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authorThomas Zimmermann <tzimmermann@suse.de>2023-03-13 09:27:50 +0100
committerThomas Zimmermann <tzimmermann@suse.de>2023-03-13 09:27:50 +0100
commita1eccc574f977bd21a4ec8ac54bd73a2756bd281 (patch)
tree4bf81d9f35b36aebb150128e865193bf8984bf8c /Documentation/userspace-api/media/v4l
parent3e853b9f89e4bcc8aa342fa350d83ff0df67d7e9 (diff)
parentfe15c26ee26efa11741a7b632e9f23b01aca4cc6 (diff)
Merge drm/drm-next into drm-misc-next
Backmerging to get v6.3-rc1 and sync with the other DRM trees. Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Diffstat (limited to 'Documentation/userspace-api/media/v4l')
-rw-r--r--Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst2
-rw-r--r--Documentation/userspace-api/media/v4l/dev-subdev.rst166
-rw-r--r--Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst2
-rw-r--r--Documentation/userspace-api/media/v4l/ext-ctrls-jpeg.rst2
-rw-r--r--Documentation/userspace-api/media/v4l/hist-v4l2.rst4
-rw-r--r--Documentation/userspace-api/media/v4l/pixfmt-reserved.rst2
-rw-r--r--Documentation/userspace-api/media/v4l/pixfmt-yuv-luma.rst2
-rw-r--r--Documentation/userspace-api/media/v4l/user-func.rst1
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-cropcap.rst2
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-interval.rst5
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst5
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst5
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst5
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-subdev-g-fmt.rst5
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-subdev-g-frame-interval.rst5
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-subdev-g-routing.rst147
-rw-r--r--Documentation/userspace-api/media/v4l/vidioc-subdev-g-selection.rst5
17 files changed, 350 insertions, 15 deletions
diff --git a/Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst b/Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst
index 44415822c7c5..42cdb0a9f786 100644
--- a/Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst
+++ b/Documentation/userspace-api/media/v4l/dev-sliced-vbi.rst
@@ -490,7 +490,7 @@ struct v4l2_mpeg_vbi_fmt_ivtv
- An alternate form of the sliced VBI data payload used when 36
lines of sliced VBI data are present. No line masks are provided
in this form of the payload; all valid line mask bits are
- implcitly set.
+ implicitly set.
* - }
-
diff --git a/Documentation/userspace-api/media/v4l/dev-subdev.rst b/Documentation/userspace-api/media/v4l/dev-subdev.rst
index fd1de0a73a9f..a4f1df7093e8 100644
--- a/Documentation/userspace-api/media/v4l/dev-subdev.rst
+++ b/Documentation/userspace-api/media/v4l/dev-subdev.rst
@@ -29,6 +29,8 @@ will feature a character device node on which ioctls can be called to
- negotiate image formats on individual pads
+- inspect and modify internal data routing between pads of the same entity
+
Sub-device character device nodes, conventionally named
``/dev/v4l-subdev*``, use major number 81.
@@ -404,6 +406,8 @@ pixel array is not rectangular but cross-shaped or round. The maximum
size may also be smaller than the BOUNDS rectangle.
+.. _format-propagation:
+
Order of configuration and format propagation
---------------------------------------------
@@ -501,3 +505,165 @@ source pads.
:maxdepth: 1
subdev-formats
+
+Streams, multiplexed media pads and internal routing
+----------------------------------------------------
+
+Simple V4L2 sub-devices do not support multiple, unrelated video streams,
+and only a single stream can pass through a media link and a media pad.
+Thus each pad contains a format and selection configuration for that
+single stream. A subdev can do stream processing and split a stream into
+two or compose two streams into one, but the inputs and outputs for the
+subdev are still a single stream per pad.
+
+Some hardware, e.g. MIPI CSI-2, support multiplexed streams, that is, multiple
+data streams are transmitted on the same bus, which is represented by a media
+link connecting a transmitter source pad with a sink pad on the receiver. For
+example, a camera sensor can produce two distinct streams, a pixel stream and a
+metadata stream, which are transmitted on the multiplexed data bus, represented
+by a media link which connects the single sensor's source pad with the receiver
+sink pad. The stream-aware receiver will de-multiplex the streams received on
+the its sink pad and allows to route them individually to one of its source
+pads.
+
+Subdevice drivers that support multiplexed streams are compatible with
+non-multiplexed subdev drivers, but, of course, require a routing configuration
+where the link between those two types of drivers contains only a single
+stream.
