8.53. ioctl VIDIOC_S_HW_FREQ_SEEK¶
8.53.1. Name¶
VIDIOC_S_HW_FREQ_SEEK - Perform a hardware frequency seek
8.53.4. 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.
__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
enum 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. |
8.53.5. 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, thewrap_around
value is not supported or one of the values in thetype
,rangelow
orrangehigh
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.