1 .. -*- coding: utf-8; mode: rst -*-
5 ******************************************************************************
6 ioctl VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, VIDIOC_SUBDEV_S_EDID
7 ******************************************************************************
14 Get or set the EDID of a video receiver/transmitter
20 .. c:function:: int ioctl( int fd, int request, struct v4l2_edid *argp )
22 .. c:function:: int ioctl( int fd, int request, struct v4l2_edid *argp )
28 File descriptor returned by :ref:`open() <func-open>`.
31 VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID,
40 These ioctls can be used to get or set an EDID associated with an input
41 from a receiver or an output of a transmitter device. They can be used
42 with subdevice nodes (/dev/v4l-subdevX) or with video nodes
45 When used with video nodes the ``pad`` field represents the input (for
46 video capture devices) or output (for video output devices) index as is
47 returned by :ref:`VIDIOC_ENUMINPUT <VIDIOC_ENUMINPUT>` and
48 :ref:`VIDIOC_ENUMOUTPUT <VIDIOC_ENUMOUTPUT>` respectively. When used
49 with subdevice nodes the ``pad`` field represents the input or output
50 pad of the subdevice. If there is no EDID support for the given ``pad``
51 value, then the EINVAL error code will be returned.
53 To get the EDID data the application has to fill in the ``pad``,
54 ``start_block``, ``blocks`` and ``edid`` fields, zero the ``reserved``
55 array and call ``VIDIOC_G_EDID``. The current EDID from block
56 ``start_block`` and of size ``blocks`` will be placed in the memory
57 ``edid`` points to. The ``edid`` pointer must point to memory at least
58 ``blocks`` * 128 bytes large (the size of one block is 128 bytes).
60 If there are fewer blocks than specified, then the driver will set
61 ``blocks`` to the actual number of blocks. If there are no EDID blocks
62 available at all, then the error code ENODATA is set.
64 If blocks have to be retrieved from the sink, then this call will block
65 until they have been read.
67 If ``start_block`` and ``blocks`` are both set to 0 when
68 ``VIDIOC_G_EDID`` is called, then the driver will set ``blocks`` to the
69 total number of available EDID blocks and it will return 0 without
70 copying any data. This is an easy way to discover how many EDID blocks
71 there are. Note that if there are no EDID blocks available at all, then
72 the driver will set ``blocks`` to 0 and it returns 0.
74 To set the EDID blocks of a receiver the application has to fill in the
75 ``pad``, ``blocks`` and ``edid`` fields, set ``start_block`` to 0 and
76 zero the ``reserved`` array. It is not possible to set part of an EDID,
77 it is always all or nothing. Setting the EDID data is only valid for
78 receivers as it makes no sense for a transmitter.
80 The driver assumes that the full EDID is passed in. If there are more
81 EDID blocks than the hardware can handle then the EDID is not written,
82 but instead the error code E2BIG is set and ``blocks`` is set to the
83 maximum that the hardware supports. If ``start_block`` is any value
84 other than 0 then the error code EINVAL is set.
86 To disable an EDID you set ``blocks`` to 0. Depending on the hardware
87 this will drive the hotplug pin low and/or block the source from reading
88 the EDID data in some way. In any case, the end result is the same: the
89 EDID is no longer available.
94 .. flat-table:: struct v4l2_edid
106 - Pad for which to get/set the EDID blocks. When used with a video
107 device node the pad represents the input or output index as
108 returned by :ref:`VIDIOC_ENUMINPUT <VIDIOC_ENUMINPUT>` and
109 :ref:`VIDIOC_ENUMOUTPUT <VIDIOC_ENUMOUTPUT>` respectively.
117 - Read the EDID from starting with this block. Must be 0 when
126 - The number of blocks to get or set. Must be less or equal to 256
127 (the maximum number of blocks as defined by the standard). When
128 you set the EDID and ``blocks`` is 0, then the EDID is disabled or
137 - Reserved for future extensions. Applications and drivers must set
146 - Pointer to memory that contains the EDID. The minimum size is
154 On success 0 is returned, on error -1 and the ``errno`` variable is set
155 appropriately. The generic error codes are described at the
156 :ref:`Generic Error Codes <gen-errors>` chapter.
159 The EDID data is not available.
162 The EDID data you provided is more than the hardware can handle.
165 .. ------------------------------------------------------------------------------
166 .. This file was automatically converted from DocBook-XML with the dbxml
167 .. library (https://github.com/return42/sphkerneldoc). The origin XML comes
168 .. from the linux kernel, refer to:
170 .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
171 .. ------------------------------------------------------------------------------