diff options
Diffstat (limited to 'Documentation/media-framework.txt')
| -rw-r--r-- | Documentation/media-framework.txt | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/Documentation/media-framework.txt b/Documentation/media-framework.txt index 3a0f879533c..f552a75c0e7 100644 --- a/Documentation/media-framework.txt +++ b/Documentation/media-framework.txt @@ -18,7 +18,7 @@ Abstract media device model Discovering a device internal topology, and configuring it at runtime, is one of the goals of the media framework. To achieve this, hardware devices are -modeled as an oriented graph of building blocks called entities connected +modelled as an oriented graph of building blocks called entities connected through pads. An entity is a basic media hardware building block. It can correspond to @@ -265,7 +265,7 @@ connected to another pad through an enabled link media_entity_find_link(struct media_pad *source, struct media_pad *sink); - media_entity_remote_source(struct media_pad *pad); + media_entity_remote_pad(struct media_pad *pad); Refer to the kerneldoc documentation for more information. @@ -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 of 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. |