linux-kernel - Re: [RFC][PATCH 2/2] PM: Rework handling of interrupts during suspend-resume

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Date:	Thu, 26 Feb 2009 04:00:50 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Arve Hjønnevåg <arve@...roid.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Len Brown <lenb@...nel.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [RFC][PATCH 2/2] PM: Rework handling of interrupts during
	suspend-resume


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> 
> 
> On Wed, 25 Feb 2009, Arve Hjønnevåg wrote:
> >
> > On the msm platform the keyboard driver currently leave the interrupts
> > enabled when suspended. If the interrupt handler is called, we use a
> > wakelock to abort suspend (without wakelocks you would need to set a
> > flag and abort in suspend_late instead). If the interrupt occurs after
> > local_irq_disable, it will still be pending when we get to the suspend
> > enter hook and suspend will be aborted there.
> > 
> > As far as I can tell, this change breaks this. If you press a key at
> > the right time, it will be ignored.
> 
> Is the irq on a private non-shared interrupt line? If so, you 
> could just mark it as IRQF_TIMER, and the irq disable logic 
> won't touch it.

Hm, if that solves the problem then it would be nice to have a 
new IRQF_NO_SUSPEND flag for it, in addition to IRQF_TIMER:

./interrupt.h: * IRQF_TIMER - Flag to mark this interrupt as timer interrupt
./interrupt.h:#define IRQF_TIMER		0x00000200

to express such quirks cleanly.

and the suspend code can check the (IRQF_TIMER | 
IRQF_NO_SUSPEND) mask - so no extra cost.

Right now we have a clean enumeration of timer interrupts, would 
be nice to keep that.

	Ingo
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