ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY &manvol; VIDIOC_G_FREQUENCY VIDIOC_S_FREQUENCY Get or set tuner or modulator radio frequency int ioctl int fd int request struct v4l2_frequency *argp int ioctl int fd int request const struct v4l2_frequency *argp fd &fd; request VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY argp To get the current tuner or modulator radio frequency applications set the tuner field of a &v4l2-frequency; to the respective tuner or modulator number (only input devices have tuners, only output devices have modulators), zero out the reserved array and call the VIDIOC_G_FREQUENCY ioctl with a pointer to this structure. The driver stores the current frequency in the frequency field. To change the current tuner or modulator radio frequency applications initialize the tuner, type and frequency fields, and the reserved array of a &v4l2-frequency; and call the VIDIOC_S_FREQUENCY ioctl with a pointer to this structure. When the requested frequency is not possible the driver assumes the closest possible value. However VIDIOC_S_FREQUENCY is a write-only ioctl, it does not return the actual new frequency. &cs-str; __u32 tuner The tuner or modulator index number. This is the same value as in the &v4l2-input; tuner field and the &v4l2-tuner; index field, or the &v4l2-output; modulator field and the &v4l2-modulator; index field. &v4l2-tuner-type; type The tuner type. This is the same value as in the &v4l2-tuner; type field. The type must be set to V4L2_TUNER_RADIO for /dev/radioX device nodes, and to V4L2_TUNER_ANALOG_TV for all others. The field is not applicable to modulators, &ie; ignored by drivers. __u32 frequency Tuning frequency in units of 62.5 kHz, or if the &v4l2-tuner; or &v4l2-modulator; capabilities flag V4L2_TUNER_CAP_LOW is set, in units of 62.5 Hz. __u32 reserved[8] Reserved for future extensions. Drivers and applications must set the array to zero. &return-value; EINVAL The tuner index is out of bounds or the value in the type field is wrong.