Add documentation for VIDIOC_SUBDEV_G/S_ROUTING ioctl and add description of multiplexed media pads and internal routing to the V4L2-subdev documentation section.
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| @@ -29,6 +29,8 @@ will feature a character device node on which ioctls can be called to · 28 unmodified lines | ||
| 29 | 29 | |
| 30 | 30 | - negotiate image formats on individual pads |
| 31 | 31 | |
| 32 | +- inspect and modify internal data routing between pads of the same entity | |
| 33 | + | |
| 32 | 34 | Sub-device character device nodes, conventionally named |
| 33 | 35 | ``/dev/v4l-subdev*``, use major number 81. |
| 34 | 36 | |
| @@ -70,6 +70,7 @@ Function Reference · 69 unmodified lines | ||
| 70 | 70 | vidioc-subdev-g-crop |
| 71 | 71 | vidioc-subdev-g-fmt |
| 72 | 72 | vidioc-subdev-g-frame-interval |
| 73 | + vidioc-subdev-g-routing | |
| 73 | 74 | vidioc-subdev-g-selection |
| 74 | 75 | vidioc-subdev-querycap |
| 75 | 76 | vidioc-subscribe-event |
| @@ -0,0 +1,147 @@ | ||
| 1 | +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later | |
| 2 | +.. c:namespace:: V4L | |
| 3 | + | |
| 4 | +.. _VIDIOC_SUBDEV_G_ROUTING: | |
| 5 | + | |
| 6 | +****************************************************** | |
| 7 | +ioctl VIDIOC_SUBDEV_G_ROUTING, VIDIOC_SUBDEV_S_ROUTING | |
| 8 | +****************************************************** | |
| 9 | + | |
| 10 | +Name | |
| 11 | +==== | |
| 12 | + | |
| 13 | +VIDIOC_SUBDEV_G_ROUTING - VIDIOC_SUBDEV_S_ROUTING - Get or set routing between streams of media pads in a media entity. | |
| 14 | + | |
| 15 | + | |
| 16 | +Synopsis | |
| 17 | +======== | |
| 18 | + | |
| 19 | +.. c:macro:: VIDIOC_SUBDEV_G_ROUTING | |
| 20 | + | |
| 21 | +``int ioctl(int fd, VIDIOC_SUBDEV_G_ROUTING, struct v4l2_subdev_routing *argp)`` | |
| 22 | + | |
| 23 | +.. c:macro:: VIDIOC_SUBDEV_S_ROUTING | |
| 24 | + | |
| 25 | +``int ioctl(int fd, VIDIOC_SUBDEV_S_ROUTING, struct v4l2_subdev_routing *argp)`` | |
| 26 | + | |
| 27 | +Arguments | |
| 28 | +========= | |
| 29 | + | |
| 30 | +``fd`` | |
| 31 | + File descriptor returned by :ref:`open() <func-open>`. | |
| 32 | + | |
| 33 | +``argp`` | |
| 34 | + Pointer to struct :c:type:`v4l2_subdev_routing`. | |
| 35 | + | |
| 36 | + | |
| 37 | +Description | |
| 38 | +=========== | |
| 39 | + | |
| 40 | +These ioctls are used to get and set the routing in a media entity. | |
| 41 | +The routing configuration determines the flows of data inside an entity. | |
| 42 | + | |
| 43 | +Drivers report their current routing tables using the | |
| 44 | +``VIDIOC_SUBDEV_G_ROUTING`` ioctl and application may enable or disable routes | |
| 45 | +with the ``VIDIOC_SUBDEV_S_ROUTING`` ioctl, by adding or removing routes and | |
| 46 | +setting or clearing flags of the ``flags`` field of a | |
| 47 | +struct :c:type:`v4l2_subdev_route`. | |
| 48 | + | |
| 49 | +All stream configurations are reset when ``VIDIOC_SUBDEV_S_ROUTING`` is called. This | |
| 50 | +means that the userspace must reconfigure all streams after calling the ioctl | |
| 51 | +with e.g. ``VIDIOC_SUBDEV_S_FMT``. | |
| 52 | + | |
| 53 | +Only subdevices which have both sink and source pads can support routing. | |
| 54 | + | |
| 55 | +When inspecting routes through ``VIDIOC_SUBDEV_G_ROUTING`` and the application | |
| 56 | +provided ``num_routes`` is not big enough to contain all the available routes | |
| 57 | +the subdevice exposes, drivers return the ENOSPC error code and adjust the | |
