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

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Message-ID: <d6200be20902251931lf563c2aw43d5266e9677e168@mail.gmail.com>
Date:	Wed, 25 Feb 2009 19:31:51 -0800
From:	Arve Hjønnevåg <arve@...roid.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"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

On Wed, Feb 25, 2009 at 7:00 PM, Ingo Molnar <mingo@...e.hu> wrote:
>
> * 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.

That would not work without wakelocks support, since the interrupt
could occur after suspend_late which is the last chance for the driver
to abort sleep. (The patch also breaks my current wakelock
implementation since I use a suspend_late hook to abort sleep, but
this should be easy to fix)

> 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:

I think the right fix is for any interrupt that has IRQ_WAKEUP set to
abort suspend if it is pending. I don't know if anyone relies on these
interrupts being dropped now though.

-- 
Arve Hjønnevåg
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