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

Ingo Molnar
2009-02-24T23:10:40Z

* Rafael J. Wysocki <rjw@sisk.pl> wrote:

> On Tuesday 24 February 2009, Linus Torvalds wrote:
> >
> > On Tue, 24 Feb 2009, Rafael J. Wysocki wrote:
> > >
> > > > The only safe way on x86 to shutdown a level triggered ioapic irq
> > > > outside of irq context is for the driver to program the hardware to
> > > > not generate an irq.
> > >
> > > Well, that changes things quite a bit, because it means we can't change the
> > > suspend-resume sequence in a way we thought we could without fixing all
> > > drivers first, but this is exactly what we'd like to avoid by changing the
> > > core.
> >
> > Calling "disable_irq()" is perfectly fine.
> >
> > What is not possible on that broken IO-APIC (among other
> > things) is to actually turn the interrupts off at the apic
> > (ie the whole ->shutdown() thing). But that's not what we
> > even want to do. What we care about is just disabling the
> > interrupt from a drievr perspective.
> >
> > IOW, the patches I have seen are fine, and all the comments
> > from Eric are just confusion about what we want done.
>
> Ah, OK. Thanks for the explanation, I got confused too.
>
> > WE DO NOT WANT TO TURN OFF THE IO-APIC. That may or may
> > happen later, but that's totally unrelated to this whole
> > "suspend_device_irq()" thing.
>
> Yeah.

We definitely dont want to turn off x86 IO-APICs - the timer IRQ
goes via one of them.

Ingo