Hi Dan,
Thank you for the patch.
On Tue, Jul 09, 2024 at 02:28:49PM +0100, Daniel Scally wrote:
> Record the number of video devices in a pipeline so that we can track
> in a central location how many need to be started before drivers must
> actually begin streaming.
>
> Signed-off-by: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx>
> ---
> Changes in v6:
>
> - New patch. This is intended to support Sakari's requirement for the
> driver not to start streaming before all of the video devices have
> called streamon(). This was the cleanest way I could think to acheive
> the goal, and lets us just check for start_count == required_count
> before streaming.
This violates the abstraction layers a bit, the MC code isn't supposed
to handle video devices like that.
What you can instead do is to use media_pipeline_for_each_entity() in
your driver when starting the pipeline to iterate over all entities, and
count the video devices there.
>
> drivers/media/mc/mc-entity.c | 5 +++++
> include/media/media-entity.h | 2 ++
> 2 files changed, 7 insertions(+)
>
> diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
> index 96dd0f6ccd0d..1e8186b13b55 100644
> --- a/drivers/media/mc/mc-entity.c
> +++ b/drivers/media/mc/mc-entity.c
> @@ -596,6 +596,9 @@ static int media_pipeline_add_pad(struct media_pipeline *pipe,
>
> list_add_tail(&ppad->list, &pipe->pads);
>
> + if (pad->entity->obj_type == MEDIA_ENTITY_TYPE_VIDEO_DEVICE)
> + pipe->required_count++;
> +
> dev_dbg(pad->graph_obj.mdev->dev,
> "media pipeline: added pad '%s':%u\n",
> pad->entity->name, pad->index);
> @@ -713,6 +716,8 @@ static void media_pipeline_cleanup(struct media_pipeline *pipe)
> list_del(&ppad->list);
> kfree(ppad);
> }
> +
> + pipe->required_count = 0;
> }
>
> static int media_pipeline_populate(struct media_pipeline *pipe,
> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> index 0393b23129eb..ab84458b40dc 100644
> --- a/include/media/media-entity.h
> +++ b/include/media/media-entity.h
> @@ -104,12 +104,14 @@ struct media_graph {
> * @mdev: The media device the pipeline is part of
> * @pads: List of media_pipeline_pad
> * @start_count: Media pipeline start - stop count
> + * @required_count: Number of starts required to be "running"
> */
> struct media_pipeline {
> bool allocated;
> struct media_device *mdev;
> struct list_head pads;
> int start_count;
> + int required_count;
> };
>
> /**
--
Regards,
Laurent Pinchart
