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Could you try the attached patch? > >        Regards >                Oliver I think, that will not work. With this patch, if a ZLP comes in, WDM_READ is not set, so wdm_read() won't submit another read urb if resp_count is not zero (won't call service_outstanding_interrupt), and we are not doing here, in wdm_in_callback neither. So the receiving just gets stuck. That's exactly the reason I did what I did in the patch I sent. Best regards, Robert Hodaszi