usb_audio_feature_unit
uaudio_mixer_feature_get_bmaControls(const struct usb_audio_feature_unit *d,
const struct usb_audio_feature_unit *d = iot[id].u.fu_v1;
const struct usb_audio_feature_unit *fu;
const struct usb_audio_feature_unit *fu_v1;
const struct usb_audio_feature_unit *, uint8_t);