[media] v4l: Make v4l2_subdev inherit from media_entity

V4L2 subdevices are media entities. As such they need to inherit from
(include) the media_entity structure.

When registering/unregistering the subdevice, the media entity is
automatically registered/unregistered. The entity is acquired on device
open and released on device close.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 0f9937b..6f51ce4 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -21,6 +21,7 @@
 #ifndef _V4L2_SUBDEV_H
 #define _V4L2_SUBDEV_H
 
+#include <media/media-entity.h>
 #include <media/v4l2-common.h>
 #include <media/v4l2-dev.h>
 #include <media/v4l2-mediabus.h>
@@ -450,6 +451,9 @@
    stand-alone or embedded in a larger struct.
  */
 struct v4l2_subdev {
+#if defined(CONFIG_MEDIA_CONTROLLER)
+	struct media_entity entity;
+#endif
 	struct list_head list;
 	struct module *owner;
 	u32 flags;
@@ -472,6 +476,8 @@
 	unsigned int nevents;
 };
 
+#define media_entity_to_v4l2_subdev(ent) \
+	container_of(ent, struct v4l2_subdev, entity)
 #define vdev_to_v4l2_subdev(vdev) \
 	container_of(vdev, struct v4l2_subdev, devnode)