linux-kernel - Re: USB device PM oddity in 3.5

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Date:	Thu, 24 May 2012 16:48:26 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Josh Boyer <jwboyer@...hat.com>
cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: USB device PM oddity in 3.5

On Thu, 24 May 2012, Josh Boyer wrote:

> I'm testing Linus' tree as the merge window happens, and I've hit an
> issue with what I believe is USB device power management (or something)
> that is causing my mouse and keyboard to become unresponsive.  After a
> very short time of non-use, either device will cut out.  I can move the
> mouse around but it doesn't relay to the screen and I noticed this is
> because the laser is turned off.  If I click a button on it, it will
> turn back on and function again until a small period of non-use.  The
> keyboard exhibits similar behavior, "ignoring" the first few key strokes
> until it wakes back up.
> 
> I found this thread:
> 
> http://thread.gmane.org/gmane.linux.usb.general/64292
> and
> http://marc.info/?t=133552726500001&r=1&w=2
> 
> which have similar symptoms, but the kernels I'm using have the
> subsequent patches applied.  I'm doing a git bisect at the moment, with
> 72c04af as the starting good commit and 61011677 as the first bad.  I'll
> let you know what comes of this, but I thought I'd mail about it now in
> case anyone has any ideas.

It sounds like you have autosuspend enabled on the mouse and keyboard, 
and they don't work very well with it.  Setting the sysfs power/control 
attributes for the two devices to "on" will prevent autosuspend.

I don't know why this would have started happening after a kernel 
upgrade.  Those settings are normally controlled by userspace apps.  
Let us know what you find.

Alan Stern

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