usb_audio_control
static int generic_set_cmd(struct usb_audio_control *con, u8 cmd, int value);
static int generic_get_cmd(struct usb_audio_control *con, u8 cmd);
struct usb_audio_control *set_con;
struct usb_audio_control *con = audio->set_con;
struct usb_audio_control *con;
struct usb_audio_control *con;
static int generic_set_cmd(struct usb_audio_control *con, u8 cmd, int value)
static int generic_get_cmd(struct usb_audio_control *con, u8 cmd)
static struct usb_audio_control mute_control = {
static struct usb_audio_control volume_control = {
int (*set)(struct usb_audio_control *con, u8 cmd, int value);
int (*get)(struct usb_audio_control *con, u8 cmd);