| 58 | +value of the ``num_routes`` field. Application should then reserve enough memory | |
| 59 | +for all the route entries and call ``VIDIOC_SUBDEV_G_ROUTING`` again. | |
| 60 | + | |
| 61 | +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| | |
| 62 | + | |
| 63 | +.. c:type:: v4l2_subdev_routing | |
| 64 | + | |
| 65 | +.. flat-table:: struct v4l2_subdev_routing | |
| 66 | + :header-rows: 0 | |
| 67 | + :stub-columns: 0 | |
| 68 | + :widths: 1 1 2 | |
| 69 | + | |
| 70 | + * - __u32 | |
| 71 | + - ``which`` | |
| 72 | + - Format to modified, from enum | |
| 73 | + :ref:`v4l2_subdev_format_whence <v4l2-subdev-format-whence>`. | |
| 74 | + * - struct :c:type:`v4l2_subdev_route` | |
| 75 | + - ``routes[]`` | |
| 76 | + - Array of struct :c:type:`v4l2_subdev_route` entries | |
| 77 | + * - __u32 | |
| 78 | + - ``num_routes`` | |
| 79 | + - Number of entries of the routes array | |
| 80 | + * - __u32 | |
| 81 | + - ``reserved``\ [5] | |
| 82 | + - Reserved for future extensions. Applications and drivers must set | |
| 83 | + the array to zero. | |
| 84 | + | |
| 85 | +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| | |
| 86 | + | |
| 87 | +.. c:type:: v4l2_subdev_route | |
| 88 | + | |
| 89 | +.. flat-table:: struct v4l2_subdev_route | |
| 90 | + :header-rows: 0 | |
| 91 | + :stub-columns: 0 | |
| 92 | + :widths: 1 1 2 | |
| 93 | + | |
| 94 | + * - __u32 | |
| 95 | + - ``sink_pad`` | |
| 96 | + - Sink pad number. | |
| 97 | + * - __u32 | |
| 98 | + - ``sink_stream`` | |
| 99 | + - Sink pad stream number. | |
| 100 | + * - __u32 | |
| 101 | + - ``source_pad`` | |
| 102 | + - Source pad number. | |
| 103 | + * - __u32 | |
| 104 | + - ``source_stream`` | |
| 105 | + - Source pad stream number. | |
| 106 | + * - __u32 | |
| 107 | + - ``flags`` | |
| 108 | + - Route enable/disable flags | |
| 109 | + :ref:`v4l2_subdev_routing_flags <v4l2-subdev-routing-flags>`. | |
| 110 | + * - __u32 | |
| 111 | + - ``reserved``\ [5] | |
| 112 | + - Reserved for future extensions. Applications and drivers must set | |
| 113 | + the array to zero. | |
| 114 | + | |
| 115 | +.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}| | |
| 116 | + | |
| 117 | +.. _v4l2-subdev-routing-flags: | |
| 118 | + | |
| 119 | +.. flat-table:: enum v4l2_subdev_routing_flags | |
| 120 | + :header-rows: 0 | |
| 121 | + :stub-columns: 0 | |
| 122 | + :widths: 3 1 4 | |
| 123 | + | |
| 124 | + * - V4L2_SUBDEV_ROUTE_FL_ACTIVE | |
| 125 | + - 0 | |
| 126 | + - The route is enabled. Set by applications. | |
| 127 | + | |
| 128 | +Return Value | |
| 129 | +============ | |
| 130 | + | |
| 131 | +On success 0 is returned, on error -1 and the ``errno`` variable is set | |
| 132 | +appropriately. The generic error codes are described at the | |
| 133 | +:ref:`Generic Error Codes <gen-errors>` chapter. | |
| 134 | + | |
| 135 | +ENOSPC | |
| 136 | + The application provided ``num_routes`` is not big enough to contain | |
| 137 | + all the available routes the subdevice exposes. | |
| 138 | + | |
| 139 | +EINVAL | |
| 140 | + The sink or source pad identifiers reference a non-existing pad, or reference | |
| 141 | + pads of different types (ie. the sink_pad identifiers refers to a source pad) | |
| 142 | + or the sink or source stream identifiers reference a non-existing stream on | |
| 143 | + the sink or source pad. | |
| 144 | + | |
| 145 | +E2BIG | |
| 146 | + The application provided ``num_routes`` for ``VIDIOC_SUBDEV_S_ROUTING`` is | |
| 147 | + larger than the number of routes the driver can handle. | |