Documentation/linux_tv/media/v4l/vidioc-enum-dv-timings.rst

   1 .. -*- coding: utf-8; mode: rst -*-
   2
   3 .. _VIDIOC_ENUM_DV_TIMINGS:
   4
   5 ***********************************************************
   6 ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS
   7 ***********************************************************
   8
   9 *man VIDIOC_ENUM_DV_TIMINGS(2)*
  10
  11 VIDIOC_SUBDEV_ENUM_DV_TIMINGS
  12 Enumerate supported Digital Video timings
  13
  14
  15 Synopsis
  16 ========
  17
  18 .. c:function:: int ioctl( int fd, int request, struct v4l2_enum_dv_timings *argp )
  19
  20 Arguments
  21 =========
  22
  23 ``fd``
  24     File descriptor returned by :ref:`open() <func-open>`.
  25
  26 ``request``
  27     VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS
  28
  29 ``argp``
  30
  31
  32 Description
  33 ===========
  34
  35 While some DV receivers or transmitters support a wide range of timings,
  36 others support only a limited number of timings. With this ioctl
  37 applications can enumerate a list of known supported timings. Call
  38 :ref:`VIDIOC_DV_TIMINGS_CAP <VIDIOC_DV_TIMINGS_CAP>` to check if it
  39 also supports other standards or even custom timings that are not in
  40 this list.
  41
  42 To query the available timings, applications initialize the ``index``
  43 field, set the ``pad`` field to 0, zero the reserved array of struct
  44 :ref:`v4l2_enum_dv_timings <v4l2-enum-dv-timings>` and call the
  45 ``VIDIOC_ENUM_DV_TIMINGS`` ioctl on a video node with a pointer to this
  46 structure. Drivers fill the rest of the structure or return an EINVAL
  47 error code when the index is out of bounds. To enumerate all supported
  48 DV timings, applications shall begin at index zero, incrementing by one
  49 until the driver returns EINVAL. Note that drivers may enumerate a
  50 different set of DV timings after switching the video input or output.
  51
  52 When implemented by the driver DV timings of subdevices can be queried
  53 by calling the ``VIDIOC_SUBDEV_ENUM_DV_TIMINGS`` ioctl directly on a
  54 subdevice node. The DV timings are specific to inputs (for DV receivers)
  55 or outputs (for DV transmitters), applications must specify the desired
  56 pad number in the struct
  57 :ref:`v4l2_enum_dv_timings <v4l2-enum-dv-timings>` ``pad`` field.
  58 Attempts to enumerate timings on a pad that doesn't support them will
  59 return an EINVAL error code.
  60
  61
  62 .. _v4l2-enum-dv-timings:
  63
  64 .. flat-table:: struct v4l2_enum_dv_timings
  65     :header-rows:  0
  66     :stub-columns: 0
  67     :widths:       1 1 2
  68
  69
  70     -  .. row 1
  71
  72        -  __u32
  73
  74        -  ``index``
  75
  76        -  Number of the DV timings, set by the application.
  77
  78     -  .. row 2
  79
  80        -  __u32
  81
  82        -  ``pad``
  83
  84        -  Pad number as reported by the media controller API. This field is
  85           only used when operating on a subdevice node. When operating on a
  86           video node applications must set this field to zero.
  87
  88     -  .. row 3
  89
  90        -  __u32
  91
  92        -  ``reserved``\ [2]
  93
  94        -  Reserved for future extensions. Drivers and applications must set
  95           the array to zero.
  96
  97     -  .. row 4
  98
  99        -  struct :ref:`v4l2_dv_timings <v4l2-dv-timings>`
 100
 101        -  ``timings``
 102
 103        -  The timings.
 104
 105
 106
 107 Return Value
 108 ============
 109
 110 On success 0 is returned, on error -1 and the ``errno`` variable is set
 111 appropriately. The generic error codes are described at the
 112 :ref:`Generic Error Codes <gen-errors>` chapter.
 113
 114 EINVAL
 115     The struct :ref:`v4l2_enum_dv_timings <v4l2-enum-dv-timings>`
 116     ``index`` is out of bounds or the ``pad`` number is invalid.
 117
 118 ENODATA
 119     Digital video presets are not supported for this input or output.
 120
 121
 122 .. ------------------------------------------------------------------------------
 123 .. This file was automatically converted from DocBook-XML with the dbxml
 124 .. library (https://github.com/return42/sphkerneldoc). The origin XML comes
 125 .. from the linux kernel, refer to:
 126 ..
 127 .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
 128 .. ------------------------------------------------------------------------------