Hi Jacopo, On Mon, Jul 03, 2023 at 09:47:37AM +0200, Jacopo Mondi wrote: > 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" How about this (compared to the patch): diff --git a/Documentation/userspace-api/media/v4l/dev-subdev.rst b/Documentation/userspace-api/media/v4l/dev-subdev.rst index 5a46c9a9d352..9d544a29e78a 100644 --- a/Documentation/userspace-api/media/v4l/dev-subdev.rst +++ b/Documentation/userspace-api/media/v4l/dev-subdev.rst @@ -553,21 +553,23 @@ 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 +Internal pads and source routes +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Cases where a single sub-device source pad is traversed by multiple streams one +or more of which originate from within the sub-device itself are special as +there is no external sink pad for such routes. In those cases, the sources of +the internally generated streams are indicated by internal pads, pads which have +a :ref:`MEDIA_PAD_FL_INTERNAL` <MEDIA-PAD-FL-INTERNAL> pad flag set on the sink +pad of the route. A typical use case for these is a camera sensor device which +produces a pixel data stream and an embedded data stream. + +Internal pads have all the properties of an external pad, 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). + +/Source routes/ are routes from an internal sink pad to a(n external) source +pad. 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. I'll also check the ACTIVE route flag, it wasn't merged with the rest of the Tomi's streams series. -- Kind regards, Sakari Ailus
