Hi Sakari, Thank you for the patch. On Wed, Apr 24, 2024 at 03:22:32PM +0300, Sakari Ailus wrote: > Document S_ROUTING behaviour for different devices. > > Generally in devices that produce streams the streams are static and some > can be enabled and disabled, whereas in devices that just transport them > or write them to memory, more configurability is allowed. Document this. > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > Reviewed-by: Julien Massot <julien.massot@xxxxxxxxxxxxx> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > --- > .../userspace-api/media/v4l/dev-subdev.rst | 23 +++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/Documentation/userspace-api/media/v4l/dev-subdev.rst b/Documentation/userspace-api/media/v4l/dev-subdev.rst > index b76e02e54512..0f9eda3187f3 100644 > --- a/Documentation/userspace-api/media/v4l/dev-subdev.rst > +++ b/Documentation/userspace-api/media/v4l/dev-subdev.rst > @@ -572,6 +572,29 @@ Any configurations of a stream within a pad, such as format or selections, > are independent of similar configurations on other streams. This is > subject to change in the future. > > +Device types and routing setup > +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > + > +Different kinds of sub-devices have differing behaviour for route activation, > +depending on the hardware. In all cases, however, only routes that have the > +``V4L2_SUBDEV_STREAM_FL_ACTIVE`` flag set are active. > + > +Devices generating the streams may allow enabling and disabling some of the > +routes or have a fixed routing configuration. If the routes can be disabled, not > +declaring the routes (or declaring them without > +``VIDIOC_SUBDEV_STREAM_FL_ACTIVE`` flag set) in ``VIDIOC_SUBDEV_S_ROUTING`` will > +disable the routes. ``VIDIOC_SUBDEV_S_ROUTING`` will still return such routes > +back to the user in the routes array, with the ``V4L2_SUBDEV_STREAM_FL_ACTIVE`` > +flag unset. > + > +Devices transporting the streams almost always have more configurability with > +respect to routing. Typically any route between the sub-device's sink and source > +pads is possible, and multiple routes (usually up to certain limited number) may > +be active simultaneously. For such devices, no routes are created by the driver > +and user-created routes are fully replaced when ``VIDIOC_SUBDEV_S_ROUTING`` is > +called on the sub-device. Such newly created routes have the device's default > +configuration for format and selection rectangles. > + > Configuring streams > ^^^^^^^^^^^^^^^^^^^ > -- Regards, Laurent Pinchart
