[PATCH v2 04/55] media: mc-entity: Add a new helper function to get a remote pad for a pad

[Hans Verkuil]

On 7/1/22 01:06, Laurent Pinchart wrote:
> The newly added media_entity_remote_source_pad() helper function handles

Same here: this should be media_entity_remote_source_pad_unique().

> use cases where the entity has a link enabled uniqueness constraint
> covering all pads. There are use cases where the constraint covers a
> specific pad only. Add a new media_pad_remote_pad_unique() function to
> handle this. It operates as media_entity_remote_source_pad(), but on a

Ditto.

The commit message of this and the previous patch must be updated, either
in a new v3 or separate v2.1 follow-up patches for these two, or before
making a PR. It's very confusing to mix old and new names :-)

Regards,

	Hans

> given pad instead of on the entity.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Acked-by: Hans Verkuil <hverkuil-cisco at xs4all.nl>
> ---
> Changes since v1:
> 
> - Rename media_pad_remote_pad() to media_pad_remote_pad_unique()
> ---
>  Documentation/driver-api/media/mc-core.rst |  5 ++--
>  drivers/media/mc/mc-entity.c               | 31 ++++++++++++++++++++++
>  include/media/media-entity.h               | 18 +++++++++++++
>  3 files changed, 52 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/driver-api/media/mc-core.rst b/Documentation/driver-api/media/mc-core.rst
> index 66801506b2dd..644911936ad9 100644
> --- a/Documentation/driver-api/media/mc-core.rst
> +++ b/Documentation/driver-api/media/mc-core.rst
> @@ -186,8 +186,9 @@ is required and the graph structure can be freed normally.
>  
>  Helper functions can be used to find a link between two given pads, or a pad
>  connected to another pad through an enabled link
> -(:c:func:`media_entity_find_link()`, :c:func:`media_pad_remote_pad_first()` and
> -:c:func:`media_entity_remote_source_pad_unique()`).
> +(:c:func:`media_entity_find_link()`, :c:func:`media_pad_remote_pad_first()`n
> +:c:func:`media_entity_remote_source_pad_unique()` and
> +:c:func:`media_pad_remote_pad_unique()`).
>  
>  Use count and power handling
>  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
> index bd7145932137..7082403d5800 100644
> --- a/drivers/media/mc/mc-entity.c
> +++ b/drivers/media/mc/mc-entity.c
> @@ -960,6 +960,37 @@ media_entity_remote_pad_unique(const struct media_entity *entity,
>  }
>  EXPORT_SYMBOL_GPL(media_entity_remote_pad_unique);
>  
> +struct media_pad *media_pad_remote_pad_unique(const struct media_pad *pad)
> +{
> +	struct media_pad *found_pad = NULL;
> +	struct media_link *link;
> +
> +	list_for_each_entry(link, &pad->entity->links, list) {
> +		struct media_pad *remote_pad;
> +
> +		if (!(link->flags & MEDIA_LNK_FL_ENABLED))
> +			continue;
> +
> +		if (link->sink == pad)
> +			remote_pad = link->source;
> +		else if (link->source == pad)
> +			remote_pad = link->sink;
> +		else
> +			continue;
> +
> +		if (found_pad)
> +			return ERR_PTR(-ENOTUNIQ);
> +
> +		found_pad = remote_pad;
> +	}
> +
> +	if (!found_pad)
> +		return ERR_PTR(-ENOLINK);
> +
> +	return found_pad;
> +}
> +EXPORT_SYMBOL_GPL(media_pad_remote_pad_unique);
> +
>  static void media_interface_init(struct media_device *mdev,
>  				 struct media_interface *intf,
>  				 u32 gobj_type,
> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> index aecd1691b297..cd0690cff4c2 100644
> --- a/include/media/media-entity.h
> +++ b/include/media/media-entity.h
> @@ -859,6 +859,24 @@ struct media_link *media_entity_find_link(struct media_pad *source,
>   */
>  struct media_pad *media_pad_remote_pad_first(const struct media_pad *pad);
>  
> +/**
> + * media_pad_remote_pad_unique - Find a remote pad connected to a pad
> + * @pad: The pad
> + *
> + * Search for and return a remote pad connected to @pad through an enabled
> + * link. If multiple (or no) remote pads are found, an error is returned.
> + *
> + * The uniqueness constraint makes this helper function suitable for entities
> + * that support a single active source at a time on a given pad.
> + *
> + * Return: A pointer to the remote pad, or one of the following error pointers
> + * if an error occurs:
> + *
> + * * -ENOTUNIQ - Multiple links are enabled
> + * * -ENOLINK - No connected pad found
> + */
> +struct media_pad *media_pad_remote_pad_unique(const struct media_pad *pad);
> +
>  /**
>   * media_entity_remote_pad_unique - Find a remote pad connected to an entity
>   * @entity: The entity