static int xhci_fire_ctl_transfer(XHCIState *xhci, XHCITransfer *xfer)
{
    XHCITRB *trb_setup, *trb_status;
    uint8_t bmRequestType;

    trb_setup = &xfer->trbs[0];
    trb_status = &xfer->trbs[xfer->trb_count-1];

    trace_usb_xhci_xfer_start(xfer, xfer->slotid, xfer->epid, xfer->streamid);

    /* at most one Event Data TRB allowed after STATUS */
    if (TRB_TYPE(*trb_status) == TR_EVDATA && xfer->trb_count > 2) {
        trb_status--;
    }

    /* do some sanity checks */
    if (TRB_TYPE(*trb_setup) != TR_SETUP) {
        DPRINTF("xhci: ep0 first TD not SETUP: %d\n",
                TRB_TYPE(*trb_setup));
        return -1;
    }
    if (TRB_TYPE(*trb_status) != TR_STATUS) {
        DPRINTF("xhci: ep0 last TD not STATUS: %d\n",
                TRB_TYPE(*trb_status));
        return -1;
    }
    if (!(trb_setup->control & TRB_TR_IDT)) {
        DPRINTF("xhci: Setup TRB doesn't have IDT set\n");
        return -1;
    }
    if ((trb_setup->status & 0x1ffff) != 8) {
        DPRINTF("xhci: Setup TRB has bad length (%d)\n",
                (trb_setup->status & 0x1ffff));
        return -1;
    }

    bmRequestType = trb_setup->parameter;

    xfer->in_xfer = bmRequestType & USB_DIR_IN;
    xfer->iso_xfer = false;
    xfer->timed_xfer = false;

    if (xhci_setup_packet(xfer) < 0) {
        return -1;
    }
    xfer->packet.parameter = trb_setup->parameter;

    usb_handle_packet(xfer->packet.ep->dev, &xfer->packet);

    xhci_complete_packet(xfer);
    if (!xfer->running_async && !xfer->running_retry) {
        xhci_kick_ep(xhci, xfer->slotid, xfer->epid, 0);
    }
    return 0;
}

static int xhci_fire_ctl_transfer(XHCIState *xhci, XHCITransfer *xfer)
{
    XHCITRB *trb_setup, *trb_status;
    uint8_t bmRequestType;

    trb_setup = &xfer->trbs[0];
    trb_status = &xfer->trbs[xfer->trb_count-1];

    trace_usb_xhci_xfer_start(xfer, xfer->slotid, xfer->epid, xfer->streamid);

    /* at most one Event Data TRB allowed after STATUS */
    if (TRB_TYPE(*trb_status) == TR_EVDATA && xfer->trb_count > 2) {
        trb_status--;
    }

    /* do some sanity checks */
    if (TRB_TYPE(*trb_setup) != TR_SETUP) {
        DPRINTF("xhci: ep0 first TD not SETUP: %d\n",
                TRB_TYPE(*trb_setup));
        return -1;
    }
    if (TRB_TYPE(*trb_status) != TR_STATUS) {
        DPRINTF("xhci: ep0 last TD not STATUS: %d\n",
                TRB_TYPE(*trb_status));
        return -1;
    }
    if (!(trb_setup->control & TRB_TR_IDT)) {
        DPRINTF("xhci: Setup TRB doesn't have IDT set\n");
        return -1;
    }
    if ((trb_setup->status & 0x1ffff) != 8) {
        DPRINTF("xhci: Setup TRB has bad length (%d)\n",
                (trb_setup->status & 0x1ffff));
        return -1;
    }

    bmRequestType = trb_setup->parameter;

    xfer->in_xfer = bmRequestType & USB_DIR_IN;
    xfer->iso_xfer = false;
    xfer->timed_xfer = false;

    if (xhci_setup_packet(xfer) < 0) {
        return -1;
    }
    xfer->packet.parameter = trb_setup->parameter;

    usb_handle_packet(xfer->packet.ep->dev, &xfer->packet);

    xhci_complete_packet(xfer);
    if (!xfer->running_async && !xfer->running_retry) {
        xhci_kick_ep(xhci, xfer->slotid, xfer->epid, 0);
    }
    return 0;
}
