Hi Sakari, Thank you for the patch. On Tue, Apr 16, 2024 at 10:32:43PM +0300, Sakari Ailus wrote: > Document internal sink pads, pads that have both SINK and INTERNAL flags > set. Use the IMX219 camera sensor as an example. > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > Reviewed-by Julien Massot <julien.massot@xxxxxxxxxxxxx> > --- > .../userspace-api/media/v4l/dev-subdev.rst | 145 ++++++++++++++++++ > 1 file changed, 145 insertions(+) > > diff --git a/Documentation/userspace-api/media/v4l/dev-subdev.rst b/Documentation/userspace-api/media/v4l/dev-subdev.rst > index b76e02e54512..d30dcb9e2537 100644 > --- a/Documentation/userspace-api/media/v4l/dev-subdev.rst > +++ b/Documentation/userspace-api/media/v4l/dev-subdev.rst > @@ -553,6 +553,27 @@ 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-internal-source-pads: > + > +Internal sink pads and routing > +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > + > +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 represented by internal sink pads, which > +are sink pads that have the :ref:`MEDIA_PAD_FL_INTERNAL <MEDIA-PAD-FL-INTERNAL>` > +pad flag set. > + > +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). > + > +Routes from an internal sink pad to an external source pad are typically 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 > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > @@ -668,3 +689,127 @@ To configure this pipeline, the userspace must take the following steps: > the configurations along the stream towards the receiver, using > :ref:`VIDIOC_SUBDEV_S_FMT <VIDIOC_SUBDEV_G_FMT>` ioctls to configure each > stream endpoint in each sub-device. > + > +Internal pads setup example > +^^^^^^^^^^^^^^^^^^^^^^^^^^^ > + > +A simple example of a multiplexed stream setup might be as follows: > + > +- An IMX219 camera sensor source sub-device, with one source pad (0), one > + internal sink pad (1) as the source of the image data and an internal sink > + pad (2) as the source of the embedded data. There are two routes, one from the > + internal sink pad 1 to the source 0 (image data) and another from the internal s/source 0/source pad 0/ > + sink pad 2 to the source pad 0 (embedded data). Both streams are always > + active, i.e. there is no need to separately enable the embedded data > + stream. The sensor uses the CSI-2 interface. > + > +- A CSI-2 receiver in the SoC. The receiver has a single sink pad (pad 0), > + connected to the sensor, and two source pads (pads 1 and 2), to the DMA > + engine. The receiver demultiplexes the incoming streams to the source pads. s/engine/engines/ maybe better, "to two DMA engines". > + > +- DMA engines in the SoC, one for each stream. Each DMA engine is connected to a > + single source pad of the receiver. > + > +The sensor and the receiver are modelled as V4L2 sub-devices, exposed to > +userspace via /dev/v4l-subdevX device nodes. The DMA engines are modelled as > +V4L2 devices, exposed to userspace via /dev/videoX nodes. > + > +To configure this pipeline, the userspace must take the following steps: > + > +1) Set up media links between entities: enable the links from the sensor to the > + receiver and from the receiver to the DMA engines. This step does not differ > + from normal non-multiplexed media controller setup. > + > +2) Configure routing > + > +.. flat-table:: Camera sensor. There are no configurable routes. > + :header-rows: 1 > + > + * - Sink Pad/Stream > + - Source Pad/Stream > + - Routing Flags > + - Comments > + * - 1/0 > + - 0/0 > + - V4L2_SUBDEV_ROUTE_FL_ACTIVE > + - Pixel data stream from the sink pad "from the internal image sink pad" > + * - 2/0 > + - 0/1 > + - V4L2_SUBDEV_ROUTE_FL_ACTIVE > + - Metadata stream from the internal sink pad "internal embedded data sink pad" > + > +.. flat-table:: Receiver routing table. Typically both routes need to be > + explicitly set. > + :header-rows: 1 > + > + * - Sink Pad/Stream > + - Source Pad/Stream > + - Routing Flags > + - Comments > + * - 0/0 > + - 1/0 > + - V4L2_SUBDEV_ROUTE_FL_ACTIVE > + - Pixel data stream from camera sensor > + * - 0/1 > + - 2/0 > + - V4L2_SUBDEV_ROUTE_FL_ACTIVE > + - Metadata stream from camera sensor > + > +The options available in sensor's routing configuration are dictated by hardware s/in sensor/in the sensor/ > +capabilities: typically camera sensors always produce an image data stream while > +it may be possible to enable and disable the embedded data stream. Should this go after the first table ? > + > +3) Configure formats and selections > + > + This example assumes that the formats are propagated from sink pad to the > + source pad as-is. The tables contain fields of both struct v4l2_subdev_format > + and struct v4l2_mbus_framefmt. > + > +.. flat-table:: Formats set on the sub-devices. Bold values are set, others are > + static or propagated. The order is aligned with configured > + routes. > + :header-rows: 1 > + :fill-cells: > + > + * - Sub-device > + - Pad/Stream > + - Width > + - Height > + - Code > + * - :rspan:`3` IMX219 > + - 1/0 > + - 3296 > + - 2480 > + - MEDIA_BUS_FMT_SRGGB10 > + * - 0/0 > + - **3296** > + - **2480** > + - **MEDIA_BUS_FMT_SRGGB10** > + * - 2/0 > + - 3296 > + - 2 > + - MEDIA_BUS_FMT_IMX219_EMBEDDED We need a patch in this series to define this format. > + * - 1/1 I think this should be 0/1. > + - 3296 > + - 2 > + - MEDIA_BUS_FMT_META_10 > + * - :rspan:`3` CSI-2 receiver > + - 0/0 > + - **3296** > + - **2480** > + - **MEDIA_BUS_FMT_SRGGB10** > + * - 1/0 > + - 3296 > + - 2480 > + - MEDIA_BUS_FMT_SRGGB10 > + * - 0/1 > + - **3296** > + - **2** > + - **MEDIA_BUS_FMT_META_10** > + * - 2/0 > + - 3296 > + - 2 > + - MEDIA_BUS_FMT_META_10 > + > +The embedded data format does not need to be configured as the format is Do you mean the "format on the sensor's pads" ? It's a bit confusing if you don't specify it. > +dictated by the pixel data format in this case. -- Regards, Laurent Pinchart
