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authorLaurent Pinchart <laurent.pinchart@ideasonboard.com>2010-08-25 09:00:41 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-03-22 04:53:17 -0300
commite02188c90f6ef61f0844c42508fe603c5d4fa42b (patch)
tree7b0ff940b37ba6bf53c7cea7fadbb697ec2d156a /drivers/media/media-entity.c
parent97548ed4c4661502cdfd1aabd5d3876fa4f5cc2e (diff)
downloadlinux-linaro-stable-e02188c90f6ef61f0844c42508fe603c5d4fa42b.tar.gz
[media] media: Pipelines and media streams
Drivers often need to associate pipeline objects to entities, and to take stream state into account when configuring entities and links. The pipeline API helps drivers manage that information. When starting streaming, drivers call media_entity_pipeline_start(). The function marks all entities connected to the given entity through enabled links, either directly or indirectly, as streaming. Similarly, when stopping the stream, drivers call media_entity_pipeline_stop(). The media_entity_pipeline_start() function takes a pointer to a media pipeline and stores it in every entity in the graph. Drivers should embed the media_pipeline structure in higher-level pipeline structures and can then access the pipeline through the media_entity structure. Link configuration will fail with -EBUSY by default if either end of the link is a streaming entity, unless the link is marked with the MEDIA_LNK_FL_DYNAMIC flag. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers/media/media-entity.c')
-rw-r--r--drivers/media/media-entity.c73
1 files changed, 73 insertions, 0 deletions
diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
index 6795c920d460..23640ed44d85 100644
--- a/drivers/media/media-entity.c
+++ b/drivers/media/media-entity.c
@@ -197,6 +197,75 @@ media_entity_graph_walk_next(struct media_entity_graph *graph)
EXPORT_SYMBOL_GPL(media_entity_graph_walk_next);
/* -----------------------------------------------------------------------------
+ * Pipeline management
+ */
+
+/**
+ * media_entity_pipeline_start - Mark a pipeline as streaming
+ * @entity: Starting entity
+ * @pipe: Media pipeline to be assigned to all entities in the pipeline.
+ *
+ * Mark all entities connected to a given entity through enabled links, either
+ * directly or indirectly, as streaming. The given pipeline object is assigned to
+ * every entity in the pipeline and stored in the media_entity pipe field.
+ *
+ * Calls to this function can be nested, in which case the same number of
+ * media_entity_pipeline_stop() calls will be required to stop streaming. The
+ * pipeline pointer must be identical for all nested calls to
+ * media_entity_pipeline_start().
+ */
+void media_entity_pipeline_start(struct media_entity *entity,
+ struct media_pipeline *pipe)
+{
+ struct media_device *mdev = entity->parent;
+ struct media_entity_graph graph;
+
+ mutex_lock(&mdev->graph_mutex);
+
+ media_entity_graph_walk_start(&graph, entity);
+
+ while ((entity = media_entity_graph_walk_next(&graph))) {
+ entity->stream_count++;
+ WARN_ON(entity->pipe && entity->pipe != pipe);
+ entity->pipe = pipe;
+ }
+
+ mutex_unlock(&mdev->graph_mutex);
+}
+EXPORT_SYMBOL_GPL(media_entity_pipeline_start);
+
+/**
+ * media_entity_pipeline_stop - Mark a pipeline as not streaming
+ * @entity: Starting entity
+ *
+ * Mark all entities connected to a given entity through enabled links, either
+ * directly or indirectly, as not streaming. The media_entity pipe field is
+ * reset to NULL.
+ *
+ * If multiple calls to media_entity_pipeline_start() have been made, the same
+ * number of calls to this function are required to mark the pipeline as not
+ * streaming.
+ */
+void media_entity_pipeline_stop(struct media_entity *entity)
+{
+ struct media_device *mdev = entity->parent;
+ struct media_entity_graph graph;
+
+ mutex_lock(&mdev->graph_mutex);
+
+ media_entity_graph_walk_start(&graph, entity);
+
+ while ((entity = media_entity_graph_walk_next(&graph))) {
+ entity->stream_count--;
+ if (entity->stream_count == 0)
+ entity->pipe = NULL;
+ }
+
+ mutex_unlock(&mdev->graph_mutex);
+}
+EXPORT_SYMBOL_GPL(media_entity_pipeline_stop);
+
+/* -----------------------------------------------------------------------------
* Module use count
*/
@@ -364,6 +433,10 @@ int __media_entity_setup_link(struct media_link *link, u32 flags)
source = link->source->entity;
sink = link->sink->entity;
+ if (!(link->flags & MEDIA_LNK_FL_DYNAMIC) &&
+ (source->stream_count || sink->stream_count))
+ return -EBUSY;
+
mdev = source->parent;
if ((flags & MEDIA_LNK_FL_ENABLED) && mdev->link_notify) {