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>

1 files changed, 14 insertions, 0 deletions

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
  *