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1 | .. -*- coding: utf-8; mode: rst -*- |
2 | ||
af4a4d0d | 3 | .. _VIDIOC_G_EDID: |
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4 | |
5 | ****************************************************************************** | |
6 | ioctl VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, VIDIOC_SUBDEV_S_EDID | |
7 | ****************************************************************************** | |
8 | ||
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9 | NAME |
10 | ==== | |
5377d91f | 11 | |
586027ce | 12 | VIDIOC_G_EDID - VIDIOC_S_EDID - VIDIOC_SUBDEV_G_EDID - VIDIOC_SUBDEV_S_EDID - Get or set the EDID of a video receiver/transmitter |
5377d91f | 13 | |
586027ce | 14 | SYNOPSIS |
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15 | ======== |
16 | ||
b7e67f6c | 17 | .. cpp:function:: int ioctl( int fd, int request, struct v4l2_edid *argp ) |
5377d91f | 18 | |
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19 | |
20 | ARGUMENTS | |
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21 | ========= |
22 | ||
23 | ``fd`` | |
24 | File descriptor returned by :ref:`open() <func-open>`. | |
25 | ||
26 | ``request`` | |
27 | VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, | |
28 | VIDIOC_SUBDEV_S_EDID | |
29 | ||
30 | ``argp`` | |
31 | ||
32 | ||
586027ce | 33 | DESCRIPTION |
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34 | =========== |
35 | ||
36 | These ioctls can be used to get or set an EDID associated with an input | |
37 | from a receiver or an output of a transmitter device. They can be used | |
38 | with subdevice nodes (/dev/v4l-subdevX) or with video nodes | |
39 | (/dev/videoX). | |
40 | ||
41 | When used with video nodes the ``pad`` field represents the input (for | |
42 | video capture devices) or output (for video output devices) index as is | |
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43 | returned by :ref:`VIDIOC_ENUMINPUT` and |
44 | :ref:`VIDIOC_ENUMOUTPUT` respectively. When used | |
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45 | with subdevice nodes the ``pad`` field represents the input or output |
46 | pad of the subdevice. If there is no EDID support for the given ``pad`` | |
cdb4af0f | 47 | value, then the ``EINVAL`` error code will be returned. |
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48 | |
49 | To get the EDID data the application has to fill in the ``pad``, | |
50 | ``start_block``, ``blocks`` and ``edid`` fields, zero the ``reserved`` | |
4e03cb76 | 51 | array and call :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>`. The current EDID from block |
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52 | ``start_block`` and of size ``blocks`` will be placed in the memory |
53 | ``edid`` points to. The ``edid`` pointer must point to memory at least | |
54 | ``blocks`` * 128 bytes large (the size of one block is 128 bytes). | |
55 | ||
56 | If there are fewer blocks than specified, then the driver will set | |
57 | ``blocks`` to the actual number of blocks. If there are no EDID blocks | |
cdb4af0f | 58 | available at all, then the error code ``ENODATA`` is set. |
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59 | |
60 | If blocks have to be retrieved from the sink, then this call will block | |
61 | until they have been read. | |
62 | ||
63 | If ``start_block`` and ``blocks`` are both set to 0 when | |
4e03cb76 | 64 | :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>` is called, then the driver will set ``blocks`` to the |
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65 | total number of available EDID blocks and it will return 0 without |
66 | copying any data. This is an easy way to discover how many EDID blocks | |
67 | there are. Note that if there are no EDID blocks available at all, then | |
68 | the driver will set ``blocks`` to 0 and it returns 0. | |
69 | ||
70 | To set the EDID blocks of a receiver the application has to fill in the | |
71 | ``pad``, ``blocks`` and ``edid`` fields, set ``start_block`` to 0 and | |
72 | zero the ``reserved`` array. It is not possible to set part of an EDID, | |
73 | it is always all or nothing. Setting the EDID data is only valid for | |
74 | receivers as it makes no sense for a transmitter. | |
75 | ||
76 | The driver assumes that the full EDID is passed in. If there are more | |
77 | EDID blocks than the hardware can handle then the EDID is not written, | |
cdb4af0f | 78 | but instead the error code ``E2BIG`` is set and ``blocks`` is set to the |
5377d91f | 79 | maximum that the hardware supports. If ``start_block`` is any value |
cdb4af0f | 80 | other than 0 then the error code ``EINVAL`` is set. |
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81 | |
82 | To disable an EDID you set ``blocks`` to 0. Depending on the hardware | |
83 | this will drive the hotplug pin low and/or block the source from reading | |
84 | the EDID data in some way. In any case, the end result is the same: the | |
85 | EDID is no longer available. | |
86 | ||
87 | ||
88 | .. _v4l2-edid: | |
89 | ||
90 | .. flat-table:: struct v4l2_edid | |
91 | :header-rows: 0 | |
92 | :stub-columns: 0 | |
93 | :widths: 1 1 2 | |
94 | ||
95 | ||
96 | - .. row 1 | |
97 | ||
98 | - __u32 | |
99 | ||
100 | - ``pad`` | |
101 | ||
102 | - Pad for which to get/set the EDID blocks. When used with a video | |
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103 | device node the pad represents the input or output index as |
104 | returned by :ref:`VIDIOC_ENUMINPUT` and | |
105 | :ref:`VIDIOC_ENUMOUTPUT` respectively. | |
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106 | |
107 | - .. row 2 | |
108 | ||
109 | - __u32 | |
110 | ||
111 | - ``start_block`` | |
112 | ||
113 | - Read the EDID from starting with this block. Must be 0 when | |
0579e6e3 | 114 | setting the EDID. |
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115 | |
116 | - .. row 3 | |
117 | ||
118 | - __u32 | |
119 | ||
120 | - ``blocks`` | |
121 | ||
122 | - The number of blocks to get or set. Must be less or equal to 256 | |
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123 | (the maximum number of blocks as defined by the standard). When |
124 | you set the EDID and ``blocks`` is 0, then the EDID is disabled or | |
125 | erased. | |
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126 | |
127 | - .. row 4 | |
128 | ||
129 | - __u32 | |
130 | ||
131 | - ``reserved``\ [5] | |
132 | ||
133 | - Reserved for future extensions. Applications and drivers must set | |
0579e6e3 | 134 | the array to zero. |
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135 | |
136 | - .. row 5 | |
137 | ||
138 | - __u8 * | |
139 | ||
140 | - ``edid`` | |
141 | ||
142 | - Pointer to memory that contains the EDID. The minimum size is | |
0579e6e3 | 143 | ``blocks`` * 128. |
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144 | |
145 | ||
586027ce | 146 | RETURN VALUE |
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147 | ============ |
148 | ||
149 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
150 | appropriately. The generic error codes are described at the | |
151 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
152 | ||
cdb4af0f | 153 | ``ENODATA`` |
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154 | The EDID data is not available. |
155 | ||
cdb4af0f | 156 | ``E2BIG`` |
5377d91f | 157 | The EDID data you provided is more than the hardware can handle. |