XHCI_ERDP_LO
XRWRITE4(sc, XHCI_ERDP_LO(0), (uint32_t)paddr);
XRREAD4(sc, XHCI_ERDP_HI(0)), XRREAD4(sc, XHCI_ERDP_LO(0))));
XRWRITE4(sc, XHCI_ERDP_LO(0), 0);
XRWRITE4(sc, XHCI_ERDP_LO(0), 0);
XRWRITE4(sc, XHCI_ERDP_LO(0), ((uint32_t)paddr) | XHCI_ERDP_LO_BUSY);