Documentation/userspace-api/media/v4l/vidioc-enum-freq-bands.rst

Source file repositories/reference/linux-study-clean/Documentation/userspace-api/media/v4l/vidioc-enum-freq-bands.rst

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Linux kernel
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Documentation/userspace-api/media/v4l/vidioc-enum-freq-bands.rst
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.rst
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Support Tooling And Documentation
Bucket
Documentation
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Support Tooling And Documentation: documentation
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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Annotated Snippet

.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. c:namespace:: V4L

.. _VIDIOC_ENUM_FREQ_BANDS:

****************************
ioctl VIDIOC_ENUM_FREQ_BANDS
****************************

Name
====

VIDIOC_ENUM_FREQ_BANDS - Enumerate supported frequency bands

Synopsis
========

.. c:macro:: VIDIOC_ENUM_FREQ_BANDS

``int ioctl(int fd, VIDIOC_ENUM_FREQ_BANDS, struct v4l2_frequency_band *argp)``

Arguments
=========

``fd``
    File descriptor returned by :c:func:`open()`.

``argp``
    Pointer to struct :c:type:`v4l2_frequency_band`.

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
:c:type:`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.

.. tabularcolumns:: |p{2.9cm}|p{2.9cm}|p{5.8cm}|p{2.9cm}|p{2.4cm}|

.. c:type:: v4l2_frequency_band

.. flat-table:: struct v4l2_frequency_band
    :header-rows:  0
    :stub-columns: 0
    :widths:       1 1 2 1 1

    * - __u32
      - ``tuner``
      - The tuner or modulator index number. This is the same value as in
	the struct :c:type:`v4l2_input` ``tuner`` field and
	the struct :c:type:`v4l2_tuner` ``index`` field, or
	the struct :c:type:`v4l2_output` ``modulator`` field
	and the struct :c:type:`v4l2_modulator` ``index``
	field.
    * - __u32
      - ``type``
      - The tuner type. This is the same value as in the struct
	:c:type:`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 :c:type:`v4l2_tuner_type`
    * - __u32
      - ``index``
      - Identifies the frequency band, set by the application.

Annotation

Implementation Notes