> Subject: Re: [EE] Software power cycling of USB port? (Linux)
> 
> 
> On Fri, Mar 7, 2008 at 8:37 AM, Martin <martin@nnytech.net> wrote:
> >
> >  You have to reload the driver kernel module for the device 
> or possibly
> >  the USB bridge.
> >
> >  You can't shut off power to a USB port through software. 
> (correct me if
> >  I'm wrong)
> 
> In Linux or in general?  I thought this is how Windows does the
> 'Safely Remove Device'.  If you have a flash drive in there with an
> LED, the LED goes out, even though it is still plugged in.
> 
> There should be a file called state in a subdir like
> /sys/bus/usb/devices/1-0:1.0/power, and:
> echo "2" > /sys/bus/usb/devices/1-0:1.0/power/state
> is supposed to power it off.  But on my system (2.6.23) the state file
> does not exist. :(
> 
> Alex
> -- 

The two front USB ports on my computer case have the power
leads wired in parallel.
I'm guessing that means that the OS cannot selectively 
control power to those ports.

Lyle


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