diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/video4linux/v4l2-framework.txt | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt index 062708169def..77d96f4e3f50 100644 --- a/Documentation/video4linux/v4l2-framework.txt +++ b/Documentation/video4linux/v4l2-framework.txt @@ -268,6 +268,26 @@ A sub-device driver initializes the v4l2_subdev struct using: Afterwards you need to initialize subdev->name with a unique name and set the module owner. This is done for you if you use the i2c helper functions. +If integration with the media framework is needed, you must initialize the +media_entity struct embedded in the v4l2_subdev struct (entity field) by +calling media_entity_init(): + + struct media_pad *pads = &my_sd->pads; + int err; + + err = media_entity_init(&sd->entity, npads, pads, 0); + +The pads array must have been previously initialized. There is no need to +manually set the struct media_entity type and name fields, but the revision +field must be initialized if needed. + +A reference to the entity will be automatically acquired/released when the +subdev device node (if any) is opened/closed. + +Don't forget to cleanup the media entity before the sub-device is destroyed: + + media_entity_cleanup(&sd->entity); + A device (bridge) driver needs to register the v4l2_subdev with the v4l2_device: @@ -277,6 +297,9 @@ This can fail if the subdev module disappeared before it could be registered. After this function was called successfully the subdev->dev field points to the v4l2_device. +If the v4l2_device parent device has a non-NULL mdev field, the sub-device +entity will be automatically registered with the media device. + You can unregister a sub-device using: v4l2_device_unregister_subdev(sd); |