On 6/3/06, Xiaofan Chen <xiaofanc@gmail.com> wrote:
> > I just came across an interesting thread in the linux-usb-devel mailing
> > list.
> > http://marc.theaimsgroup.com/?l=linux-kernel&m=114915375324284&w=2
> >
> > The main problem is that lots of USB device does not follow the USB
> > specification in terms of power budget and it is now up to the Linux
> > USB developers to decide how to deal with them.
> >

Finally the issue is considered closed.

---------- Forwarded message ----------
From: David Liontooth <liontooth@cogweb.net>
Date: Jun 3, 2006 3:49 AM
Subject: Re: [linux-usb-devel] USB devices fail unnecessarily on unpowered hubs
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrew Morton <akpm@osdl.org>, Greg KH <greg@kroah.com>,
linux-kernel@vger.kernel.org, linux-usb-devel@lists.sourceforge.net


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
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