ehci: update irq on reset

After clearing the status register we also have to update the irq line
status.  Otherwise a irq which happends to be pending at reset time
causes a interrupt storm.  And the guest can't stop as the status
register doesn't indicate any pending interrupt.

Both NetBSD and FreeBSD hang on shutdown because of that.

Cc: qemu-stable@nongnu.org
Reported-by: Andrey Korolyov <andrey@xdel.ru>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1453203884-4125-1-git-send-email-kraxel@redhat.com

hw/usb/hcd-ehci.c

@@ -866,6 +866,7 @@ void ehci_reset(void *opaque)
     s->usbsts = USBSTS_HALT;
     s->usbsts_pending = 0;
     s->usbsts_frindex = 0;
+    ehci_update_irq(s);
 
     s->astate = EST_INACTIVE;
     s->pstate = EST_INACTIVE;