pwm_backlight_set
pwm_backlight_set(sc, default_level, true);
pwm_backlight_set(sc, n, true);
pwm_backlight_set(sc, enable ? sc->sc_curlevel : 0, false);
pwm_backlight_set(sc, n + 1, true);
pwm_backlight_set(sc, n - 1, true);
static void pwm_backlight_set(struct pwm_backlight_softc *, u_int, bool);