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

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Date:	Wed, 25 Feb 2009 18:13:45 -0800
From:	Arve Hjønnevåg <arve@...roid.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, Ingo Molnar <mingo@...e.hu>,
	"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 5:27 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
>
> On Wed, 25 Feb 2009, Arve Hjønnevåg wrote:
>>
>> Do you plan to fix edge triggered wakeup interrupts? It still looks
>> like edge triggered wakeup interrupts that occur between
>> suspend_device_irqs and local_irq_disable will not cause a wakeup.
>
> IF we ever see this as a real issue, we can either see it in the
> IRQ_PENDING flag, or we can mark such interrupts specially. So it would be
> solvable. That said, I haven't actually heard any real usage cases. Normal
> wakeup events are _not_ interrupts in the regular "device interrupt
> controller" sense.
>
> So can you actually point to an explicit example of something where this
> is a real issue?

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.

-- 
Arve Hjønnevåg
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