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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 | ||
15e7d615 | 9 | Name |
586027ce | 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 | |
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14 | |
15 | Synopsis | |
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16 | ======== |
17 | ||
b7e67f6c | 18 | .. cpp:function:: int ioctl( int fd, int request, struct v4l2_edid *argp ) |
5377d91f | 19 | |
586027ce | 20 | |
15e7d615 | 21 | Arguments |
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22 | ========= |
23 | ||
24 | ``fd`` | |
25 | File descriptor returned by :ref:`open() <func-open>`. | |
26 | ||
27 | ``request`` | |
28 | VIDIOC_G_EDID, VIDIOC_S_EDID, VIDIOC_SUBDEV_G_EDID, | |
29 | VIDIOC_SUBDEV_S_EDID | |
30 | ||
31 | ``argp`` | |
32 | ||
33 | ||
15e7d615 | 34 | Description |
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35 | =========== |
36 | ||
37 | These ioctls can be used to get or set an EDID associated with an input | |
38 | from a receiver or an output of a transmitter device. They can be used | |
39 | with subdevice nodes (/dev/v4l-subdevX) or with video nodes | |
40 | (/dev/videoX). | |
41 | ||
42 | When used with video nodes the ``pad`` field represents the input (for | |
43 | video capture devices) or output (for video output devices) index as is | |
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44 | returned by :ref:`VIDIOC_ENUMINPUT` and |
45 | :ref:`VIDIOC_ENUMOUTPUT` respectively. When used | |
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46 | with subdevice nodes the ``pad`` field represents the input or output |
47 | pad of the subdevice. If there is no EDID support for the given ``pad`` | |
cdb4af0f | 48 | value, then the ``EINVAL`` error code will be returned. |
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49 | |
50 | To get the EDID data the application has to fill in the ``pad``, | |
51 | ``start_block``, ``blocks`` and ``edid`` fields, zero the ``reserved`` | |
4e03cb76 | 52 | array and call :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>`. The current EDID from block |
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53 | ``start_block`` and of size ``blocks`` will be placed in the memory |
54 | ``edid`` points to. The ``edid`` pointer must point to memory at least | |
55 | ``blocks`` * 128 bytes large (the size of one block is 128 bytes). | |
56 | ||
57 | If there are fewer blocks than specified, then the driver will set | |
58 | ``blocks`` to the actual number of blocks. If there are no EDID blocks | |
cdb4af0f | 59 | available at all, then the error code ``ENODATA`` is set. |
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60 | |
61 | If blocks have to be retrieved from the sink, then this call will block | |
62 | until they have been read. | |
63 | ||
64 | If ``start_block`` and ``blocks`` are both set to 0 when | |
4e03cb76 | 65 | :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>` is called, then the driver will set ``blocks`` to the |
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66 | total number of available EDID blocks and it will return 0 without |
67 | copying any data. This is an easy way to discover how many EDID blocks | |
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68 | there are. |
69 | ||
70 | .. note:: If there are no EDID blocks available at all, then | |
71 | the driver will set ``blocks`` to 0 and it returns 0. | |
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72 | |
73 | To set the EDID blocks of a receiver the application has to fill in the | |
74 | ``pad``, ``blocks`` and ``edid`` fields, set ``start_block`` to 0 and | |
75 | zero the ``reserved`` array. It is not possible to set part of an EDID, | |
76 | it is always all or nothing. Setting the EDID data is only valid for | |
77 | receivers as it makes no sense for a transmitter. | |
78 | ||
79 | The driver assumes that the full EDID is passed in. If there are more | |
80 | EDID blocks than the hardware can handle then the EDID is not written, | |
cdb4af0f | 81 | but instead the error code ``E2BIG`` is set and ``blocks`` is set to the |
5377d91f | 82 | maximum that the hardware supports. If ``start_block`` is any value |
cdb4af0f | 83 | other than 0 then the error code ``EINVAL`` is set. |
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84 | |
85 | To disable an EDID you set ``blocks`` to 0. Depending on the hardware | |
86 | this will drive the hotplug pin low and/or block the source from reading | |
87 | the EDID data in some way. In any case, the end result is the same: the | |
88 | EDID is no longer available. | |
89 | ||
90 | ||
91 | .. _v4l2-edid: | |
92 | ||
93 | .. flat-table:: struct v4l2_edid | |
94 | :header-rows: 0 | |
95 | :stub-columns: 0 | |
96 | :widths: 1 1 2 | |
97 | ||
98 | ||
99 | - .. row 1 | |
100 | ||
101 | - __u32 | |
102 | ||
103 | - ``pad`` | |
104 | ||
105 | - Pad for which to get/set the EDID blocks. When used with a video | |
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106 | device node the pad represents the input or output index as |
107 | returned by :ref:`VIDIOC_ENUMINPUT` and | |
108 | :ref:`VIDIOC_ENUMOUTPUT` respectively. | |
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109 | |
110 | - .. row 2 | |
111 | ||
112 | - __u32 | |
113 | ||
114 | - ``start_block`` | |
115 | ||
116 | - Read the EDID from starting with this block. Must be 0 when | |
0579e6e3 | 117 | setting the EDID. |
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118 | |
119 | - .. row 3 | |
120 | ||
121 | - __u32 | |
122 | ||
123 | - ``blocks`` | |
124 | ||
125 | - The number of blocks to get or set. Must be less or equal to 256 | |
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126 | (the maximum number of blocks as defined by the standard). When |
127 | you set the EDID and ``blocks`` is 0, then the EDID is disabled or | |
128 | erased. | |
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129 | |
130 | - .. row 4 | |
131 | ||
132 | - __u32 | |
133 | ||
ffbab694 | 134 | - ``reserved``\ \[5\] |
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135 | |
136 | - Reserved for future extensions. Applications and drivers must set | |
0579e6e3 | 137 | the array to zero. |
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138 | |
139 | - .. row 5 | |
140 | ||
141 | - __u8 * | |
142 | ||
143 | - ``edid`` | |
144 | ||
145 | - Pointer to memory that contains the EDID. The minimum size is | |
0579e6e3 | 146 | ``blocks`` * 128. |
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147 | |
148 | ||
15e7d615 | 149 | Return Value |
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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. |