media: Documentation/media/uapi: more readable unions

[linux-block.git] / Documentation / media / uapi / v4l / vidioc-dv-timings-cap.rst

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.. 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/media/uapi/fdl-appendix.rst.
..
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections

.. _VIDIOC_DV_TIMINGS_CAP:

*********************************************************
ioctl VIDIOC_DV_TIMINGS_CAP, VIDIOC_SUBDEV_DV_TIMINGS_CAP
*********************************************************

Name
====

VIDIOC_DV_TIMINGS_CAP - VIDIOC_SUBDEV_DV_TIMINGS_CAP - The capabilities of the Digital Video receiver/transmitter


Synopsis
========

.. c:function:: int ioctl( int fd, VIDIOC_DV_TIMINGS_CAP, struct v4l2_dv_timings_cap *argp )
    :name: VIDIOC_DV_TIMINGS_CAP

.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_DV_TIMINGS_CAP, struct v4l2_dv_timings_cap *argp )
    :name: VIDIOC_SUBDEV_DV_TIMINGS_CAP


Arguments
=========

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

``argp``
    Pointer to struct :c:type:`v4l2_dv_timings_cap`.


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

To query the capabilities of the DV receiver/transmitter applications
initialize the ``pad`` field to 0, zero the reserved array of struct
:c:type:`v4l2_dv_timings_cap` and call the
``VIDIOC_DV_TIMINGS_CAP`` ioctl on a video node and the driver will fill
in the structure.

.. note::

   Drivers may return different values after
   switching the video input or output.

When implemented by the driver DV capabilities of subdevices can be
queried by calling the ``VIDIOC_SUBDEV_DV_TIMINGS_CAP`` ioctl directly
on a subdevice node. The capabilities 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_dv_timings_cap` ``pad`` field and
zero the ``reserved`` array. Attempts to query capabilities on a pad
that doesn't support them will return an ``EINVAL`` error code.


.. tabularcolumns:: |p{1.2cm}|p{3.0cm}|p{13.3cm}|

.. c:type:: v4l2_bt_timings_cap

.. flat-table:: struct v4l2_bt_timings_cap
    :header-rows:  0
    :stub-columns: 0
    :widths:       1 1 2

    * - __u32
      - ``min_width``
      - Minimum width of the active video in pixels.
    * - __u32
      - ``max_width``
      - Maximum width of the active video in pixels.
    * - __u32
      - ``min_height``
      - Minimum height of the active video in lines.
    * - __u32
      - ``max_height``
      - Maximum height of the active video in lines.
    * - __u64
      - ``min_pixelclock``
      - Minimum pixelclock frequency in Hz.
    * - __u64
      - ``max_pixelclock``
      - Maximum pixelclock frequency in Hz.
    * - __u32
      - ``standards``
      - The video standard(s) supported by the hardware. See
	:ref:`dv-bt-standards` for a list of standards.
    * - __u32
      - ``capabilities``
      - Several flags giving more information about the capabilities. See
	:ref:`dv-bt-cap-capabilities` for a description of the flags.
    * - __u32
      - ``reserved``\ [16]
      - Reserved for future extensions.
	Drivers must set the array to zero.



.. tabularcolumns:: |p{1.0cm}|p{4.0cm}|p{3.5cm}|p{9.2cm}|

.. c:type:: v4l2_dv_timings_cap

.. flat-table:: struct v4l2_dv_timings_cap
    :header-rows:  0
    :stub-columns: 0
    :widths:       1 1 2

    * - __u32
      - ``type``
      - Type of DV timings as listed in :ref:`dv-timing-types`.
    * - __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.
    * - union {
      - (anonymous)
    * - struct :c:type:`v4l2_bt_timings_cap`
      - ``bt``
      - BT.656/1120 timings capabilities of the hardware.
    * - __u32
      - ``raw_data``\ [32]
    * - }
      -

.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|

.. _dv-bt-cap-capabilities:

.. flat-table:: DV BT Timing capabilities
    :header-rows:  0
    :stub-columns: 0

    * - Flag
      - Description
    * -
      -
    * - ``V4L2_DV_BT_CAP_INTERLACED``
      - Interlaced formats are supported.
    * - ``V4L2_DV_BT_CAP_PROGRESSIVE``
      - Progressive formats are supported.
    * - ``V4L2_DV_BT_CAP_REDUCED_BLANKING``
      - CVT/GTF specific: the timings can make use of reduced blanking
	(CVT) or the 'Secondary GTF' curve (GTF).
    * - ``V4L2_DV_BT_CAP_CUSTOM``
      - Can support non-standard timings, i.e. timings not belonging to
	the standards set in the ``standards`` field.


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.