Re: [PATCH v2 14/22] media: Keep using the same graph walk object for a given pipeline

[Mauro Carvalho Chehab <mchehab@osg.samsung.com>]

Em Sun, 29 Nov 2015 21:20:15 +0200
Sakari Ailus <sakari.ailus@iki.fi> escreveu:

> Initialise a given graph walk object once, and then keep using it whilst
> the same pipeline is running. Once the pipeline is stopped, release the
> graph walk object.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/media/media-entity.c | 17 +++++++++++------
>  include/media/media-entity.h |  4 +++-
>  2 files changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
> index 7429c03..137aa09d 100644
> --- a/drivers/media/media-entity.c
> +++ b/drivers/media/media-entity.c
> @@ -488,10 +488,10 @@ __must_check int media_entity_pipeline_start(struct media_entity *entity,
>  
>  	mutex_lock(&mdev->graph_mutex);
>  
> -	ret = media_entity_graph_walk_init(&pipe->graph, mdev);
> -	if (ret) {
> -		mutex_unlock(&mdev->graph_mutex);
> -		return ret;
> +	if (!pipe->streaming_count++) {
> +		ret = media_entity_graph_walk_init(&pipe->graph, mdev);
> +		if (ret)
> +			goto error_graph_walk_start;
>  	}
>  
>  	media_entity_graph_walk_start(&pipe->graph, entity);
> @@ -592,7 +592,9 @@ error:
>  			break;
>  	}
>  
> -	media_entity_graph_walk_cleanup(graph);
> +error_graph_walk_start:
> +	if (!--pipe->streaming_count)
> +		media_entity_graph_walk_cleanup(graph);
>  
>  	mutex_unlock(&mdev->graph_mutex);
>  
> @@ -616,9 +618,11 @@ void media_entity_pipeline_stop(struct media_entity *entity)
>  {
>  	struct media_device *mdev = entity->graph_obj.mdev;
>  	struct media_entity_graph *graph = &entity->pipe->graph;
> +	struct media_pipeline *pipe = entity->pipe;
>  
>  	mutex_lock(&mdev->graph_mutex);
>  
> +	BUG_ON(!pipe->streaming_count);

Cant it be replaced by a WARN_ON()?

>  	media_entity_graph_walk_start(graph, entity);
>  
>  	while ((entity = media_entity_graph_walk_next(graph))) {
> @@ -627,7 +631,8 @@ void media_entity_pipeline_stop(struct media_entity *entity)
>  			entity->pipe = NULL;
>  	}
>  
> -	media_entity_graph_walk_cleanup(graph);
> +	if (!--pipe->streaming_count)
> +		media_entity_graph_walk_cleanup(graph);
>  
>  	mutex_unlock(&mdev->graph_mutex);
>  }
> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> index 8122736..85c2656 100644
> --- a/include/media/media-entity.h
> +++ b/include/media/media-entity.h
> @@ -116,9 +116,11 @@ struct media_entity_graph {
>  /*
>   * struct media_pipeline - Media pipeline related information
>   *
> - * @graph:	Media graph walk during pipeline start / stop
> + * @streaming_count:	Streaming start count - streaming stop count
> + * @graph:		Media graph walk during pipeline start / stop
>   */
>  struct media_pipeline {
> +	int streaming_count;
>  	struct media_entity_graph graph;
>  };
>