Messages in this thread | | | Date | Thu, 26 Feb 2009 16:00:52 -0800 | Subject | Re: [RFC][PATCH 2/2] PM: Rework handling of interrupts during suspend-resume | From | Arve Hjønnevåg <> |
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On Thu, Feb 26, 2009 at 3:10 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote: > On Thursday 26 February 2009, Arve Hjønnevåg wrote: >> On Thu, Feb 26, 2009 at 2:10 PM, Linus Torvalds >> <torvalds@linux-foundation.org> wrote: >> > >> > >> > On Thu, 26 Feb 2009, Rafael J. Wysocki wrote: >> >> >> >> Well, how exactly the $subject patch does cause this problem to happen? >> > >> > Rafael, the problem is that if an interrupt happens while it's disabled - >> > but before the CPU has actually turned all interrupts off - the CPU will >> > ACK the interrupt (but just set a flag for it being PENDING), so now the >> > chipset logic around it will not see it as pending any more, so now the >> > chipset won't auto-wake the CPU immediately (or more likely, it won't >> > even suspend it). >> > >> > It's trivial to fix multiple ways, so I wouldn't worry. The most trivial >> > way is to just have some sysdev drievr code simply do something like >> > >> > static int sysdev_suspend() >> > { >> > for_each_irq(irq,desc) { >> > if (!(desc->flags & IRQF_WAKE)) >> > continue; >> > if (desc->flags & IRQ_PENDING) >> > return -EBUSY; >> > } >> > return 0; >> > } >> > >> > and that should automatically mean that if any irq is pending, the suspend >> > will fail and we'll immediately wake up again. >> > >> > It looks trivial, and I don't understand why Arve can't just do the sysdev >> > thing. >> >> I can. My point is that the patch breaks our existing code. > > Is that a mainline kernel code?
No, the msm suspend support has not been merged.
> >> If anyone else uses edge triggered wakeup interrupt it may break from them as >> well. The main question if this should be fixed separately for every >> platform that needs it, or if pending wakeup interrupts should always >> abort sleep. > > Well, I'm not really sure if this is the problem. In fact the problem is that > you have a regular device the interrupt of which can be a wake-up one. I think
Is that not a common case and what enable_irq_wake is for?
> the problem wouldn't have existed at all if it had been a sysdev. Is that > correct?
How many sysdevs use interrupts?
I found may drivers in the mainline kernel that use enable_irq_wake, but I did not see any that handle this race condition.
-- Arve Hjønnevåg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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