wskbd_vol
struct wskbd_vol spkr, mic;
wskbd_initvol(struct audio_softc *sc, struct wskbd_vol *vol, char *cn, char *dn)
wskbd_mixer_update(struct audio_softc *sc, struct wskbd_vol *vol)
struct wskbd_vol *vol;
struct wskbd_vol *vol;