snd_usb_get_cur_mix_value
err = snd_usb_get_cur_mix_value(cval, ch, idx, &val);
err = snd_usb_get_cur_mix_value(cval, c + 1, cnt, &val);
err = snd_usb_get_cur_mix_value(cval, 0, 0, &val);
err = snd_usb_get_cur_mix_value(cval, c + 1, cnt, &oval);
err = snd_usb_get_cur_mix_value(cval, 0, 0, &oval);
err = snd_usb_get_cur_mix_value(cval, 0, 0, &val);
int snd_usb_get_cur_mix_value(struct usb_mixer_elem_info *cval,
err = snd_usb_get_cur_mix_value(elem, i, i, &val);
err = snd_usb_get_cur_mix_value(elem, i, i, &oval);
err = snd_usb_get_cur_mix_value(elem, i, i, &val);
err = snd_usb_get_cur_mix_value(elem, i, i, &oval);
err = snd_usb_get_cur_mix_value(elem, 0, 0, &val);
err = snd_usb_get_cur_mix_value(elem, 0, 0, &oval);