From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [patch 2/2] support for UHCI suspend / remote wake up
Date: Wed, 01 Dec 2010 18:17:47 +0100
Message-ID: <4CF6833B.7000103@redhat.com>
References: <20101125170439.548474575@redhat.com> <20101125170602.676792336@redhat.com> <4CF665CE.70600@redhat.com> <20101201165821.GA13677@amt.cnet>
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Cc: qemu-devel@nongnu.org, kvm <kvm@vger.kernel.org>,
	Matthew Garrett <mjg59@srcf.ucam.org>,
	Adam Jackson <ajax@redhat.com>,
	Glauber de Oliveira Costa <gcosta@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
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> I was seeing bus disconnects when not clearing port resume bit properly.
>
>>>               port->ctrl&= ~(val&   0x000a);
>>> +            port->ctrl&= ~(port->ctrl&   0x0040); /* clear port resume detected */
>>>           }
>>
>> This chunk looks suspicious ...
>>
>> I suspect the port suspend/resume emulation isn't complete.

The bug is that the port resume bit is masked out from guest writes, so 
the guest hasn't a chance to clear it ...

cheers,
   Gerd

PS: http://cgit.freedesktop.org/spice/qemu/log/?h=usb.1