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Diffstat (limited to 'Documentation/media-framework.txt')
| -rw-r--r-- | Documentation/media-framework.txt | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/Documentation/media-framework.txt b/Documentation/media-framework.txt index 3a0f879533c..80287541387 100644 --- a/Documentation/media-framework.txt +++ b/Documentation/media-framework.txt @@ -335,6 +335,9 @@ the media_entity pipe field. Calls to media_entity_pipeline_start() can be nested. The pipeline pointer must be identical for all nested calls to the function. +media_entity_pipeline_start() may return an error. In that case, it will +clean up any the changes it did by itself. + When stopping the stream, drivers must notify the entities with media_entity_pipeline_stop(struct media_entity *entity); @@ -351,3 +354,19 @@ If other operations need to be disallowed on streaming entities (such as changing entities configuration parameters) drivers can explicitly check the media_entity stream_count field to find out if an entity is streaming. This operation must be done with the media_device graph_mutex held. + + +Link validation +--------------- + +Link validation is performed by media_entity_pipeline_start() for any +entity which has sink pads in the pipeline. The +media_entity::link_validate() callback is used for that purpose. In +link_validate() callback, entity driver should check that the properties of +the source pad of the connected entity and its own sink pad match. It is up +to the type of the entity (and in the end, the properties of the hardware) +what matching actually means. + +Subsystems should facilitate link validation by providing subsystem specific +helper functions to provide easy access for commonly needed information, and +in the end provide a way to use driver-specific callbacks. |