7.54. ioctl VIDIOC_S_HW_FREQ_SEEK

7.54.1. Name

VIDIOC_S_HW_FREQ_SEEK - Perform a hardware frequency seek

7.54.2. Synopsis

VIDIOC_S_HW_FREQ_SEEK

int ioctl(int fd, VIDIOC_S_HW_FREQ_SEEK, struct v4l2_hw_freq_seek *argp)

7.54.3. Arguments

fd

File descriptor returned by open().

argp

Pointer to struct v4l2_hw_freq_seek.

7.54.4. 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 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 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 ioctl 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 ioctl 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.

type v4l2_hw_freq_seek

struct v4l2_hw_freq_seek

__u32	tuner	The tuner index number. This is the same value as in the struct v4l2_input tuner field and the struct v4l2_tuner index field.
__u32	type	The tuner type. This is the same value as in the struct v4l2_tuner type field. See 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 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 v4l2_tuner capability field has the V4L2_TUNER_CAP_LOW flag set, in units of 62.5 Hz or if the struct 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 v4l2_tuner capability field has the V4L2_TUNER_CAP_LOW flag set, in units of 62.5 Hz or if the struct 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.

7.54.5. 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 Generic Error Codes 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.