linux_dsm_epyc7002/Documentation/linux_tv/media/v4l/vidioc-enum-freq-bands.rst
Mauro Carvalho Chehab b7e67f6c1b doc-rst: linux_tv: supress lots of warnings
The c language parser checks if there are duplicated object
definitions. That causes lots of warnings like:
	WARNING: duplicate C object description of ioctl

Let's remove those by telling Sphinx that the language for
those objects are c++. The look of the descriptions will
be close, and the warnings will be gone.

Please notice that we had to keep a few of them as C, as
the c++ parser seems to be broken when it finds an enum.

Yet, this reduced from 219 warnings to 143, with is
a good thing.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2016-07-03 10:05:16 -03:00

199 lines
5.1 KiB
ReStructuredText

.. -*- coding: utf-8; mode: rst -*-
.. _VIDIOC_ENUM_FREQ_BANDS:
****************************
ioctl VIDIOC_ENUM_FREQ_BANDS
****************************
*man VIDIOC_ENUM_FREQ_BANDS(2)*
Enumerate supported frequency bands
Synopsis
========
.. cpp:function:: int ioctl( int fd, int request, struct v4l2_frequency_band *argp )
Arguments
=========
``fd``
File descriptor returned by :ref:`open() <func-open>`.
``request``
VIDIOC_ENUM_FREQ_BANDS
``argp``
Description
===========
Enumerates the frequency bands that a tuner or modulator supports. To do
this applications initialize the ``tuner``, ``type`` and ``index``
fields, and zero out the ``reserved`` array of a struct
:ref:`v4l2_frequency_band <v4l2-frequency-band>` and call the
:ref:`VIDIOC_ENUM_FREQ_BANDS` ioctl with a pointer to this structure.
This ioctl is supported if the ``V4L2_TUNER_CAP_FREQ_BANDS`` capability
of the corresponding tuner/modulator is set.
.. _v4l2-frequency-band:
.. flat-table:: struct v4l2_frequency_band
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2 1 1
- .. row 1
- __u32
- ``tuner``
- The tuner or modulator index number. This is the same value as in
the struct :ref:`v4l2_input <v4l2-input>` ``tuner`` field and
the struct :ref:`v4l2_tuner <v4l2-tuner>` ``index`` field, or
the struct :ref:`v4l2_output <v4l2-output>` ``modulator`` field
and the struct :ref:`v4l2_modulator <v4l2-modulator>` ``index``
field.
- .. row 2
- __u32
- ``type``
- The tuner type. This is the same value as in the struct
:ref:`v4l2_tuner <v4l2-tuner>` ``type`` field. The type must be
set to ``V4L2_TUNER_RADIO`` for ``/dev/radioX`` device nodes, and
to ``V4L2_TUNER_ANALOG_TV`` for all others. Set this field to
``V4L2_TUNER_RADIO`` for modulators (currently only radio
modulators are supported). See :ref:`v4l2-tuner-type`
- .. row 3
- __u32
- ``index``
- Identifies the frequency band, set by the application.
- .. row 4
- __u32
- ``capability``
- :cspan:`2` The tuner/modulator capability flags for this
frequency band, see :ref:`tuner-capability`. The
``V4L2_TUNER_CAP_LOW`` or ``V4L2_TUNER_CAP_1HZ`` capability must
be the same for all frequency bands of the selected
tuner/modulator. So either all bands have that capability set, or
none of them have that capability.
- .. row 5
- __u32
- ``rangelow``
- :cspan:`2` The lowest tunable frequency in units of 62.5 kHz, or
if the ``capability`` flag ``V4L2_TUNER_CAP_LOW`` is set, in units
of 62.5 Hz, for this frequency band. A 1 Hz unit is used when the
``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is set.
- .. row 6
- __u32
- ``rangehigh``
- :cspan:`2` The highest tunable frequency in units of 62.5 kHz,
or if the ``capability`` flag ``V4L2_TUNER_CAP_LOW`` is set, in
units of 62.5 Hz, for this frequency band. A 1 Hz unit is used
when the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is set.
- .. row 7
- __u32
- ``modulation``
- :cspan:`2` The supported modulation systems of this frequency
band. See :ref:`band-modulation`. Note that currently only one
modulation system per frequency band is supported. More work will
need to be done if multiple modulation systems are possible.
Contact the linux-media mailing list
(`https://linuxtv.org/lists.php <https://linuxtv.org/lists.php>`__)
if you need that functionality.
- .. row 8
- __u32
- ``reserved``\ [9]
- Reserved for future extensions. Applications and drivers must set
the array to zero.
.. _band-modulation:
.. flat-table:: Band Modulation Systems
:header-rows: 0
:stub-columns: 0
:widths: 3 1 4
- .. row 1
- ``V4L2_BAND_MODULATION_VSB``
- 0x02
- Vestigial Sideband modulation, used for analog TV.
- .. row 2
- ``V4L2_BAND_MODULATION_FM``
- 0x04
- Frequency Modulation, commonly used for analog radio.
- .. row 3
- ``V4L2_BAND_MODULATION_AM``
- 0x08
- Amplitude Modulation, commonly used for analog radio.
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 ``tuner`` or ``index`` is out of bounds or the ``type`` field is
wrong.
.. ------------------------------------------------------------------------------
.. This file was automatically converted from DocBook-XML with the dbxml
.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
.. from the linux kernel, refer to:
..
.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
.. ------------------------------------------------------------------------------