1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _VIDIOC_G_FREQUENCY: 5 6******************************************** 7ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY 8******************************************** 9 10Name 11==== 12 13VIDIOC_G_FREQUENCY - VIDIOC_S_FREQUENCY - Get or set tuner or modulator radio frequency 14 15Synopsis 16======== 17 18.. c:macro:: VIDIOC_G_FREQUENCY 19 20``int ioctl(int fd, VIDIOC_G_FREQUENCY, struct v4l2_frequency *argp)`` 21 22.. c:macro:: VIDIOC_S_FREQUENCY 23 24``int ioctl(int fd, VIDIOC_S_FREQUENCY, const struct v4l2_frequency *argp)`` 25 26Arguments 27========= 28 29``fd`` 30 File descriptor returned by :c:func:`open()`. 31 32``argp`` 33 Pointer to struct :c:type:`v4l2_frequency`. 34 35Description 36=========== 37 38To get the current tuner or modulator radio frequency applications set 39the ``tuner`` field of a struct 40:c:type:`v4l2_frequency` to the respective tuner or 41modulator number (only input devices have tuners, only output devices 42have modulators), zero out the ``reserved`` array and call the 43:ref:`VIDIOC_G_FREQUENCY <VIDIOC_G_FREQUENCY>` ioctl with a pointer to this structure. The 44driver stores the current frequency in the ``frequency`` field. 45 46To change the current tuner or modulator radio frequency applications 47initialize the ``tuner``, ``type`` and ``frequency`` fields, and the 48``reserved`` array of a struct :c:type:`v4l2_frequency` 49and call the :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>` ioctl with a pointer to this 50structure. When the requested frequency is not possible the driver 51assumes the closest possible value. However :ref:`VIDIOC_S_FREQUENCY <VIDIOC_G_FREQUENCY>` is a 52write-only ioctl, it does not return the actual new frequency. 53 54.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| 55 56.. c:type:: v4l2_frequency 57 58.. flat-table:: struct v4l2_frequency 59 :header-rows: 0 60 :stub-columns: 0 61 :widths: 1 1 2 62 63 * - __u32 64 - ``tuner`` 65 - The tuner or modulator index number. This is the same value as in 66 the struct :c:type:`v4l2_input` ``tuner`` field and 67 the struct :c:type:`v4l2_tuner` ``index`` field, or 68 the struct :c:type:`v4l2_output` ``modulator`` field 69 and the struct :c:type:`v4l2_modulator` ``index`` 70 field. 71 * - __u32 72 - ``type`` 73 - The tuner type. This is the same value as in the struct 74 :c:type:`v4l2_tuner` ``type`` field. The type must be 75 set to ``V4L2_TUNER_RADIO`` for ``/dev/radioX`` device nodes, and 76 to ``V4L2_TUNER_ANALOG_TV`` for all others. Set this field to 77 ``V4L2_TUNER_RADIO`` for modulators (currently only radio 78 modulators are supported). See :c:type:`v4l2_tuner_type` 79 * - __u32 80 - ``frequency`` 81 - Tuning frequency in units of 62.5 kHz, or if the struct 82 :c:type:`v4l2_tuner` or struct 83 :c:type:`v4l2_modulator` ``capability`` flag 84 ``V4L2_TUNER_CAP_LOW`` is set, in units of 62.5 Hz. A 1 Hz unit is 85 used when the ``capability`` flag ``V4L2_TUNER_CAP_1HZ`` is set. 86 * - __u32 87 - ``reserved``\ [8] 88 - Reserved for future extensions. Drivers and applications must set 89 the array to zero. 90 91Return Value 92============ 93 94On success 0 is returned, on error -1 and the ``errno`` variable is set 95appropriately. The generic error codes are described at the 96:ref:`Generic Error Codes <gen-errors>` chapter. 97 98EINVAL 99 The ``tuner`` index is out of bounds or the value in the ``type`` 100 field is wrong. 101 102EBUSY 103 A hardware seek is in progress. 104