+
+Understanding streams
+^^^^^^^^^^^^^^^^^^^^^
+
+A stream is a stream of content (e.g. pixel data or metadata) flowing through
+the media pipeline from a source (e.g. a sensor) towards the final sink (e.g. a
+receiver and demultiplexer in a SoC). Each media link carries all the enabled
+streams from one end of the link to the other, and sub-devices have routing
+tables which describe how the incoming streams from sink pads are routed to the
+source pads.
+
+A stream ID is a media pad-local identifier for a stream. Streams IDs of
+the same stream must be equal on both ends of a link. In other words,
+a particular stream ID must exist on both sides of a media
+link, but another stream ID can be used for the same stream at the other side
+of the sub-device.
+
+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.
+
+Interaction between routes, streams, formats and selections
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The addition of streams to the V4L2 sub-device interface moves the sub-device
+formats and selections from pads to (pad, stream) pairs. Besides the
+usual pad, also the stream ID needs to be provided for setting formats and
+selections. The order of configuring formats and selections along a stream is
+the same as without streams (see :ref:`format-propagation`).
+
+Instead of the sub-device wide merging of streams from all sink pads
+towards all source pads, data flows for each route are separate from each
+other. Any number of routes from streams on sink pads towards streams on
+source pads is allowed, to the extent supported by drivers. For every
+stream on a source pad, however, only a single route is allowed.
+
+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.
+
+Configuring streams
+^^^^^^^^^^^^^^^^^^^
+
+The configuration of the streams is done individually for each sub-device and
+the validity of the streams between sub-devices is validated when the pipeline
+is started.
+
+There are three steps in configuring the streams:
+
+1) Set up links. Connect the pads between sub-devices using the :ref:`Media
+Controller API <media_controller>`
+
+2) Streams. Streams are declared and their routing is configured by
+setting the routing table for the sub-device using
+:ref:`VIDIOC_SUBDEV_S_ROUTING <VIDIOC_SUBDEV_G_ROUTING>` ioctl. Note that
+setting the routing table will reset formats and selections in the
+sub-device to default values.
+
+3) Configure formats and selections. Formats and selections of each stream
+are configured separately as documented for plain sub-devices in
+:ref:`format-propagation`. The stream ID is set to the same stream ID
+associated with either sink or source pads of routes configured using the
+:ref:`VIDIOC_SUBDEV_S_ROUTING <VIDIOC_SUBDEV_G_ROUTING>` ioctl.
+
+Multiplexed streams setup example
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+A simple example of a multiplexed stream setup might be as follows:
+
+- Two identical sensors (Sensor A and Sensor B). Each sensor has a single source
+ pad (pad 0) which carries a pixel data stream.
+
+- Multiplexer bridge (Bridge). The bridge has two sink pads, connected to the
+ sensors (pads 0, 1), and one source pad (pad 2), which outputs two streams.
+
+- Receiver in the SoC (Receiver). The receiver has a single sink pad (pad 0),
+ connected to the bridge, and two source pads (pads 1-2), going to the DMA
+ engine. The receiver demultiplexes the incoming streams to the source pads.
+
+- DMA Engines in the SoC (DMA Engine), one for each stream. Each DMA engine is
+ connected to a single source pad in the receiver.
+
+The sensors, the bridge and the receiver are modeled as V4L2 sub-devices,
+exposed to userspace via /dev/v4l-subdevX device nodes. The DMA engines are
+modeled 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: connect the sensors to the bridge,
+bridge to the receiver, and the receiver to the DMA engines. This step does
+not differ from normal non-multiplexed media controller setup.
+
+2) Configure routing
+
+.. flat-table:: Bridge routing table
+ :header-rows: 1
+
+ * - Sink Pad/Stream
+ - Source Pad/Stream
+ - Routing Flags
+ - Comments
+ * - 0/0
+ - 2/0
+ - V4L2_SUBDEV_ROUTE_FL_ACTIVE
+ - Pixel data stream from Sensor A
+ * - 1/0
+ - 2/1
+ - V4L2_SUBDEV_ROUTE_FL_ACTIVE
+ - Pixel data stream from Sensor B
+
+.. flat-table:: Receiver routing table
+ :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 Sensor A
+ * - 0/1
+ - 2/0
+ - V4L2_SUBDEV_ROUTE_FL_ACTIVE
+ - Pixel data stream from Sensor B
+
+3) Configure formats and selections
+
+After configuring routing, the next step is configuring the formats and
+selections for the streams. This is similar to performing this step without
+streams, with just one exception: the ``stream`` field needs to be assigned
+to the value of the stream ID.
