int (*vidioc_g_frequency) (struct file *file, void *fh,
struct v4l2_frequency *a);
int (*vidioc_s_frequency) (struct file *file, void *fh,
int (*vidioc_g_frequency) (struct file *file, void *fh,
struct v4l2_frequency *a);
int (*vidioc_s_frequency) (struct file *file, void *fh,