.. Permission is granted to copy, distribute and/or modify this
.. document under the terms of the GNU Free Documentation License,
.. Version 1.1 or any later version published by the Free Software
.. Foundation, with no Invariant Sections, no Front-Cover Texts
.. and no Back-Cover Texts. A copy of the license is included at
.. Documentation/userspace-api/media/fdl-appendix.rst.
..
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections

.. _VIDIOC_ENUM_DV_TIMINGS:

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

Name
====

VIDIOC_ENUM_DV_TIMINGS - VIDIOC_SUBDEV_ENUM_DV_TIMINGS - Enumerate supported Digital Video timings


Synopsis
========

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

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


Arguments
=========

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

``argp``
    Pointer to struct :c:type:`v4l2_enum_dv_timings`.


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` 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
:c:type:`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::

   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
:c:type:`v4l2_enum_dv_timings` ``pad`` field.
Attempts to enumerate timings on a pad that doesn't support them will
return an ``EINVAL`` error code.


.. c:type:: v4l2_enum_dv_timings

.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|

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

    * - __u32
      - ``index``
      - Number of the DV timings, set by the application.
    * - __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.
    * - __u32
      - ``reserved``\ [2]
      - Reserved for future extensions. Drivers and applications must set
	the array to zero.
    * - struct :c:type:`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 :c:type:`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.
