ATW_SYNCTL_RD
if (ATW_ISSET(sc, ATW_SYNCTL, ATW_SYNCTL_RD|ATW_SYNCTL_WR) == 0)
if (ATW_ISSET(sc, ATW_SYNCTL, ATW_SYNCTL_RD) == 0)
ATW_CLR(sc, ATW_SYNCTL, ATW_SYNCTL_RD);
sc->sc_synctl_rd = reg | ATW_SYNCTL_RD;