sc_ucr3
uint32_t ucr3 = sc->sc_ucr3;
if (ucr3 != sc->sc_ucr3) {
sc->sc_ucr3 = ucr3;
if (ISSET(sc->sc_ucr3, IMX_UCR3_DSR))
sc->sc_ucr3 &= ~IMXUART_INTRS_UCR3;
sc->sc_ucr3 |= IMX_UCR3_DSR;
bus_space_write_4(iot, ioh, IMX_UCR3, sc->sc_ucr3);