RB_FLUSH
rtsx_pci_write_register(pcr, RBCTL, RB_FLUSH, RB_FLUSH);
rtsx_pci_write_register(pcr, RBCTL, RB_FLUSH, RB_FLUSH);
rtsx_pci_write_register(pcr, RBCTL, RB_FLUSH, RB_FLUSH);
rtsx_pci_write_register(pcr, RBCTL, RB_FLUSH, RB_FLUSH);