linux-kernel - Re: [Regression] USB wakeup problem on Toshiba Portege R500

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Date:	Thu, 8 Jan 2009 20:54:44 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Frans Pop <elendil@...net.nl>
Cc:	oliver@...kum.org, stern@...land.harvard.edu, gregkh@...e.de,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-pm@...ts.linux-foundation.org, pavel@...e.cz,
	torvalds@...ux-foundation.org
Subject: Re: [Regression] USB wakeup problem on Toshiba Portege R500

On Thursday 08 January 2009, Frans Pop wrote:
> Rafael J. Wysocki wrote:
> > On Thursday 08 January 2009, Oliver Neukum wrote:
> >> Am Thursday 08 January 2009 17:36:12 schrieb Rafael J. Wysocki:
> >> You are making a very persuasive argument for reverting it.
> >> But what about laptops that only have a USB keyboard?
> > 
> > Well, up to and including 2.6.28 they needed to echo 'enable' to the USB
> > controllers' /sys/devices/.../power/wakeup files, so if the patch is
> > reverted, they won't be worse off than they were day before
> > yesterday. :-) 
> > 
> > Perhaps we can choose the default depending on whether or not any HID
> > devices are attached to given controller?
> 
> Is "resume on keyboard activity" really all that needed? Both my laptops 
> and my desktop resume fine after pressing the power button.
> 
> Also consider the following cases:
> - laptop has been suspended with external USB mouse connected
>   - mouse is moved (accidentally or because it is in the way of a coffee
>     cup)
>   - mouse cable is removed before putting the laptop in a bag for
>     transport
> - laptop is in docking station with USB mouse/kbd connected to that
>   - again, mouse gets moved for some reason
>   - laptop is undocked while suspended
>   - or the reverse: laptop gets docked

One more case (a real-life example actually):
- There is a USB wireless mouse attached to the box while suspending and the
  mouse is powered off by pressing a button on it.  The mouse's radio receiver
  remains in a USB port on the box.  Now, if the mouse is powered off again,
  the box will resume.  What if that happens accidentally while the box is
  being carried in a backpack?

> IMO it is not desirable that the system gets resumed as a result of any of 
> those actions. I'm not complete sure that it would in all those cases, 
> but have they been considered?
> 
> And in general I've always been in favor of things only happening 
> automagically if I've explicitly asked for that, and not by default.

I have to say I agree.

Thanks,
Rafael
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