1.. -*- coding: utf-8; mode: rst -*-
2
3.. _VIDIOC_ENUM_DV_TIMINGS:
4
5***********************************************************
6ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS
7***********************************************************
8
9Name
10====
11
12VIDIOC_ENUM_DV_TIMINGS - VIDIOC_SUBDEV_ENUM_DV_TIMINGS - Enumerate supported Digital Video timings
13
14
15Synopsis
16========
17
18.. c:function:: int ioctl( int fd, VIDIOC_ENUM_DV_TIMINGS, struct v4l2_enum_dv_timings *argp )
19    :name: VIDIOC_ENUM_DV_TIMINGS
20
21.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_ENUM_DV_TIMINGS, struct v4l2_enum_dv_timings *argp )
22    :name: VIDIOC_SUBDEV_ENUM_DV_TIMINGS
23
24
25Arguments
26=========
27
28``fd``
29    File descriptor returned by :ref:`open() <func-open>`.
30
31``argp``
32    Pointer to struct :c:type:`v4l2_enum_dv_timings`.
33
34
35Description
36===========
37
38While some DV receivers or transmitters support a wide range of timings,
39others support only a limited number of timings. With this ioctl
40applications can enumerate a list of known supported timings. Call
41:ref:`VIDIOC_DV_TIMINGS_CAP` to check if it
42also supports other standards or even custom timings that are not in
43this list.
44
45To query the available timings, applications initialize the ``index``
46field, set the ``pad`` field to 0, zero the reserved array of struct
47:c:type:`v4l2_enum_dv_timings` and call the
48``VIDIOC_ENUM_DV_TIMINGS`` ioctl on a video node with a pointer to this
49structure. Drivers fill the rest of the structure or return an ``EINVAL``
50error code when the index is out of bounds. To enumerate all supported
51DV timings, applications shall begin at index zero, incrementing by one
52until the driver returns ``EINVAL``.
53
54.. note::
55
56   Drivers may enumerate a different set of DV timings after
57   switching the video input or output.
58
59When implemented by the driver DV timings of subdevices can be queried
60by calling the ``VIDIOC_SUBDEV_ENUM_DV_TIMINGS`` ioctl directly on a
61subdevice node. The DV timings are specific to inputs (for DV receivers)
62or outputs (for DV transmitters), applications must specify the desired
63pad number in the struct
64:c:type:`v4l2_enum_dv_timings` ``pad`` field.
65Attempts to enumerate timings on a pad that doesn't support them will
66return an ``EINVAL`` error code.
67
68
69.. c:type:: v4l2_enum_dv_timings
70
71.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
72
73.. flat-table:: struct v4l2_enum_dv_timings
74    :header-rows:  0
75    :stub-columns: 0
76    :widths:       1 1 2
77
78    * - __u32
79      - ``index``
80      - Number of the DV timings, set by the application.
81    * - __u32
82      - ``pad``
83      - Pad number as reported by the media controller API. This field is
84	only used when operating on a subdevice node. When operating on a
85	video node applications must set this field to zero.
86    * - __u32
87      - ``reserved``\ [2]
88      - Reserved for future extensions. Drivers and applications must set
89	the array to zero.
90    * - struct :c:type:`v4l2_dv_timings`
91      - ``timings``
92      - The timings.
93
94
95Return Value
96============
97
98On success 0 is returned, on error -1 and the ``errno`` variable is set
99appropriately. The generic error codes are described at the
100:ref:`Generic Error Codes <gen-errors>` chapter.
101
102EINVAL
103    The struct :c:type:`v4l2_enum_dv_timings`
104    ``index`` is out of bounds or the ``pad`` number is invalid.
105
106ENODATA
107    Digital video presets are not supported for this input or output.
108