snd_usb_create_mixer 3640 sound/usb/usbaudio.c snd_usb_create_mixer(chip, ifnum, ignore_ctl_error) < 0) { snd_usb_create_mixer 226 sound/usb/usbaudio.h int snd_usb_create_mixer(struct snd_usb_audio *chip, int ctrlif,