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Date: Thu, 13 Mar 2003 09:00:33 -0800 (PST)
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Cc: 
From: Henning Meier-Geinitz <henning@meier-geinitz.de>
Subject: Re: kern/41281: USB scanning works only once
Reply-To: Henning Meier-Geinitz <henning@meier-geinitz.de>
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The following reply was made to PR kern/41281; it has been noted by GNATS.

From: Henning Meier-Geinitz <henning@meier-geinitz.de>
To: Nate Lawson <nate@root.org>
Cc: freebsd-gnats-submit@freebsd.org
Subject: Re: kern/41281: USB scanning works only once
Date: Thu, 13 Mar 2003 17:58:14 +0100

 Hi,
 
 On Wed, Mar 12, 2003 at 09:30:16PM -0800, Nate Lawson wrote:
 > Please send me a pointer to the relevant code in the linux driver and I
 > may be able to put together a workaround.
 
 Well, the problem is that there is no special code in the Linux kernel
 for working-around the problem. My observation is that the Linux
 kernel invokes functions that change the USB toggle (e.g.
 set_configuration) only on driver load/plugging in the device. BSD
 seems to change the toggle on every open() (and/or close()?) of a USB
 device file. That's not wrong, it just triggers this hardware bug.
 
 I don't know the FreeBSD kernel internals but I gues it's not easy to
 work around this bug without changing the way how USB is handled in
 general.
 
 E.g. set_configuration in Linux is only called in usb_new_device()
 (drivers/usb/core/usb.c) which is called by the hub driver on device
 connect. That's with linux 2.5.64.
 
 Bye,
   Henning

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