1 .. -*- coding: utf-8; mode: rst -*-
3 .. _VIDIOC_G_FREQUENCY:
5 ********************************************
6 ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY
7 ********************************************
9 *man VIDIOC_G_FREQUENCY(2)*
12 Get or set tuner or modulator radio frequency
18 .. c:function:: int ioctl( int fd, int request, struct v4l2_frequency *argp )
20 .. c:function:: int ioctl( int fd, int request, const struct v4l2_frequency *argp )
26 File descriptor returned by :ref:`open() <func-open>`.
29 VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY
37 To get the current tuner or modulator radio frequency applications set
38 the ``tuner`` field of a struct
39 :ref:`v4l2_frequency <v4l2-frequency>` to the respective tuner or
40 modulator number (only input devices have tuners, only output devices
41 have modulators), zero out the ``reserved`` array and call the
42 :ref:`VIDIOC_G_FREQUENCY` ioctl with a pointer to this structure. The
43 driver stores the current frequency in the ``frequency`` field.
45 To change the current tuner or modulator radio frequency applications
46 initialize the ``tuner``, ``type`` and ``frequency`` fields, and the
47 ``reserved`` array of a struct :ref:`v4l2_frequency <v4l2-frequency>`
48 and call the :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>` ioctl with a pointer to this
49 structure. When the requested frequency is not possible the driver
50 assumes the closest possible value. However :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>` is a
51 write-only ioctl, it does not return the actual new frequency.
56 .. flat-table:: struct v4l2_frequency
68 - The tuner or modulator index number. This is the same value as in
69 the struct :ref:`v4l2_input <v4l2-input>` ``tuner`` field and
70 the struct :ref:`v4l2_tuner <v4l2-tuner>` ``index`` field, or
71 the struct :ref:`v4l2_output <v4l2-output>` ``modulator`` field
72 and the struct :ref:`v4l2_modulator <v4l2-modulator>` ``index``
81 - The tuner type. This is the same value as in the struct
82 :ref:`v4l2_tuner <v4l2-tuner>` ``type`` field. The type must be
83 set to ``V4L2_TUNER_RADIO`` for ``/dev/radioX`` device nodes, and
84 to ``V4L2_TUNER_ANALOG_TV`` for all others. Set this field to
85 ``V4L2_TUNER_RADIO`` for modulators (currently only radio
86 modulators are supported). See :ref:`v4l2-tuner-type`
94 - Tuning frequency in units of 62.5 kHz, or if the struct
95 :ref:`v4l2_tuner <v4l2-tuner>` or struct
96 :ref:`v4l2_modulator <v4l2-modulator>` ``capability`` flag
97 ``V4L2_TUNER_CAP_LOW`` is set, in units of 62.5 Hz. A 1 Hz unit is
98 used when the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is set.
106 - Reserved for future extensions. Drivers and applications must set
114 On success 0 is returned, on error -1 and the ``errno`` variable is set
115 appropriately. The generic error codes are described at the
116 :ref:`Generic Error Codes <gen-errors>` chapter.
119 The ``tuner`` index is out of bounds or the value in the ``type``
123 A hardware seek is in progress.
126 .. ------------------------------------------------------------------------------
127 .. This file was automatically converted from DocBook-XML with the dbxml
128 .. library (https://github.com/return42/sphkerneldoc). The origin XML comes
129 .. from the linux kernel, refer to:
131 .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
132 .. ------------------------------------------------------------------------------