Re: USB devices fail unnecessarily on unpowered hubs

From: David Liontooth
Date: Fri Jun 02 2006 - 15:56:09 EST


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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