=== ./xhci.c
==================================================================
--- ./xhci.c	(revision 255094)
+++ ./xhci.c	(local)
@@ -385,10 +385,6 @@
 	sc->sc_exit_lat_max = XHCI_HCS3_U1_DEL(temp) +
 	    XHCI_HCS3_U2_DEL(temp) + 250 /* us */;
 
-	temp = XREAD4(sc, oper, XHCI_USBSTS);
-
-	/* clear interrupts */
-	XWRITE4(sc, oper, XHCI_USBSTS, temp);
 	/* disable all device notifications */
 	XWRITE4(sc, oper, XHCI_DNCTRL, 0);
 
@@ -1479,7 +1475,9 @@
 	USB_BUS_LOCK(&sc->sc_bus);
 
 	status = XREAD4(sc, oper, XHCI_USBSTS);
-	if (status == 0)
+	iman = XREAD4(sc, runt, XHCI_IMAN(0));
+
+	if (status == 0 && (iman & XHCI_IMAN_INTR_PEND) == 0)
 		goto done;
 
 	/* acknowledge interrupts */
@@ -1488,11 +1486,8 @@
 
 	DPRINTFN(16, "real interrupt (status=0x%08x)\n", status);
  
-	if (status & XHCI_STS_EINT) {
+	if (iman & XHCI_IMAN_INTR_PEND) {
 
-		/* acknowledge pending event */
-		iman = XREAD4(sc, runt, XHCI_IMAN(0));
-
 		/* reset interrupt */
 		XWRITE4(sc, runt, XHCI_IMAN(0), iman);