diff -up qemu-2.7.0/hw/usb/redirect.c~ qemu-2.7.0/hw/usb/redirect.c

--- qemu-2.7.0/hw/usb/redirect.c~	2016-09-02 17:34:20.000000000 +0200

+++ qemu-2.7.0/hw/usb/redirect.c	2016-10-10 09:18:35.319562664 +0200

@@ -2036,18 +2036,22 @@ static void usbredir_interrupt_packet(vo

     }

     if (ep & USB_DIR_IN) {

+        bool q_was_empty;

+

         if (dev->endpoint[EP2I(ep)].interrupt_started == 0) {

             DPRINTF("received int packet while not started ep %02X\n", ep);

             free(data);

             return;

         }

-        if (QTAILQ_EMPTY(&dev->endpoint[EP2I(ep)].bufpq)) {

-            usb_wakeup(usb_ep_get(&dev->dev, USB_TOKEN_IN, ep & 0x0f), 0);

-        }

+        q_was_empty = QTAILQ_EMPTY(&dev->endpoint[EP2I(ep)].bufpq);

         /* bufp_alloc also adds the packet to the ep queue */

         bufp_alloc(dev, data, data_len, interrupt_packet->status, ep, data);

+

+        if (q_was_empty) {

+            usb_wakeup(usb_ep_get(&dev->dev, USB_TOKEN_IN, ep & 0x0f), 0);

+        }

     } else {

         /*

          * We report output interrupt packets as completed directly upon