Re: [PATCH v2 02/30] media: entity: Use pads instead of entities in the media graph walk stack

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Niklas,

Thank you for the patch.

On Fri, Nov 02, 2018 at 12:31:16AM +0100, Niklas Söderlund wrote:
> From: Sakari Ailus <sakari.ailus@linux.intel.com>
> 
> Change the media graph walk stack structure to use media pads instead of
> using media entities. In addition to the entity, the pad contains the
> information which pad in the entity are being dealt with.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> ---
>  drivers/media/media-entity.c | 53 ++++++++++++++++++------------------
>  include/media/media-entity.h |  6 ++--
>  2 files changed, 29 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/media/media-entity.c b/drivers/media/media-entity.c
> index 2bbc07de71aa5e6d..892e64a0a9d8ec42 100644
> --- a/drivers/media/media-entity.c
> +++ b/drivers/media/media-entity.c
> @@ -237,40 +237,39 @@ EXPORT_SYMBOL_GPL(media_entity_pads_init);
>   * Graph traversal
>   */
>  
> -static struct media_entity *
> -media_entity_other(struct media_entity *entity, struct media_link *link)
> +static struct media_pad *
> +media_entity_other(struct media_pad *pad, struct media_link *link)
>  {
> -	if (link->source->entity == entity)
> -		return link->sink->entity;
> +	if (link->source == pad)
> +		return link->sink;
>  	else
> -		return link->source->entity;
> +		return link->source;
>  }
>  
>  /* push an entity to traversal stack */
> -static void stack_push(struct media_graph *graph,
> -		       struct media_entity *entity)
> +static void stack_push(struct media_graph *graph, struct media_pad *pad)
>  {
>  	if (graph->top == MEDIA_ENTITY_ENUM_MAX_DEPTH - 1) {
>  		WARN_ON(1);
>  		return;
>  	}
>  	graph->top++;
> -	graph->stack[graph->top].link = entity->links.next;
> -	graph->stack[graph->top].entity = entity;
> +	graph->stack[graph->top].link = pad->entity->links.next;
> +	graph->stack[graph->top].pad = pad;
>  }
>  
> -static struct media_entity *stack_pop(struct media_graph *graph)
> +static struct media_pad *stack_pop(struct media_graph *graph)
>  {
> -	struct media_entity *entity;
> +	struct media_pad *pad;
>  
> -	entity = graph->stack[graph->top].entity;
> +	pad = graph->stack[graph->top].pad;
>  	graph->top--;
>  
> -	return entity;
> +	return pad;
>  }
>  
>  #define link_top(en)	((en)->stack[(en)->top].link)
> -#define stack_top(en)	((en)->stack[(en)->top].entity)
> +#define stack_top(en)	((en)->stack[(en)->top].pad)
>  
>  /**
>   * media_graph_walk_init - Allocate resources for graph walk
> @@ -306,8 +305,8 @@ void media_graph_walk_start(struct media_graph *graph, struct media_pad *pad)
>  	media_entity_enum_set(&graph->ent_enum, pad->entity);
>  
>  	graph->top = 0;
> -	graph->stack[graph->top].entity = NULL;
> -	stack_push(graph, pad->entity);
> +	graph->stack[graph->top].pad = NULL;
> +	stack_push(graph, pad);
>  	dev_dbg(pad->graph_obj.mdev->dev,
>  		"begin graph walk at '%s':%u\n", pad->entity->name, pad->index);
>  }
> @@ -315,16 +314,16 @@ EXPORT_SYMBOL_GPL(media_graph_walk_start);
>  
>  static void media_graph_walk_iter(struct media_graph *graph)
>  {
> -	struct media_entity *entity = stack_top(graph);
> +	struct media_pad *pad = stack_top(graph);
>  	struct media_link *link;
> -	struct media_entity *next;
> +	struct media_pad *next;
>  
>  	link = list_entry(link_top(graph), typeof(*link), list);
>  
>  	/* The link is not enabled so we do not follow. */
>  	if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
>  		link_top(graph) = link_top(graph)->next;
> -		dev_dbg(entity->graph_obj.mdev->dev,
> +		dev_dbg(pad->graph_obj.mdev->dev,
>  			"walk: skipping disabled link '%s':%u -> '%s':%u\n",
>  			link->source->entity->name, link->source->index,
>  			link->sink->entity->name, link->sink->index);
> @@ -332,22 +331,22 @@ static void media_graph_walk_iter(struct media_graph *graph)
>  	}
>  
>  	/* Get the entity in the other end of the link . */

s/entity/pad/

> -	next = media_entity_other(entity, link);
> +	next = media_entity_other(pad, link);
>  
>  	/* Has the entity already been visited? */

s/entity/pad's entity/

> -	if (media_entity_enum_test_and_set(&graph->ent_enum, next)) {
> +	if (media_entity_enum_test_and_set(&graph->ent_enum, next->entity)) {
>  		link_top(graph) = link_top(graph)->next;
> -		dev_dbg(entity->graph_obj.mdev->dev,
> +		dev_dbg(pad->graph_obj.mdev->dev,
>  			"walk: skipping entity '%s' (already seen)\n",
> -			next->name);
> +			next->entity->name);
>  		return;
>  	}
>  
>  	/* Push the new entity to stack and start over. */

s/entity/pad/

>  	link_top(graph) = link_top(graph)->next;
>  	stack_push(graph, next);
> -	dev_dbg(entity->graph_obj.mdev->dev, "walk: pushing '%s' on stack\n",
> -		next->name);
> +	dev_dbg(next->graph_obj.mdev->dev, "walk: pushing '%s':%u on stack\n",
> +		next->entity->name, next->index);
>  }
>  
>  struct media_entity *media_graph_walk_next(struct media_graph *graph)
> @@ -362,10 +361,10 @@ struct media_entity *media_graph_walk_next(struct media_graph *graph)
>  	 * top of the stack until no more entities on the level can be
>  	 * found.
>  	 */
> -	while (link_top(graph) != &stack_top(graph)->links)
> +	while (link_top(graph) != &stack_top(graph)->entity->links)
>  		media_graph_walk_iter(graph);
>  
> -	entity = stack_pop(graph);
> +	entity = stack_pop(graph)->entity;
>  	dev_dbg(entity->graph_obj.mdev->dev,
>  		"walk: returning entity '%s'\n", entity->name);
>  
> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> index 07ab141e739ef5ff..99c7606f01317741 100644
> --- a/include/media/media-entity.h
> +++ b/include/media/media-entity.h
> @@ -86,16 +86,16 @@ struct media_entity_enum {
>   * struct media_graph - Media graph traversal state
>   *
>   * @stack:		Graph traversal stack; the stack contains information
> - *			on the path the media entities to be walked and the
> + *			on the path the media pads to be walked and the

This sentence doesn't make too much sense to me, are we missing
something ?

The rest looks OK to me, so with this fixed,

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

>   *			links through which they were reached.
> - * @stack.entity:	pointer to &struct media_entity at the graph.
> + * @stack.pad:		pointer to &struct media_pad at the graph.
>   * @stack.link:		pointer to &struct list_head.
>   * @ent_enum:		Visited entities
>   * @top:		The top of the stack
>   */
>  struct media_graph {
>  	struct {
> -		struct media_entity *entity;
> +		struct media_pad *pad;
>  		struct list_head *link;
>  	} stack[MEDIA_ENTITY_ENUM_MAX_DEPTH];
>  

-- 
Regards,

Laurent Pinchart