+
+A common way to accomplish this is to start from the sensors and propagate 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.
diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
index cd33857d947d..3d8411acd5b8 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst
@@ -1213,7 +1213,7 @@ FWHT Flags
- Luma AC coefficient table index.
* - __s8
- ``y_dc_delta``
- - Luma DC delta vaue.
+ - Luma DC delta value.
* - __s8
- ``y2_dc_delta``
- Y2 block DC delta value.
diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-jpeg.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-jpeg.rst
index 60f9a09422d6..522095c08469 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-jpeg.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-jpeg.rst
@@ -8,7 +8,7 @@ JPEG Control Reference
The JPEG class includes controls for common features of JPEG encoders
and decoders. Currently it includes features for codecs implementing
-progressive baseline DCT compression process with Huffman entrophy
+progressive baseline DCT compression process with Huffman entropy
coding.
diff --git a/Documentation/userspace-api/media/v4l/hist-v4l2.rst b/Documentation/userspace-api/media/v4l/hist-v4l2.rst
index dbc04374dc22..cdc11e9a0f32 100644
--- a/Documentation/userspace-api/media/v4l/hist-v4l2.rst
+++ b/Documentation/userspace-api/media/v4l/hist-v4l2.rst
@@ -47,7 +47,7 @@ Codec API was released.
1998-11-08: Many minor changes. Most symbols have been renamed. Some
material changes to struct v4l2_capability.
-1998-11-12: The read/write directon of some ioctls was misdefined.
+1998-11-12: The read/write direction of some ioctls was misdefined.
1998-11-14: ``V4L2_PIX_FMT_RGB24`` changed to ``V4L2_PIX_FMT_BGR24``,
and ``V4L2_PIX_FMT_RGB32`` changed to ``V4L2_PIX_FMT_BGR32``. Audio
@@ -145,7 +145,7 @@ common Linux driver API conventions.
``VIDIOC_G_INFMT``, ``VIDIOC_S_OUTFMT``, ``VIDIOC_G_OUTFMT``,
``VIDIOC_S_VBIFMT`` and ``VIDIOC_G_VBIFMT``. The image format
struct v4l2_format was renamed to struct v4l2_pix_format, while
- struct v4l2_format is now the envelopping structure
+ struct v4l2_format is now the enveloping structure
for all format negotiations.
5. Similar to the changes above, the ``VIDIOC_G_PARM`` and
diff --git a/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst b/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
index 73cd99828010..58f6ae25b2e7 100644
--- a/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
+++ b/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
@@ -271,7 +271,7 @@ please make a proposal on the linux-media mailing list.
The implementation is based on AST2600 A3 datasheet, revision 0.9, which
is not publicly available. Or you can reference Video stream data format
– ASPEED mode compression of SDK_User_Guide which available on
- AspeedTech-BMC/openbmc/releases.
+ `github <https://github.com/AspeedTech-BMC/openbmc/releases/>`__.
Decoder's implementation can be found here,
`aspeed_codec <https://github.com/AspeedTech-BMC/aspeed_codec/>`__
diff --git a/Documentation/userspace-api/media/v4l/pixfmt-yuv-luma.rst b/Documentation/userspace-api/media/v4l/pixfmt-yuv-luma.rst
index 6a387f9df3ba..62078a01de76 100644
--- a/Documentation/userspace-api/media/v4l/pixfmt-yuv-luma.rst
+++ b/Documentation/userspace-api/media/v4l/pixfmt-yuv-luma.rst
@@ -14,7 +14,7 @@ are often referred to as greyscale formats.
- In all the tables that follow, bit 7 is the most significant bit in a byte.
- Formats are described with the minimum number of pixels needed to create a
byte-aligned repeating pattern. `...` indicates repetition of the pattern.
- - Y'\ :sub:`x`\ [9:2] denotes bits 9 to 2 of the Y' value for pixel at colum
+ - Y'\ :sub:`x`\ [9:2] denotes bits 9 to 2 of the Y' value for pixel at column
`x`.
- `0` denotes padding bits set to 0.
diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst
index 53e604bd7d60..228c1521f190 100644
--- a/Documentation/userspace-api/media/v4l/user-func.rst
+++ b/Documentation/userspace-api/media/v4l/user-func.rst
@@ -70,6 +70,7 @@ Function Reference
vidioc-subdev-g-crop
vidioc-subdev-g-fmt
vidioc-subdev-g-frame-interval
+ vidioc-subdev-g-routing
vidioc-subdev-g-selection
vidioc-subdev-querycap
vidioc-subscribe-event
diff --git a/Documentation/userspace-api/media/v4l/vidioc-cropcap.rst b/Documentation/userspace-api/media/v4l/vidioc-cropcap.rst
index 551ac9d3c6ef..7f10f0bbcfd3 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-cropcap.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-cropcap.rst
@@ -71,7 +71,7 @@ overlay devices.
