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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 | ||
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18 | .. c:function:: int ioctl( int fd, VIDIOC_G_EDID, struct v4l2_edid *argp ) |
19 | :name: VIDIOC_G_EDID | |
20 | ||
21 | .. c:function:: int ioctl( int fd, VIDIOC_S_EDID, struct v4l2_edid *argp ) | |
22 | :name: VIDIOC_S_EDID | |
23 | ||
24 | ||
25 | .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_EDID, struct v4l2_edid *argp ) | |
26 | :name: VIDIOC_SUBDEV_G_EDID | |
27 | ||
28 | .. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_EDID, struct v4l2_edid *argp ) | |
29 | :name: VIDIOC_SUBDEV_S_EDID | |
5377d91f | 30 | |
586027ce | 31 | |
15e7d615 | 32 | Arguments |
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33 | ========= |
34 | ||
35 | ``fd`` | |
36 | File descriptor returned by :ref:`open() <func-open>`. | |
37 | ||
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38 | ``argp`` |
39 | ||
40 | ||
15e7d615 | 41 | Description |
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42 | =========== |
43 | ||
44 | These ioctls can be used to get or set an EDID associated with an input | |
45 | from a receiver or an output of a transmitter device. They can be used | |
46 | with subdevice nodes (/dev/v4l-subdevX) or with video nodes | |
47 | (/dev/videoX). | |
48 | ||
49 | When used with video nodes the ``pad`` field represents the input (for | |
50 | video capture devices) or output (for video output devices) index as is | |
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51 | returned by :ref:`VIDIOC_ENUMINPUT` and |
52 | :ref:`VIDIOC_ENUMOUTPUT` respectively. When used | |
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53 | with subdevice nodes the ``pad`` field represents the input or output |
54 | pad of the subdevice. If there is no EDID support for the given ``pad`` | |
cdb4af0f | 55 | value, then the ``EINVAL`` error code will be returned. |
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56 | |
57 | To get the EDID data the application has to fill in the ``pad``, | |
58 | ``start_block``, ``blocks`` and ``edid`` fields, zero the ``reserved`` | |
4e03cb76 | 59 | array and call :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>`. The current EDID from block |
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60 | ``start_block`` and of size ``blocks`` will be placed in the memory |
61 | ``edid`` points to. The ``edid`` pointer must point to memory at least | |
62 | ``blocks`` * 128 bytes large (the size of one block is 128 bytes). | |
63 | ||
64 | If there are fewer blocks than specified, then the driver will set | |
65 | ``blocks`` to the actual number of blocks. If there are no EDID blocks | |
cdb4af0f | 66 | available at all, then the error code ``ENODATA`` is set. |
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67 | |
68 | If blocks have to be retrieved from the sink, then this call will block | |
69 | until they have been read. | |
70 | ||
71 | If ``start_block`` and ``blocks`` are both set to 0 when | |
4e03cb76 | 72 | :ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>` is called, then the driver will set ``blocks`` to the |
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73 | total number of available EDID blocks and it will return 0 without |
74 | copying any data. This is an easy way to discover how many EDID blocks | |
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75 | there are. |
76 | ||
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77 | .. note:: |
78 | ||
79 | If there are no EDID blocks available at all, then | |
706f8a99 | 80 | the driver will set ``blocks`` to 0 and it returns 0. |
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81 | |
82 | To set the EDID blocks of a receiver the application has to fill in the | |
83 | ``pad``, ``blocks`` and ``edid`` fields, set ``start_block`` to 0 and | |
84 | zero the ``reserved`` array. It is not possible to set part of an EDID, | |
85 | it is always all or nothing. Setting the EDID data is only valid for | |
86 | receivers as it makes no sense for a transmitter. | |
87 | ||
88 | The driver assumes that the full EDID is passed in. If there are more | |
89 | EDID blocks than the hardware can handle then the EDID is not written, | |
cdb4af0f | 90 | but instead the error code ``E2BIG`` is set and ``blocks`` is set to the |
5377d91f | 91 | maximum that the hardware supports. If ``start_block`` is any value |
cdb4af0f | 92 | other than 0 then the error code ``EINVAL`` is set. |
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93 | |
94 | To disable an EDID you set ``blocks`` to 0. Depending on the hardware | |
95 | this will drive the hotplug pin low and/or block the source from reading | |
96 | the EDID data in some way. In any case, the end result is the same: the | |
97 | EDID is no longer available. | |
98 | ||
99 | ||
56683d7d | 100 | .. c:type:: v4l2_edid |
5377d91f | 101 | |
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102 | .. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| |
103 | ||
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104 | .. flat-table:: struct v4l2_edid |
105 | :header-rows: 0 | |
106 | :stub-columns: 0 | |
107 | :widths: 1 1 2 | |
108 | ||
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109 | * - __u32 |
110 | - ``pad`` | |
111 | - Pad for which to get/set the EDID blocks. When used with a video | |
112 | device node the pad represents the input or output index as | |
113 | returned by :ref:`VIDIOC_ENUMINPUT` and | |
114 | :ref:`VIDIOC_ENUMOUTPUT` respectively. | |
115 | * - __u32 | |
116 | - ``start_block`` | |
117 | - Read the EDID from starting with this block. Must be 0 when | |
118 | setting the EDID. | |
119 | * - __u32 | |
120 | - ``blocks`` | |
121 | - The number of blocks to get or set. Must be less or equal to 256 | |
122 | (the maximum number of blocks as defined by the standard). When | |
123 | you set the EDID and ``blocks`` is 0, then the EDID is disabled or | |
124 | erased. | |
125 | * - __u32 | |
126 | - ``reserved``\ [5] | |
127 | - Reserved for future extensions. Applications and drivers must set | |
128 | the array to zero. | |
129 | * - __u8 * | |
130 | - ``edid`` | |
131 | - Pointer to memory that contains the EDID. The minimum size is | |
132 | ``blocks`` * 128. | |
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133 | |
134 | ||
15e7d615 | 135 | Return Value |
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136 | ============ |
137 | ||
138 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
139 | appropriately. The generic error codes are described at the | |
140 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
141 | ||
cdb4af0f | 142 | ``ENODATA`` |
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143 | The EDID data is not available. |
144 | ||
cdb4af0f | 145 | ``E2BIG`` |
5377d91f | 146 | The EDID data you provided is more than the hardware can handle. |