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: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
index 66ba062..767846b 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -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,
