linux-kernel - Re: [PATCH] PM: suspend_device_irqs(): don't disable wakeup IRQs

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Message-id: <4A1A4297.50809@samsung.com>
Date:	Mon, 25 May 2009 16:02:47 +0900
From:	Kim Kyuwon <q1.kim@...sung.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Kim Kyuwon <chammoru@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...e.hu>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Kevin Hilman <khilman@...prootsystems.com>
Subject: Re: [PATCH] PM: suspend_device_irqs(): don't disable wakeup IRQs

Rafael J. Wysocki wrote:
> On Saturday 23 May 2009, Kim Kyuwon wrote:
>> On Sat, May 23, 2009 at 7:29 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
>>> On Saturday 23 May 2009, Kim Kyuwon wrote:
> [--snip--]
>>>> You changed the really important part of Linux, which may affect most
>>>> processor architectures. I think you should be careful. If some of
>>>> architectures can't take care of it (they can implement
>>>> disable_irq_wake correctly in H/W level, will you revert your changes?
>>> No, the changes are not going to be reverted.  In fact things should have been
>>> done like this already much earlier.
>>>
>>> Now, do you have any particular example of a problem related to these changes
>>> or is it only a theoretical issue?
>> I'd CCing you when I'm sending a mail for this particular example of a example.
>> http://markmail.org/thread/fvt7d62arofon5xx
> 
> Well, as I said above, reverting the changes that introduced
> [suspend|resume]_device_irqs() is not an option, becuase it was the only sane
> way to achieve the goal they were added for.  So, we need to fix the wake-up
> problem on your platform with the assumption that
> [suspend|resume]_device_irqs() are going to stay.
> 
> For starters, would it be possible to teach the 'disable' hook of your
> platform's interrupt controller not to mask the IRQs that have both
> IRQ_WAKEUP and IRQ_SUSPENDED set?  That apparently would work around the
> wake-up interrupts problem.

Thank you for considering this issue and spending your time. In order to 
make your idea work, we need to add a dummy 'set_wake' hook which 
returns always zero. Anyway, IMO, I think your idea is good to work 
around this problem. But Kevin Hilman(OMAP PM Maintainer) would make 
final decision.

Buy the way, how can you handle the problem that a few interrupt are 
discarded in a small window? I can be sure they are discarded, because I 
have debugged defects which generate in sleep/resume state hundreds of 
times on ARM Processors(PXA310, S3C6410, OMAP3430). Wake-up interrupts 
are generated as soon as arch_suspend_enable_irqs() invoked.

Regards,
Kyuwon
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