Date: Fri, 2 Jan 2009 13:01:09 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Jan Scholz <scholz@fias.uni-frankfurt.de>
Cc: linux-kernel@vger.kernel.org, stern@rowland.harvard.edu, gregkh@suse.de,
       marcel@holtmann.org
Subject: Re: [BUG] Regression in v2.6.28 introduced by: 'USB: skip
	Set-Interface(0) if already in altsetting 0'
Message-ID: <20090102120109.GC3027@elte.hu>
References: <87ljtu7yvi.fsf@scholz.fias.uni-frankfurt.de>
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* Jan Scholz <scholz@fias.uni-frankfurt.de> wrote:

> Hi,
> 
> In v2.6.28 my usb bluetooth device disappears after suspend to ram:
> 
> $ hcitool dev
> Devices:
> 	hci0	00:0D:93:15:D6:E8
> $ echo mem > /sys/power/state 
> $ hcitool dev
> Devices:
> $
> 
> The problem does not occur with the (older) hci_usb.ko, but only with
> btusb.ko.
>  
> This is the output of lsusb:
> Bus 001 Device 003: ID 05ac:8203 Apple Computer, Inc. Bluetooth HCI
> 
> Bisecting finds commit 24c0996 (USB: skip Set-Interface(0) if already in
> altsetting 0) as the first bad commit, and indeed if I use 2.6.28 with
> 24c0996 reverted, the bluetooth device survives suspend to ram.
> 
> If you need more information/test/etc please let me know.
> 
> Regards,
> Jan
> 
> > commit 24c0996a6b73e2554104961afcc8659534503e0d
> > Author: Alan Stern <stern@rowland.harvard.edu>
> > Date:   Mon Dec 1 10:24:41 2008 -0500
> >
> >     USB: skip Set-Interface(0) if already in altsetting 0
> >
> >     When a driver unbinds from an interface, usbcore always sends a
> >     Set-Interface request to reinstall altsetting 0.  Unforunately, quite
> >     a few devices have buggy firmware that crashes when it receives this
> >     request.
> >
> >     To avoid such problems, this patch (as1180) arranges to send the
> >     Set-Interface request only when the interface is not already in
> >     altsetting 0.
> >
> >     Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
> >     Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

here's a fix patch that appears to be dealing with aspects of this commit:

  http://lkml.org/lkml/2009/1/2/47

you might want to give it a try.

	Ingo
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