[libcamera-devel] [PATCH v2 5/6] media: entity: Add support for ancillary links

[Daniel Scally]

Add functions to create ancillary links, so that they don't need to
be manually created by users.

Signed-off-by: Daniel Scally <djrscally at gmail.com>
---

Changes since v1:

	- Hardcoded MEDIA_LINK_FL_IMMUTABLE and MEDIA_LINK_FL_ENABLED (Laurent)

Changes since the rfc:

	- (Laurent) Set gobj0 and gobj1 directly instead of the other union
	members
	- (Laurent) Added MEDIA_LNK_FL_IMMUTABLE to the kerneldoc for the new
	create function

 drivers/media/mc/mc-entity.c | 22 ++++++++++++++++++++++
 include/media/media-entity.h | 21 +++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
index 29d1285c805a..7bf2c73a3886 100644
--- a/drivers/media/mc/mc-entity.c
+++ b/drivers/media/mc/mc-entity.c
@@ -1050,3 +1050,25 @@ void media_remove_intf_links(struct media_interface *intf)
 	mutex_unlock(&mdev->graph_mutex);
 }
 EXPORT_SYMBOL_GPL(media_remove_intf_links);
+
+struct media_link *media_create_ancillary_link(struct media_entity *primary,
+					       struct media_entity *ancillary)
+{
+	struct media_link *link;
+
+	link = media_add_link(&primary->links);
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+
+	link->gobj0 = &primary->graph_obj;
+	link->gobj1 = &ancillary->graph_obj;
+	link->flags = MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED |
+		      MEDIA_LNK_FL_ANCILLARY_LINK;
+
+	/* Initialize graph object embedded in the new link */
+	media_gobj_create(primary->graph_obj.mdev, MEDIA_GRAPH_LINK,
+			  &link->graph_obj);
+
+	return link;
+}
+EXPORT_SYMBOL_GPL(media_create_ancillary_link);
diff --git a/include/media/media-entity.h b/include/media/media-entity.h
index fea489f03d57..afeda41ece4c 100644
--- a/include/media/media-entity.h
+++ b/include/media/media-entity.h
@@ -1104,6 +1104,27 @@ void media_remove_intf_links(struct media_interface *intf);
  * it will issue a call to @operation\(@entity, @args\).
  */
 
+/**
+ * media_create_ancillary_link() - create an ancillary link between two
+ *				   instances of &media_entity
+ *
+ * @primary:	pointer to the primary &media_entity
+ * @ancillary:	pointer to the ancillary &media_entity
+ *
+ * Create an ancillary link between two entities, indicating that they
+ * represent two connected pieces of hardware that form a single logical unit.
+ * A typical example is a camera lens being linked to the sensor that it is
+ * supporting.
+ *
+ * The function sets both MEDIA_LNK_FL_ENABLED and MEDIA_LNK_FL_IMMUTABLE for
+ * the new link. This behaviour may be subject to change in the future, so
+ * userspace applications using ancillary links should ensure that ancillary
+ * links are enabled when in use.
+ */
+struct media_link *
+media_create_ancillary_link(struct media_entity *primary,
+			    struct media_entity *ancillary);
+
 #define media_entity_call(entity, operation, args...)			\
 	(((entity)->ops && (entity)->ops->operation) ?			\
 	 (entity)->ops->operation((entity) , ##args) : -ENOIOCTLCMD)
-- 
2.25.1