VRC2_PWM_LCDDUTY
sc->sc_raw_duty = vrc4172pwm_read(sc, VRC2_PWM_LCDDUTY);
vrc4172pwm_write(sc, VRC2_PWM_LCDDUTY, raw);
duty = vrc4172pwm_read(sc, VRC2_PWM_LCDDUTY);