Commit 5680fe45 authored by Laurent Pinchart's avatar Laurent Pinchart Committed by Mauro Carvalho Chehab
Browse files

media: mc-entity: Add a new helper function to get a remote pad 



The media_entity_remote_pad_first() helper function returns the first
remote pad it finds connected to a given pad. Beside being possibly
non-deterministic (as it stops at the first enabled link), the fact that
it returns the first match makes it unsuitable for drivers that need to
guarantee that a single link is enabled, for instance when an entity can
process data from one of multiple sources at a time.

For those use cases, add a new helper function,
media_entity_remote_pad_unique(), that operates on an entity and returns
a remote pad, with a guarantee that only one link is enabled. To ease
its use in drivers, also add an inline wrapper that locates source pads
specifically. A wrapper that locates sink pads can easily be added when
needed.

Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@kernel.org>
parent b2e44430

Documentation/driver-api/media/mc-core.rst

+2 −1
Original line number Diff line number Diff line
@@ -186,7 +186,8 @@ 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()` and :c:func:`media_pad_remote_pad_first()`.

(:c:func:`media_entity_find_link()`, :c:func:`media_pad_remote_pad_first()` and

:c:func:`media_entity_remote_source_pad_unique()`).



Use count and power handling

^^^^^^^^^^^^^^^^^^^^^^^^^^^^

drivers/media/mc/mc-entity.c

+39 −0
Original line number Diff line number Diff line
@@ -921,6 +921,45 @@ struct media_pad *media_pad_remote_pad_first(const struct media_pad *pad) 
}

EXPORT_SYMBOL_GPL(media_pad_remote_pad_first);



struct media_pad *

media_entity_remote_pad_unique(const struct media_entity *entity,

			       unsigned int type)

{

	struct media_pad *pad = NULL;

	struct media_link *link;



	list_for_each_entry(link, &entity->links, list) {

		struct media_pad *local_pad;

		struct media_pad *remote_pad;



		if (((link->flags & MEDIA_LNK_FL_LINK_TYPE) !=

		     MEDIA_LNK_FL_DATA_LINK) ||

		    !(link->flags & MEDIA_LNK_FL_ENABLED))

			continue;



		if (type == MEDIA_PAD_FL_SOURCE) {

			local_pad = link->sink;

			remote_pad = link->source;

		} else {

			local_pad = link->source;

			remote_pad = link->sink;

		}



		if (local_pad->entity == entity) {

			if (pad)

				return ERR_PTR(-ENOTUNIQ);



			pad = remote_pad;

		}

	}



	if (!pad)

		return ERR_PTR(-ENOLINK);



	return pad;

}

EXPORT_SYMBOL_GPL(media_entity_remote_pad_unique);



static void media_interface_init(struct media_device *mdev,

				 struct media_interface *intf,

				 u32 gobj_type,

include/media/media-entity.h

+46 −0
Original line number Diff line number Diff line
@@ -859,6 +859,52 @@ 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_entity_remote_pad_unique - Find a remote pad connected to an entity

 * @entity: The entity

 * @type: The type of pad to find (MEDIA_PAD_FL_SINK or MEDIA_PAD_FL_SOURCE)

 *

 * Search for and return a remote pad of @type connected to @entity through an

 * enabled link. If multiple (or no) remote pads match these criteria, an error

 * is returned.

 *

 * The uniqueness constraint makes this helper function suitable for entities

 * that support a single active source or sink at a time.

 *

 * 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_entity_remote_pad_unique(const struct media_entity *entity,

			       unsigned int type);



/**

 * media_entity_remote_source_pad_unique - Find a remote source pad connected to

 *	an entity

 * @entity: The entity

 *

 * Search for and return a remote source pad connected to @entity through an

 * enabled link. If multiple (or no) remote pads match these criteria, an error

 * is returned.

 *

 * The uniqueness constraint makes this helper function suitable for entities

 * that support a single active source at a time.

 *

 * 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

 */

static inline struct media_pad *

media_entity_remote_source_pad_unique(const struct media_entity *entity)

{

	return media_entity_remote_pad_unique(entity, MEDIA_PAD_FL_SOURCE);

}



/**

 * media_entity_is_streaming - Test if an entity is part of a streaming pipeline

 * @entity: The entity