XHCI_RTSOFF
sc->sc_runt_off = XREAD4(sc, capa, XHCI_RTSOFF) & ~0xF;
sc->sc_runt_off = XREAD4(sc, capa, XHCI_RTSOFF) & ~0x1F;
case XHCI_RTSOFF: /* 0x18 */