linux-kernel - Re: Power-managing devices that are not of interest at some point in time

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Date:	Sat, 19 Jul 2014 11:21:52 -0700
From:	Dmitry Torokhov <dtor@...gle.com>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Benson Leung <bleung@...omium.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Patrik Fimml <patrikf@...omium.org>,
	Bastien Nocera <hadess@...ess.net>, linux-pm@...r.kernel.org,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Power-managing devices that are not of interest at some point in time

On Saturday, July 19, 2014 01:59:01 PM Alan Stern wrote:
> On Sat, 19 Jul 2014, Benson Leung wrote:
> > > This raises an interesting question.  Suppose the system gets suspended
> > > while the lid is closed.  At that point, shouldn't wakeup devices be
> > > enabled, even if they were already inhibited?
> > 
> > It's possible that this could be a policy decision, ie, whether
> > power/wakeup is set to enabled for those devices or not.
> > However, I'd say that there's only one policy that makes sense in that
> > case : wakeups should be disabled while suspended.
> > 
> > If we inhibited the device during runtime to prevent stray input
> > events from being generated, it wouldn't make sense to allow the
> > device to potentially generate an accidental wakeup while suspended.
> 
> That doesn't really make sense.  If you're afraid of a device
> generating spurious wakeup events when the lid is closed, you should
> never enable it for wakeup.  After all, one of the first things that
> people often do after suspending their laptop is close the lid.

That's a fair point, and I think should be done by default. But that does not 
change what Benson said - I think if we inhibited the device it should stay 
inhibited across system suspend, including being disabled as wakeup source 
even if it could be enabled as such.

Thanks,
Dmitry

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