Hi Sakari On Fri, Jun 30, 2023 at 11:43:35PM +0300, Sakari Ailus wrote: > 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 > +^^^^^^^^^^^^^ I always found the concept of source routes a bit confusing, should we instead just present internal pads ? > + > +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. All this last part is a little bit hard to parse, not your fault but the fact "internal source pads" are actually "SINK" pads is a bit confusing ? Can we remove the "source route" concept to avoid mixing source/sink ? This can be rewritten as Internal pads ^^^^^^^^^^^^^ 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. A typical example is a sensor device which produces a video stream and a metadata stream of embedded data. To support such cases internal pads are introduced as sink pads of such internally generated streams. 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, Also here, "Internal source pads" are actually sinks :) I would drop "source" from "Internal source pads" > +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 s/source routes/internal routes/ ? > +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 >
