Index: uhci.c
===================================================================
RCS file: /cvsroot/src/sys/dev/usb/uhci.c,v
retrieving revision 1.283
diff -p -u -r1.283 uhci.c
--- uhci.c	3 Sep 2018 16:29:34 -0000	1.283
+++ uhci.c	10 Sep 2018 19:59:54 -0000
@@ -2568,7 +2568,8 @@ uhci_device_ctrl_start(struct usbd_xfer 
 	memcpy(KERNADDR(&upipe->ctrl.reqdma, 0), req, sizeof(*req));
 	usb_syncmem(&upipe->ctrl.reqdma, 0, sizeof(*req), BUS_DMASYNC_PREWRITE);
 
-	mutex_enter(&sc->sc_lock);
+	if (!sc->sc_bus.ub_usepolling)
+		mutex_enter(&sc->sc_lock);
 
 	/* Set up data transaction */
 	if (len != 0) {
@@ -2670,7 +2671,8 @@ uhci_device_ctrl_start(struct usbd_xfer 
 			    uhci_timeout, xfer);
 	}
 	xfer->ux_status = USBD_IN_PROGRESS;
-	mutex_exit(&sc->sc_lock);
+	if (!sc->sc_bus.ub_usepolling)
+		mutex_exit(&sc->sc_lock);
 
 	return USBD_IN_PROGRESS;
 }