enum media_entity_type — Media entity type
enum media_entity_type {
MEDIA_ENTITY_TYPE_BASE,
MEDIA_ENTITY_TYPE_VIDEO_DEVICE,
MEDIA_ENTITY_TYPE_V4L2_SUBDEV
}; The entity isn't embedded in another subsystem structure.
The entity is embedded in a struct video_device instance.
The entity is embedded in a struct v4l2_subdev instance.
Media entity objects are often not instantiated directly, but the media entity structure is inherited by (through embedding) other subsystem-specific structures. The media entity type identifies the type of the subclass structure that implements a media entity instance.
This allows runtime type identification of media entities and safe casting to
the correct object type. For instance, a media entity structure instance
embedded in a v4l2_subdev structure instance will have the type
MEDIA_ENTITY_TYPE_V4L2_SUBDEV and can safely be cast to a v4l2_subdev
structure using the container_of macro.