EHCI_QTD_SET_PID
EHCI_QTD_SET_PID(rd ? EHCI_QTD_PID_IN : EHCI_QTD_PID_OUT) |
EHCI_QTD_SET_PID(EHCI_QTD_PID_SETUP) |
EHCI_QTD_SET_PID(usbd_xfer_isread(xfer) ?