LP_ENABLE_IRQ
sc->sc_irq = LP_HAS_IRQ | LP_USE_IRQ | LP_ENABLE_IRQ;
if (sc->sc_irq & LP_ENABLE_IRQ)
sc->sc_irq &= (~LP_ENABLE_IRQ);
sc->sc_irq |= LP_ENABLE_IRQ;
sc->sc_irq &= (~LP_ENABLE_IRQ);
(sc->sc_irq & LP_ENABLE_IRQ)?