From: Jan Scholz <scholz@fias.uni-frankfurt.de>
To: linux-kernel@vger.kernel.org
Cc: stern@rowland.harvard.edu
Cc: gregkh@suse.de
Cc: marcel@holtmann.org
Subject: [BUG] Regression in v2.6.28 introduced by: 'USB: skip Set-Interface(0) if already in altsetting 0'
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Date: Fri, 02 Jan 2009 12:04:17 +0100
Message-ID: <87ljtu7yvi.fsf@scholz.fias.uni-frankfurt.de>
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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>

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