UMSR_DSR
if (ISSET(combits, UMSR_DSR))
sc->sc_msr |= UMSR_DSR;
sc->sc_msr |= UMSR_DSR;
sc->sc_msr |= UMSR_DSR;
sc->sc_msr |= UMSR_DSR;
sc->sc_msr &= ~UMSR_DSR;
sc->sc_msr |= UMSR_DSR;
SET(sc->sc_msr, UMSR_DSR);
sc->sc_msr |= UMSR_DSR;