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diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-routing.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-routing.rst new file mode 100644 index 0000000000..72677a280c --- /dev/null +++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-routing.rst @@ -0,0 +1,148 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later +.. c:namespace:: V4L + +.. _VIDIOC_SUBDEV_G_ROUTING: + +****************************************************** +ioctl VIDIOC_SUBDEV_G_ROUTING, VIDIOC_SUBDEV_S_ROUTING +****************************************************** + +Name +==== + +VIDIOC_SUBDEV_G_ROUTING - VIDIOC_SUBDEV_S_ROUTING - Get or set routing between streams of media pads in a media entity. + + +Synopsis +======== + +.. c:macro:: VIDIOC_SUBDEV_G_ROUTING + +``int ioctl(int fd, VIDIOC_SUBDEV_G_ROUTING, struct v4l2_subdev_routing *argp)`` + +.. c:macro:: VIDIOC_SUBDEV_S_ROUTING + +``int ioctl(int fd, VIDIOC_SUBDEV_S_ROUTING, struct v4l2_subdev_routing *argp)`` + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`open() <func-open>`. + +``argp`` + Pointer to struct :c:type:`v4l2_subdev_routing`. + + +Description +=========== + +These ioctls are used to get and set the routing in a media entity. +The routing configuration determines the flows of data inside an entity. + +Drivers report their current routing tables using the +``VIDIOC_SUBDEV_G_ROUTING`` ioctl and application may enable or disable routes +with the ``VIDIOC_SUBDEV_S_ROUTING`` ioctl, by adding or removing routes and +setting or clearing flags of the ``flags`` field of a +struct :c:type:`v4l2_subdev_route`. + +All stream configurations are reset when ``VIDIOC_SUBDEV_S_ROUTING`` is called. This +means that the userspace must reconfigure all streams after calling the ioctl +with e.g. ``VIDIOC_SUBDEV_S_FMT``. + +Only subdevices which have both sink and source pads can support routing. + +When inspecting routes through ``VIDIOC_SUBDEV_G_ROUTING`` and the application +provided ``num_routes`` is not big enough to contain all the available routes +the subdevice exposes, drivers return the ENOSPC error code and adjust the +value of the ``num_routes`` field. Application should then reserve enough memory +for all the route entries and call ``VIDIOC_SUBDEV_G_ROUTING`` again. + +On a successful ``VIDIOC_SUBDEV_G_ROUTING`` call the driver updates the +``num_routes`` field to reflect the actual number of routes returned. + +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| + +.. c:type:: v4l2_subdev_routing + +.. flat-table:: struct v4l2_subdev_routing + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + * - __u32 + - ``which`` + - Format to modified, from enum + :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`. + * - struct :c:type:`v4l2_subdev_route` + - ``routes[]`` + - Array of struct :c:type:`v4l2_subdev_route` entries + * - __u32 + - ``num_routes`` + - Number of entries of the routes array + * - __u32 + - ``reserved``\ [5] + - Reserved for future extensions. Applications and drivers must set + the array to zero. + +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| + +.. c:type:: v4l2_subdev_route + +.. flat-table:: struct v4l2_subdev_route + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + * - __u32 + - ``sink_pad`` + - Sink pad number. + * - __u32 + - ``sink_stream`` + - Sink pad stream number. + * - __u32 + - ``source_pad`` + - Source pad number. + * - __u32 + - ``source_stream`` + - Source pad stream number. + * - __u32 + - ``flags`` + - Route enable/disable flags + :ref:`v4l2_subdev_routing_flags <v4l2-subdev-routing-flags>`. + * - __u32 + - ``reserved``\ [5] + - Reserved for future extensions. Applications and drivers must set + the array to zero. + +.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| + +.. _v4l2-subdev-routing-flags: + +.. flat-table:: enum v4l2_subdev_routing_flags + :header-rows: 0 + :stub-columns: 0 + :widths: 3 1 4 + + * - V4L2_SUBDEV_ROUTE_FL_ACTIVE + - 0x0001 + - The route is enabled. Set by applications. + +Return Value +============ + +On success 0 is returned, on error -1 and the ``errno`` variable is set +appropriately. The generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. + +ENOSPC + The application provided ``num_routes`` is not big enough to contain + all the available routes the subdevice exposes. + +EINVAL + The sink or source pad identifiers reference a non-existing pad, or reference + pads of different types (ie. the sink_pad identifiers refers to a source pad). + +E2BIG + The application provided ``num_routes`` for ``VIDIOC_SUBDEV_S_ROUTING`` is + larger than the number of routes the driver can handle. |