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| -rw-r--r-- | Documentation/userspace-api/media/v4l/vidioc-s-hw-freq-seek.rst | 137 |
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diff --git a/Documentation/userspace-api/media/v4l/vidioc-s-hw-freq-seek.rst b/Documentation/userspace-api/media/v4l/vidioc-s-hw-freq-seek.rst new file mode 100644 index 000000000..ed10f3805 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/vidioc-s-hw-freq-seek.rst @@ -0,0 +1,137 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later +.. c:namespace:: V4L + +.. _VIDIOC_S_HW_FREQ_SEEK: + +*************************** +ioctl VIDIOC_S_HW_FREQ_SEEK +*************************** + +Name +==== + +VIDIOC_S_HW_FREQ_SEEK - Perform a hardware frequency seek + +Synopsis +======== + +.. c:macro:: VIDIOC_S_HW_FREQ_SEEK + +``int ioctl(int fd, VIDIOC_S_HW_FREQ_SEEK, struct v4l2_hw_freq_seek *argp)`` + +Arguments +========= + +``fd`` + File descriptor returned by :c:func:`open()`. + +``argp`` + Pointer to struct :c:type:`v4l2_hw_freq_seek`. + +Description +=========== + +Start a hardware frequency seek from the current frequency. To do this +applications initialize the ``tuner``, ``type``, ``seek_upward``, +``wrap_around``, ``spacing``, ``rangelow`` and ``rangehigh`` fields, and +zero out the ``reserved`` array of a struct +:c:type:`v4l2_hw_freq_seek` and call the +``VIDIOC_S_HW_FREQ_SEEK`` ioctl with a pointer to this structure. + +The ``rangelow`` and ``rangehigh`` fields can be set to a non-zero value +to tell the driver to search a specific band. If the struct +:c:type:`v4l2_tuner` ``capability`` field has the +``V4L2_TUNER_CAP_HWSEEK_PROG_LIM`` flag set, these values must fall +within one of the bands returned by +:ref:`VIDIOC_ENUM_FREQ_BANDS`. If the +``V4L2_TUNER_CAP_HWSEEK_PROG_LIM`` flag is not set, then these values +must exactly match those of one of the bands returned by +:ref:`VIDIOC_ENUM_FREQ_BANDS`. If the +current frequency of the tuner does not fall within the selected band it +will be clamped to fit in the band before the seek is started. + +If an error is returned, then the original frequency will be restored. + +This ioctl is supported if the ``V4L2_CAP_HW_FREQ_SEEK`` capability is +set. + +If this ioctl is called from a non-blocking filehandle, then ``EAGAIN`` +error code is returned and no seek takes place. + +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| + +.. c:type:: v4l2_hw_freq_seek + +.. flat-table:: struct v4l2_hw_freq_seek + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + * - __u32 + - ``tuner`` + - The tuner 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. + * - __u32 + - ``type`` + - The tuner type. This is the same value as in the struct + :c:type:`v4l2_tuner` ``type`` field. See + :c:type:`v4l2_tuner_type` + * - __u32 + - ``seek_upward`` + - If non-zero, seek upward from the current frequency, else seek + downward. + * - __u32 + - ``wrap_around`` + - If non-zero, wrap around when at the end of the frequency range, + else stop seeking. The struct :c:type:`v4l2_tuner` + ``capability`` field will tell you what the hardware supports. + * - __u32 + - ``spacing`` + - If non-zero, defines the hardware seek resolution in Hz. The + driver selects the nearest value that is supported by the device. + If spacing is zero a reasonable default value is used. + * - __u32 + - ``rangelow`` + - If non-zero, the lowest tunable frequency of the band to search in + units of 62.5 kHz, or if the struct + :c:type:`v4l2_tuner` ``capability`` field has the + ``V4L2_TUNER_CAP_LOW`` flag set, in units of 62.5 Hz or if the + struct :c:type:`v4l2_tuner` ``capability`` field has + the ``V4L2_TUNER_CAP_1HZ`` flag set, in units of 1 Hz. If + ``rangelow`` is zero a reasonable default value is used. + * - __u32 + - ``rangehigh`` + - If non-zero, the highest tunable frequency of the band to search + in units of 62.5 kHz, or if the struct + :c:type:`v4l2_tuner` ``capability`` field has the + ``V4L2_TUNER_CAP_LOW`` flag set, in units of 62.5 Hz or if the + struct :c:type:`v4l2_tuner` ``capability`` field has + the ``V4L2_TUNER_CAP_1HZ`` flag set, in units of 1 Hz. If + ``rangehigh`` is zero a reasonable default value is used. + * - __u32 + - ``reserved``\ [5] + - Reserved for future extensions. Applications must set the array to + zero. + +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`` index is out of bounds, the ``wrap_around`` value is + not supported or one of the values in the ``type``, ``rangelow`` or + ``rangehigh`` fields is wrong. + +EAGAIN + Attempted to call ``VIDIOC_S_HW_FREQ_SEEK`` with the filehandle in + non-blocking mode. + +ENODATA + The hardware seek found no channels. + +EBUSY + Another hardware seek is already in progress. |