linux-kernel - Re: [PATCH v3 1/4] media: mc-entity.c: add media_graph_walk_next

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Message-ID: <20200424134609.GD4040416@oden.dyn.berto.se>
Date:   Fri, 24 Apr 2020 15:46:09 +0200
From:   Niklas Söderlund 
        <niklas.soderlund@...natech.se>
To:     Helen Koike <helen.koike@...labora.com>
Cc:     linux-media@...r.kernel.org, kernel@...labora.com,
        linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        hans.verkuil@...co.com, skhan@...uxfoundation.org,
        mchehab@...nel.org
Subject: Re: [PATCH v3 1/4] media: mc-entity.c: add
 media_graph_walk_next_stream()

Hi Helen,

Thanks for your work.

On 2020-04-14 22:30:41 -0300, Helen Koike wrote:
> Add media_graph_walk_next_stream() function to follow links only from
> sink to source (not the opposite) to allow iteration only through the
> entities participating in a given stream.
> 
> This is useful to allow calling .s_stream() callback only in the
> subdevices that requires to be enabled/disabled, and avoid calling this
> callback when not required.
> 
> Signed-off-by: Helen Koike <helen.koike@...labora.com>
> 
> ---
> 
> Changes in v3:
> - Patch re-added in the series from version 1
> 
> Changes in v2: None
> 
>  drivers/media/mc/mc-entity.c | 34 +++++++++++++++++++++++++++++++---
>  include/media/media-entity.h | 15 +++++++++++++++
>  2 files changed, 46 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
> index 211279c5fd77d..0d44c2de23e6f 100644
> --- a/drivers/media/mc/mc-entity.c
> +++ b/drivers/media/mc/mc-entity.c
> @@ -228,6 +228,11 @@ EXPORT_SYMBOL_GPL(media_entity_pads_init);
>   * Graph traversal
>   */
>  
> +enum media_graph_walk_type {
> +	MEDIA_GRAPH_WALK_CONNECTED_NODES,
> +	MEDIA_GRAPH_WALK_STREAM_NODES,
> +};
> +
>  static struct media_entity *
>  media_entity_other(struct media_entity *entity, struct media_link *link)
>  {
> @@ -305,7 +310,8 @@ void media_graph_walk_start(struct media_graph *graph,
>  }
>  EXPORT_SYMBOL_GPL(media_graph_walk_start);
>  
> -static void media_graph_walk_iter(struct media_graph *graph)
> +static void media_graph_walk_iter(struct media_graph *graph,
> +				  enum media_graph_walk_type type)
>  {
>  	struct media_entity *entity = stack_top(graph);
>  	struct media_link *link;
> @@ -326,6 +332,15 @@ static void media_graph_walk_iter(struct media_graph *graph)
>  	/* Get the entity in the other end of the link . */
>  	next = media_entity_other(entity, link);
>  
> +	if (type == MEDIA_GRAPH_WALK_STREAM_NODES
> +	    && next == link->sink->entity) {
> +		link_top(graph) = link_top(graph)->next;
> +		dev_dbg(entity->graph_obj.mdev->dev,
> +			"walk: skipping '%s' (outside of the stream path)\n",
> +			link->sink->entity->name);
> +		return;
> +	}
> +
>  	/* Has the entity already been visited? */
>  	if (media_entity_enum_test_and_set(&graph->ent_enum, next)) {
>  		link_top(graph) = link_top(graph)->next;
> @@ -342,7 +357,9 @@ static void media_graph_walk_iter(struct media_graph *graph)
>  		next->name);
>  }
>  
> -struct media_entity *media_graph_walk_next(struct media_graph *graph)
> +static struct media_entity *
> +__media_graph_walk_next(struct media_graph *graph,
> +			enum media_graph_walk_type type)
>  {
>  	struct media_entity *entity;
>  
> @@ -355,7 +372,7 @@ struct media_entity *media_graph_walk_next(struct media_graph *graph)
>  	 * found.
>  	 */
>  	while (link_top(graph) != &stack_top(graph)->links)
> -		media_graph_walk_iter(graph);
> +		media_graph_walk_iter(graph, type);
>  
>  	entity = stack_pop(graph);
>  	dev_dbg(entity->graph_obj.mdev->dev,
> @@ -363,8 +380,19 @@ struct media_entity *media_graph_walk_next(struct media_graph *graph)
>  
>  	return entity;
>  }
> +
> +struct media_entity *media_graph_walk_next(struct media_graph *graph)
> +{
> +	return __media_graph_walk_next(graph, MEDIA_GRAPH_WALK_CONNECTED_NODES);
> +}
>  EXPORT_SYMBOL_GPL(media_graph_walk_next);
>  
> +struct media_entity *media_graph_walk_next_stream(struct media_graph *graph)
> +{
> +	return __media_graph_walk_next(graph,  MEDIA_GRAPH_WALK_STREAM_NODES);

One space to much after the ','. With this fixed,

Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@...natech.se>

> +}
> +EXPORT_SYMBOL_GPL(media_graph_walk_next_stream);
> +
>  int media_entity_get_fwnode_pad(struct media_entity *entity,
>  				struct fwnode_handle *fwnode,
>  				unsigned long direction_flags)
> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> index 8cb2c504a05c7..f17a5180ce524 100644
> --- a/include/media/media-entity.h
> +++ b/include/media/media-entity.h
> @@ -927,6 +927,21 @@ void media_graph_walk_start(struct media_graph *graph,
>   */
>  struct media_entity *media_graph_walk_next(struct media_graph *graph);
>  
> +/**
> + * media_graph_walk_next_stream - Get the next entity in the graph
> + * @graph: Media graph structure
> + *
> + * Perform a depth-first traversal of the given media entities graph only
> + * following links from sink to source (and not the opposite).
> + *
> + * The graph structure must have been previously initialized with a call to
> + * media_graph_walk_start().
> + *
> + * Return: returns the next entity in the graph in the stream path
> + * or %NULL if the whole stream path have been traversed.
> + */
> +struct media_entity *media_graph_walk_next_stream(struct media_graph *graph);
> +
>  /**
>   * media_pipeline_start - Mark a pipeline as streaming
>   * @entity: Starting entity
> -- 
> 2.26.0
> 

-- 
Regards,
Niklas Söderlund