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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 | ||
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 | ||
b7e67f6c | 20 | .. cpp:function:: int ioctl( int fd, int request, struct v4l2_edid *argp ) |
5377d91f | 21 | |
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22 | Arguments |
23 | ========= | |
24 | ||
25 | ``fd`` | |
26 | File descriptor returned by :ref:`open() <func-open>`. | |
27 | ||
28 | ``request`` | |
29 | VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, | |
30 | VIDIOC_SUBDEV_S_EDID | |
31 | ||
32 | ``argp`` | |
33 | ||
34 | ||
35 | Description | |
36 | =========== | |
37 | ||
38 | These ioctls can be used to get or set an EDID associated with an input | |
39 | from a receiver or an output of a transmitter device. They can be used | |
40 | with subdevice nodes (/dev/v4l-subdevX) or with video nodes | |
41 | (/dev/videoX). | |
42 | ||
43 | When used with video nodes the ``pad`` field represents the input (for | |
44 | video capture devices) or output (for video output devices) index as is | |
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45 | returned by :ref:`VIDIOC_ENUMINPUT` and |
46 | :ref:`VIDIOC_ENUMOUTPUT` respectively. When used | |
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47 | with subdevice nodes the ``pad`` field represents the input or output |
48 | pad of the subdevice. If there is no EDID support for the given ``pad`` | |
cdb4af0f | 49 | value, then the ``EINVAL`` error code will be returned. |
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50 | |
51 | To get the EDID data the application has to fill in the ``pad``, | |
52 | ``start_block``, ``blocks`` and ``edid`` fields, zero the ``reserved`` | |
4e03cb76 | 53 | array and call :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>`. The current EDID from block |
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54 | ``start_block`` and of size ``blocks`` will be placed in the memory |
55 | ``edid`` points to. The ``edid`` pointer must point to memory at least | |
56 | ``blocks`` * 128 bytes large (the size of one block is 128 bytes). | |
57 | ||
58 | If there are fewer blocks than specified, then the driver will set | |
59 | ``blocks`` to the actual number of blocks. If there are no EDID blocks | |
cdb4af0f | 60 | available at all, then the error code ``ENODATA`` is set. |
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61 | |
62 | If blocks have to be retrieved from the sink, then this call will block | |
63 | until they have been read. | |
64 | ||
65 | If ``start_block`` and ``blocks`` are both set to 0 when | |
4e03cb76 | 66 | :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>` is called, then the driver will set ``blocks`` to the |
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67 | total number of available EDID blocks and it will return 0 without |
68 | copying any data. This is an easy way to discover how many EDID blocks | |
69 | there are. Note that if there are no EDID blocks available at all, then | |
70 | the driver will set ``blocks`` to 0 and it returns 0. | |
71 | ||
72 | To set the EDID blocks of a receiver the application has to fill in the | |
73 | ``pad``, ``blocks`` and ``edid`` fields, set ``start_block`` to 0 and | |
74 | zero the ``reserved`` array. It is not possible to set part of an EDID, | |
75 | it is always all or nothing. Setting the EDID data is only valid for | |
76 | receivers as it makes no sense for a transmitter. | |
77 | ||
78 | The driver assumes that the full EDID is passed in. If there are more | |
79 | EDID blocks than the hardware can handle then the EDID is not written, | |
cdb4af0f | 80 | but instead the error code ``E2BIG`` is set and ``blocks`` is set to the |
5377d91f | 81 | maximum that the hardware supports. If ``start_block`` is any value |
cdb4af0f | 82 | other than 0 then the error code ``EINVAL`` is set. |
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83 | |
84 | To disable an EDID you set ``blocks`` to 0. Depending on the hardware | |
85 | this will drive the hotplug pin low and/or block the source from reading | |
86 | the EDID data in some way. In any case, the end result is the same: the | |
87 | EDID is no longer available. | |
88 | ||
89 | ||
90 | .. _v4l2-edid: | |
91 | ||
92 | .. flat-table:: struct v4l2_edid | |
93 | :header-rows: 0 | |
94 | :stub-columns: 0 | |
95 | :widths: 1 1 2 | |
96 | ||
97 | ||
98 | - .. row 1 | |
99 | ||
100 | - __u32 | |
101 | ||
102 | - ``pad`` | |
103 | ||
104 | - Pad for which to get/set the EDID blocks. When used with a video | |
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105 | device node the pad represents the input or output index as |
106 | returned by :ref:`VIDIOC_ENUMINPUT` and | |
107 | :ref:`VIDIOC_ENUMOUTPUT` respectively. | |
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108 | |
109 | - .. row 2 | |
110 | ||
111 | - __u32 | |
112 | ||
113 | - ``start_block`` | |
114 | ||
115 | - Read the EDID from starting with this block. Must be 0 when | |
0579e6e3 | 116 | setting the EDID. |
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117 | |
118 | - .. row 3 | |
119 | ||
120 | - __u32 | |
121 | ||
122 | - ``blocks`` | |
123 | ||
124 | - The number of blocks to get or set. Must be less or equal to 256 | |
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125 | (the maximum number of blocks as defined by the standard). When |
126 | you set the EDID and ``blocks`` is 0, then the EDID is disabled or | |
127 | erased. | |
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128 | |
129 | - .. row 4 | |
130 | ||
131 | - __u32 | |
132 | ||
133 | - ``reserved``\ [5] | |
134 | ||
135 | - Reserved for future extensions. Applications and drivers must set | |
0579e6e3 | 136 | the array to zero. |
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137 | |
138 | - .. row 5 | |
139 | ||
140 | - __u8 * | |
141 | ||
142 | - ``edid`` | |
143 | ||
144 | - Pointer to memory that contains the EDID. The minimum size is | |
0579e6e3 | 145 | ``blocks`` * 128. |
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146 | |
147 | ||
148 | ||
149 | Return Value | |
150 | ============ | |
151 | ||
152 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
153 | appropriately. The generic error codes are described at the | |
154 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
155 | ||
cdb4af0f | 156 | ``ENODATA`` |
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157 | The EDID data is not available. |
158 | ||
cdb4af0f | 159 | ``E2BIG`` |
5377d91f | 160 | The EDID data you provided is more than the hardware can handle. |