Document how internal pads are used on source routes. Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> --- .../userspace-api/media/v4l/dev-subdev.rst | 20 +++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/userspace-api/media/v4l/dev-subdev.rst b/Documentation/userspace-api/media/v4l/dev-subdev.rst index a4f1df7093e8..5a46c9a9d352 100644 --- a/Documentation/userspace-api/media/v4l/dev-subdev.rst +++ b/Documentation/userspace-api/media/v4l/dev-subdev.rst @@ -551,6 +551,26 @@ A stream at a specific point in the media pipeline is identified by the sub-device and a (pad, stream) pair. For sub-devices that do not support multiplexed streams the 'stream' field is always 0. +.. _v4l2-subdev-source-routes: + +Source routes +^^^^^^^^^^^^^ + +Cases where a single sub-device pad is a source of multiple streams are special +as there is no external sink pad for such a route. In those cases, the sources +of the streams are indicated by source routes that have an internal source pad +as the sink pad of such a route. Internal source pads have the +:ref:`MEDIA_PAD_FL_INTERNAL <MEDIA-PAD-FL-INTERNAL>` and ``MEDIA_PAD_FL_SINK`` +pad flags set. + +Internal source pads have all the properties of a sink pad in such case, +including formats and selections. The format in this case is the source format +of the stream. An internal pad always has a single stream only (0). + +Generally source routes are not modifiable but they can be activated and +deactivated using the :ref:`V4L2_SUBDEV_ROUTE_FL_ACTIVE +<v4l2-subdev-routing-flags>` flag, depending on driver capabilities. + Interaction between routes, streams, formats and selections ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -- 2.39.2
