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+.. 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.
+ * - __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.
+ * - __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.
+ * - __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.
+ * - __u32
+ - ``modulation``
+ - :cspan:`2` The supported modulation systems of this frequency
+ band. See :ref:`band-modulation`.
+
+ .. note::
+
+ 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 such functionality.
+ * - __u32
+ - ``reserved``\ [9]
+ - Reserved for future extensions.
+
+ Applications and drivers must set the array to zero.
+
+
+.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}|
+
+.. _band-modulation:
+
+.. flat-table:: Band Modulation Systems
+ :header-rows: 0
+ :stub-columns: 0
+ :widths: 3 1 4
+
+ * - ``V4L2_BAND_MODULATION_VSB``
+ - 0x02
+ - Vestigial Sideband modulation, used for analog TV.
+ * - ``V4L2_BAND_MODULATION_FM``
+ - 0x04
+ - Frequency Modulation, commonly used for analog radio.
+ * - ``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.