- Default cropping rectangle, it shall cover the "whole picture".
Assuming pixel aspect 1/1 this could be for example a 640 × 480
rectangle for NTSC, a 768 × 576 rectangle for PAL and SECAM
- centered over the active picture area. The same co-ordinate system
+ centered over the active picture area. The same coordinate system
as for ``bounds`` is used.
* - struct :c:type:`v4l2_fract`
- ``pixelaspect``
diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-interval.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-interval.rst
index 3703943b412f..8def4c05d3da 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-interval.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-interval.rst
@@ -92,7 +92,10 @@ multiple pads of the same sub-device is not defined.
- Frame intervals to be enumerated, from enum
:ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
* - __u32
- - ``reserved``\ [8]
+ - ``stream``
+ - Stream identifier.
+ * - __u32
+ - ``reserved``\ [7]
- Reserved for future extensions. Applications and drivers must set
the array to zero.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst
index c25a9896df0e..3ef361c0dca7 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-frame-size.rst
@@ -97,7 +97,10 @@ information about try formats.
- Frame sizes to be enumerated, from enum
:ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`.
* - __u32
- - ``reserved``\ [8]
+ - ``stream``
+ - Stream identifier.
+ * - __u32
+ - ``reserved``\ [7]
- Reserved for future extensions. Applications and drivers must set
the array to zero.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst
index 417f1a19bcc4..248f6f9ee7c5 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-enum-mbus-code.rst
@@ -73,7 +73,10 @@ information about the try formats.
- ``flags``
- See :ref:`v4l2-subdev-mbus-code-flags`
* - __u32
- - ``reserved``\ [7]
+ - ``stream``
+ - Stream identifier.
+ * - __u32
+ - ``reserved``\ [6]
- Reserved for future extensions. Applications and drivers must set
the array to zero.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst
index bd15c0a5a66b..1d267f7e7991 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-crop.rst
@@ -96,7 +96,10 @@ modified format should be as close as possible to the original request.
- ``rect``
- Crop rectangle boundaries, in pixels.
* - __u32
- - ``reserved``\ [8]
+ - ``stream``
+ - Stream identifier.
+ * - __u32
+ - ``reserved``\ [7]
- Reserved for future extensions. Applications and drivers must set
the array to zero.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-fmt.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-fmt.rst
index 7acdbb939d89..ed253a1e44b7 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-fmt.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-fmt.rst
@@ -102,7 +102,10 @@ should be as close as possible to the original request.
- Definition of an image format, see :c:type:`v4l2_mbus_framefmt` for
details.
* - __u32
- - ``reserved``\ [8]
+ - ``stream``
+ - Stream identifier.
+ * - __u32
+ - ``reserved``\ [7]
- Reserved for future extensions. Applications and drivers must set
the array to zero.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-frame-interval.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-frame-interval.rst
index d7fe7543c506..842f962d2aea 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-frame-interval.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-frame-interval.rst
@@ -90,7 +90,10 @@ the same sub-device is not defined.
- ``interval``
- Period, in seconds, between consecutive video frames.
* - __u32
- - ``reserved``\ [9]
+ - ``stream``
+ - Stream identifier.
+ * - __u32
+ - ``reserved``\ [8]
- Reserved for future extensions. Applications and drivers must set
the array to zero.
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 000000000000..68ca343c3b44
--- /dev/null
+++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-routing.rst
@@ -0,0 +1,147 @@
+.. 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.
+
+.. 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
+ - 0
+ - 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)
+ or the sink or source stream identifiers reference a non-existing stream on
+ the sink or source pad.
+
+E2BIG
+ The application provided ``num_routes`` for ``VIDIOC_SUBDEV_S_ROUTING`` is
+ larger than the number of routes the driver can handle.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-selection.rst b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-selection.rst
index f9172a42f036..6b629c19168c 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-subdev-g-selection.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-subdev-g-selection.rst
@@ -94,7 +94,10 @@ Selection targets and flags are documented in
- ``r``
- Selection rectangle, in pixels.
* - __u32
- - ``reserved``\ [8]
+ - ``stream``
+ - Stream identifier.
+ * - __u32
+ - ``reserved``\ [7]
- Reserved for future extensions. Applications and drivers must set
the array to zero.