diff options
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/media/v4l2-subdev.rst | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/Documentation/driver-api/media/v4l2-subdev.rst b/Documentation/driver-api/media/v4l2-subdev.rst index 29e07e23f888..41ccb3e5c707 100644 --- a/Documentation/driver-api/media/v4l2-subdev.rst +++ b/Documentation/driver-api/media/v4l2-subdev.rst @@ -275,8 +275,13 @@ system the .unbind() method is called. All three callbacks are optional. V4L2 sub-device userspace API ----------------------------- -Beside exposing a kernel API through the :c:type:`v4l2_subdev_ops` structure, -V4L2 sub-devices can also be controlled directly by userspace applications. +Bridge drivers traditionally expose one or multiple video nodes to userspace, +and control subdevices through the :c:type:`v4l2_subdev_ops` operations in +response to video node operations. This hides the complexity of the underlying +hardware from applications. For complex devices, finer-grained control of the +device than what the video nodes offer may be required. In those cases, bridge +drivers that implement :ref:`the media controller API <media_controller>` may +opt for making the subdevice operations directly accessible from userpace. Device nodes named ``v4l-subdev``\ *X* can be created in ``/dev`` to access sub-devices directly. If a sub-device supports direct userspace configuration |