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Message-ID: <44809653.9010203@cogweb.net>
Date: Fri, 02 Jun 2006 12:49:39 -0700
From: David Liontooth <liontooth@cogweb.net>
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To: Alan Stern <stern@rowland.harvard.edu>
CC: Greg KH <greg@kroah.com>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org, linux-usb-devel@lists.sourceforge.net
Subject: Re: USB devices fail unnecessarily on unpowered hubs
References: <Pine.LNX.4.44L0.0606021109390.7076-100000@iolanthe.rowland.org>
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Alan Stern wrote:
> Trying to draw too much current from an unpowered hub can and does cause 
> data loss.
>   
I consider this issue closed; thank you for looking at it. The
workaround is reasonably simple for the common situation of mounting a
USB stick on a keyboard, perhaps with a mouse attached in a second port:

NUM="$(dmesg | tail -n 3 | grep -r 'new full speed USB device' | cut -b
5-9)"
echo -n 1 >/sys/bus/usb/devices/$NUM/bConfigurationValue

with the understanding this breaks USB power rules and can lead to data
loss.

Dave