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diff --git a/Documentation/media/uapi/v4l/vidioc-s-hw-freq-seek.rst b/Documentation/media/uapi/v4l/vidioc-s-hw-freq-seek.rst new file mode 100644 index 000000000..5fd332a5b --- /dev/null +++ b/Documentation/media/uapi/v4l/vidioc-s-hw-freq-seek.rst @@ -0,0 +1,179 @@ +.. -*- coding: utf-8; mode: rst -*- + +.. _VIDIOC_S_HW_FREQ_SEEK: + +*************************** +ioctl VIDIOC_S_HW_FREQ_SEEK +*************************** + +Name +==== + +VIDIOC_S_HW_FREQ_SEEK - Perform a hardware frequency seek + + +Synopsis +======== + +.. cpp:function:: int ioctl( int fd, int request, struct v4l2_hw_freq_seek *argp ) + + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`open() <func-open>`. + +``request`` + VIDIOC_S_HW_FREQ_SEEK + +``argp`` + + +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 +:ref:`v4l2_hw_freq_seek <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 +:ref:`v4l2_tuner <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. + + +.. _v4l2-hw-freq-seek: + +.. flat-table:: struct v4l2_hw_freq_seek + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + + - .. row 1 + + - __u32 + + - ``tuner`` + + - The tuner index number. This is the same value as in the struct + :ref:`v4l2_input <v4l2-input>` ``tuner`` field and the struct + :ref:`v4l2_tuner <v4l2-tuner>` ``index`` field. + + - .. row 2 + + - __u32 + + - ``type`` + + - The tuner type. This is the same value as in the struct + :ref:`v4l2_tuner <v4l2-tuner>` ``type`` field. See + :ref:`v4l2-tuner-type` + + - .. row 3 + + - __u32 + + - ``seek_upward`` + + - If non-zero, seek upward from the current frequency, else seek + downward. + + - .. row 4 + + - __u32 + + - ``wrap_around`` + + - If non-zero, wrap around when at the end of the frequency range, + else stop seeking. The struct :ref:`v4l2_tuner <v4l2-tuner>` + ``capability`` field will tell you what the hardware supports. + + - .. row 5 + + - __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. + + - .. row 6 + + - __u32 + + - ``rangelow`` + + - If non-zero, the lowest tunable frequency of the band to search in + units of 62.5 kHz, or if the struct + :ref:`v4l2_tuner <v4l2-tuner>` ``capability`` field has the + ``V4L2_TUNER_CAP_LOW`` flag set, in units of 62.5 Hz or if the + struct :ref:`v4l2_tuner <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. + + - .. row 7 + + - __u32 + + - ``rangehigh`` + + - If non-zero, the highest tunable frequency of the band to search + in units of 62.5 kHz, or if the struct + :ref:`v4l2_tuner <v4l2-tuner>` ``capability`` field has the + ``V4L2_TUNER_CAP_LOW`` flag set, in units of 62.5 Hz or if the + struct :ref:`v4l2_tuner <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. + + - .. row 8 + + - __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. |