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1 | .. -*- coding: utf-8; mode: rst -*- |
2 | ||
3 | .. _vidioc-g-edid: | |
4 | ||
5 | ****************************************************************************** | |
6 | ioctl VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, VIDIOC_SUBDEV_S_EDID | |
7 | ****************************************************************************** | |
8 | ||
9 | *man VIDIOC_G_EDID(2)* | |
10 | ||
11 | VIDIOC_S_EDID | |
12 | VIDIOC_SUBDEV_G_EDID | |
13 | VIDIOC_SUBDEV_S_EDID | |
14 | Get or set the EDID of a video receiver/transmitter | |
15 | ||
16 | ||
17 | Synopsis | |
18 | ======== | |
19 | ||
20 | .. c:function:: int ioctl( int fd, int request, struct v4l2_edid *argp ) | |
21 | ||
22 | .. c:function:: int ioctl( int fd, int request, struct v4l2_edid *argp ) | |
23 | ||
24 | Arguments | |
25 | ========= | |
26 | ||
27 | ``fd`` | |
28 | File descriptor returned by :ref:`open() <func-open>`. | |
29 | ||
30 | ``request`` | |
31 | VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, | |
32 | VIDIOC_SUBDEV_S_EDID | |
33 | ||
34 | ``argp`` | |
35 | ||
36 | ||
37 | Description | |
38 | =========== | |
39 | ||
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 | |
43 | (/dev/videoX). | |
44 | ||
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. | |
52 | ||
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). | |
59 | ||
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. | |
63 | ||
64 | If blocks have to be retrieved from the sink, then this call will block | |
65 | until they have been read. | |
66 | ||
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. | |
73 | ||
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. | |
79 | ||
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. | |
85 | ||
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. | |
90 | ||
91 | ||
92 | .. _v4l2-edid: | |
93 | ||
94 | .. flat-table:: struct v4l2_edid | |
95 | :header-rows: 0 | |
96 | :stub-columns: 0 | |
97 | :widths: 1 1 2 | |
98 | ||
99 | ||
100 | - .. row 1 | |
101 | ||
102 | - __u32 | |
103 | ||
104 | - ``pad`` | |
105 | ||
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. | |
110 | ||
111 | - .. row 2 | |
112 | ||
113 | - __u32 | |
114 | ||
115 | - ``start_block`` | |
116 | ||
117 | - Read the EDID from starting with this block. Must be 0 when | |
118 | setting the EDID. | |
119 | ||
120 | - .. row 3 | |
121 | ||
122 | - __u32 | |
123 | ||
124 | - ``blocks`` | |
125 | ||
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 | |
129 | erased. | |
130 | ||
131 | - .. row 4 | |
132 | ||
133 | - __u32 | |
134 | ||
135 | - ``reserved``\ [5] | |
136 | ||
137 | - Reserved for future extensions. Applications and drivers must set | |
138 | the array to zero. | |
139 | ||
140 | - .. row 5 | |
141 | ||
142 | - __u8 * | |
143 | ||
144 | - ``edid`` | |
145 | ||
146 | - Pointer to memory that contains the EDID. The minimum size is | |
147 | ``blocks`` * 128. | |
148 | ||
149 | ||
150 | ||
151 | Return Value | |
152 | ============ | |
153 | ||
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. | |
157 | ||
158 | ENODATA | |
159 | The EDID data is not available. | |
160 | ||
161 | E2BIG | |
162 | The EDID data you provided is more than the hardware can handle. | |
163 | ||
164 | ||
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: | |
169 | .. | |
170 | .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook | |
171 | .. ------------------------------------------------------------------------------ |