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

.. -*- coding: utf-8; mode: rst -*-

.. _vidioc-enum-dv-timings:

***********************************************************
ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS
***********************************************************

*man VIDIOC_ENUM_DV_TIMINGS(2)*

VIDIOC_SUBDEV_ENUM_DV_TIMINGS
Enumerate supported Digital Video timings


Synopsis
========

.. c:function:: int ioctl( int fd, int request, struct v4l2_enum_dv_timings *argp )

Arguments
=========

``fd``
    File descriptor returned by :ref:`open() <func-open>`.

``request``
    VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS

``argp``


Description
===========

While some DV receivers or transmitters support a wide range of timings,
others support only a limited number of timings. With this ioctl
applications can enumerate a list of known supported timings. Call
:ref:`VIDIOC_DV_TIMINGS_CAP <vidioc-dv-timings-cap>` to check if it
also supports other standards or even custom timings that are not in
this list.

To query the available timings, applications initialize the ``index``
field, set the ``pad`` field to 0, zero the reserved array of struct
:ref:`v4l2_enum_dv_timings <v4l2-enum-dv-timings>` and call the
``VIDIOC_ENUM_DV_TIMINGS`` ioctl on a video node with a pointer to this
structure. Drivers fill the rest of the structure or return an EINVAL
error code when the index is out of bounds. To enumerate all supported
DV timings, applications shall begin at index zero, incrementing by one
until the driver returns EINVAL. Note that drivers may enumerate a
different set of DV timings after switching the video input or output.

When implemented by the driver DV timings of subdevices can be queried
by calling the ``VIDIOC_SUBDEV_ENUM_DV_TIMINGS`` ioctl directly on a
subdevice node. The DV timings are specific to inputs (for DV receivers)
or outputs (for DV transmitters), applications must specify the desired
pad number in the struct
:ref:`v4l2_enum_dv_timings <v4l2-enum-dv-timings>` ``pad`` field.
Attempts to enumerate timings on a pad that doesn't support them will
return an EINVAL error code.


.. _v4l2-enum-dv-timings:

.. flat-table:: struct v4l2_enum_dv_timings
    :header-rows:  0
    :stub-columns: 0
    :widths:       1 1 2


    -  .. row 1

       -  __u32

       -  ``index``

       -  Number of the DV timings, set by the application.

    -  .. row 2

       -  __u32

       -  ``pad``

       -  Pad number as reported by the media controller API. This field is
          only used when operating on a subdevice node. When operating on a
          video node applications must set this field to zero.

    -  .. row 3

       -  __u32

       -  ``reserved``\ [2]

       -  Reserved for future extensions. Drivers and applications must set
          the array to zero.

    -  .. row 4

       -  struct :ref:`v4l2_dv_timings <v4l2-dv-timings>`

       -  ``timings``

       -  The timings.



Return Value
============

On success 0 is returned, on error -1 and the ``errno`` variable is set
appropriately. The generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.

EINVAL
    The struct :ref:`v4l2_enum_dv_timings <v4l2-enum-dv-timings>`
    ``index`` is out of bounds or the ``pad`` number is invalid.

ENODATA
    Digital video presets are not supported for this input or output.


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.. This file was automatically converted from DocBook-XML with the dbxml
.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
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.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
.. ------------------------------------------------------------------------------