdev->graph_mutex);
 691 }
 692 EXPORT_SYMBOL_GPL(media_entity_remove_links);
 693
 694 static int __media_entity_setup_link_notify(struct media_link *link, u32 flags)
 695 {
 696         int ret;
 697
 698         /* Notify both entities. */
 699         ret = media_entity_call(link->source->entity, link_setup,
 700                                 link->source, link->sink, flags);
 701         if (ret < 0 && ret != -ENOIOCTLCMD)
 702                 return ret;
 703
 704         ret = media_entity_call(link->sink->entity, link_setup,
 705                                 link->sink, link->source, flags);
 706         if (ret < 0 && ret != -ENOIOCTLCMD) {
 707                 media_entity_call(link->source->entity, link_setup,
 708                                   link->source, link->sink, link->flags);
 709                 return ret;
 710         }
 711
 712         link->flags = flags;
 713         link->reverse->flags = link->flags;
 714
 715         return 0;
 716 }
 717
 718 /**
 719  * __media_entity_setup_link - Configure a media link
 720  * @link: The link being configured
 721  * @flags: Link configuration flags
 722  *
 723  * The bulk of link setup is handled by the two entities connected through the
 724  * link. This function notifies both entities of the link configuration change.
 725  *
 726  * If the link is immutable or if the current and new configuration are
 727  * identical, return immediately.
 728  *
 729  * The user is expected to hold link->source->parent->mutex. If not,
 730  * media_entity_setup_link() should be used instead.
 731  */
 732 int __media_entity_setup_link(struct media_link *link, u32 flags)
 733 {
 734         const u32 mask = MEDIA_LNK_FL_ENABLED;
 735         struct media_device *mdev;
 736         struct media_entity *source, *sink;
 737         int ret = -EBUSY;
 738
 739         if (link == NULL)
 740                 return -EINVAL;
 741
 742         /* The non-modifiable link flags must not be modified. */
 743         if ((link->flags & ~mask) != (flags & ~mask))
 744                 return -EINVAL;
 745
 746         if (link->flags & MEDIA_LNK_FL_IMMUTABLE)
 747                 return link->flags == flags ? 0 : -EINVAL;
 748
 749         if (link->flags == flags)
 750                 return 0;
 751
 752         source = link->source->entity;
 753         sink = link->sink->entity;
 754
 755         if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
 756             (source->stream_count || sink->stream_count))
 757                 return -EBUSY;
 758
 759         mdev = source->graph_obj.mdev;
 760
 761         if (mdev->link_notify) {
 762                 ret = mdev->link_notify(link, flags,
 763                                         MEDIA_DEV_NOTIFY_PRE_LINK_CH);
 764                 if (ret < 0)
 765                         return ret;
 766         }
 767
 768         ret = __media_entity_setup_link_notify(link, flags);
 769
 770         if (mdev->link_notify)
 771                 mdev->link_notify(link, flags, MEDIA_DEV_NOTIFY_POST_LINK_CH);
 772
 773         return ret;
 774 }
 775
 776 int media_entity_setup_link(struct media_link *link, u32 flags)
 777 {
 778         int ret;
 779
 780         mutex_lock(&link->source->entity->graph_obj.mdev->graph_mutex);
 781         ret = __media_entity_setup_link(link, flags);
 782         mutex_unlock(&link->source->entity->graph_obj.mdev->graph_mutex);
 783
 784         return ret;
 785 }
 786 EXPORT_SYMBOL_GPL(media_entity_setup_link);
 787
 788 /**
 789  * media_entity_find_link - Find a link between two pads
 790  * @source: Source pad
 791  * @sink: Sink pad
 792  *
 793  * Return a pointer to the link between the two entities. If no such link
 794  * exists, return NULL.
 795  */
 796 struct media_link *
 797 media_entity_find_link(struct media_pad *source, struct media_pad *sink)
 798 {
 799         struct media_link *link;
 800
 801         list_for_each_entry(link, &source->entity->links, list) {
 802                 if (link->source->entity == source->entity &&
 803                     link->source->index == source->index &&
 804                     link->sink->entity == sink->entity &&
 805                     link->sink->index == sink->index)
 806                         return link;
 807         }
 808
 809         return NULL;
 810 }
 811 EXPORT_SYMBOL_GPL(media_entity_find_link);
 812
 813 /**
 814  * media_entity_remote_pad - Find the pad at the remote end of a link
 815  * @pad: Pad at the local end of the link
 816  *
 817  * Search for a remote pad connected to the given pad by iterating over all
 818  * links originating or terminating at that pad until an enabled link is found.
 819  *
 820  * Return a pointer to the pad at the remote end of the first found enabled
 821  * link, or NULL if no enabled link has been found.
 822  */
 823 struct media_pad *media_entity_remote_pad(struct media_pad *pad)
 824 {
 825         struct media_link *link;
 826
 827         list_for_each_entry(link, &pad->entity->links, list) {
 828                 if (!(link->flags & MEDIA_LNK_FL_ENABLED))
 829                         continue;
 830
 831                 if (link->source == pad)
 832                         return link->sink;
 833
 834                 if (link->sink == pad)
 835                         return link->source;
 836         }
 837
 838         return NULL;
 839
 840 }
 841 EXPORT_SYMBOL_GPL(media_entity_remote_pad);
 842
 843
 844 /* Functions related to the media interface via device nodes */
 845
 846 struct media_intf_devnode *media_devnode_create(struct media_device *mdev,
 847                                                 u32 type, u32 flags,
 848                                                 u32 major, u32 minor,
 849                                                 gfp_t gfp_flags)
 850 {
 851         struct media_intf_devnode *devnode;
 852         struct media_interface *intf;
 853
 854         devnode = kzalloc(sizeof(*devnode), gfp_flags);
 855         if (!devnode)
 856                 return NULL;
 857
 858         intf = &devnode->intf;
 859
 860         intf->type = type;
 861         intf->flags = flags;
 862
 863         devnode->major = major;
 864         devnode->minor = minor;
 865
 866         media_gobj_init(mdev, MEDIA_GRAPH_INTF_DEVNODE,
 867                        &devnode->intf.graph_obj);
 868
 869         return devnode;
 870 }
 871 EXPORT_SYMBOL_GPL(media_devnode_create);
 872
 873 void media_devnode_remove(struct media_intf_devnode *devnode)
 874 {
 875         media_gobj_remove(&devnode->intf.graph_obj);
 876         kfree(devnode);
 877 }
 878 EXPORT_SYMBOL_GPL(media_devnode_remove);