media: mc: entity: add alloc variant of pipeline_start

Add new variant of media_pipeline_start(), media_pipeline_alloc_start().

media_pipeline_alloc_start() can be used by drivers that do not need to
extend the media_pipeline. The function will either use the pipeline
already associated with the entity, if such exists, or allocate a new
pipeline.

When media_pipeline_stop() is called and the pipeline's use count drops
to zero, the pipeline is automatically freed.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

2 files changed, 29 insertions, 0 deletions

diff --git a/include/media/media-entity.h b/include/media/media-entity.h
index aaf276f765cf..a77933afaa48 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -100,10 +100,12 @@ struct media_graph {
 /**
  * struct media_pipeline - Media pipeline related information
  *
+ * @allocated:		Media pipeline allocated and freed by the framework
  * @start_count:	Media pipeline start - stop count
  * @graph:		Media graph walk during pipeline start / stop
  */
 struct media_pipeline {
+	bool allocated;
 	int start_count;
 	struct media_graph graph;
 };
@@ -1093,6 +1095,19 @@ void media_pipeline_stop(struct media_entity *entity);
 void __media_pipeline_stop(struct media_entity *entity);
 
 /**
+ * media_pipeline_alloc_start - Mark a pipeline as streaming
+ * @entity: Starting entity
+ *
+ * media_pipeline_alloc_start() is similar to media_pipeline_start() but instead
+ * of working on a given pipeline the function will use an existing pipeline if
+ * the entity is already part of a pipeline, or allocate a new pipeline.
+ *
+ * Calls to media_pipeline_alloc_start() must be matched with
+ * media_pipeline_stop().
+ */
+__must_check int media_pipeline_alloc_start(struct media_entity *entity);
+
+/**
  * media_devnode_create() - creates and initializes a device node interface
  *
  * @mdev:	pointer to struct &media_device
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index 494685872254..643da0740ab0 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -608,6 +608,20 @@ void video_device_pipeline_stop(struct video_device *vdev);
 void __video_device_pipeline_stop(struct video_device *vdev);
 
 /**
+ * video_device_pipeline_alloc_start - Mark a pipeline as streaming
+ * @vdev: Starting video device
+ *
+ * video_device_pipeline_alloc_start() is similar to video_device_pipeline_start()
+ * but instead of working on a given pipeline the function will use an
+ * existing pipeline if the video device is already part of a pipeline, or
+ * allocate a new pipeline.
+ *
+ * Calls to video_device_pipeline_alloc_start() must be matched with
+ * video_device_pipeline_stop().
+ */
+__must_check int video_device_pipeline_alloc_start(struct video_device *vdev);
+
+/**
  * video_device_pipeline - Get the media pipeline a video device is part of
  * @vdev: The video device
  *