linux-kernel - Re: [linux-pm] x86: Expected system state when resumed

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Message-Id: <200907221630.50154.rjw@sisk.pl>
Date:	Wed, 22 Jul 2009 16:30:49 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	dsaxena@...xity.net
Cc:	linux-pm@...ts.osdl.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [linux-pm] x86: Expected system state when resumed

On Wednesday 22 July 2009, Deepak Saxena wrote:
> On Jul 21 2009, at 22:48, Rafael J. Wysocki was caught saying:
> > On Tuesday 21 July 2009, Deepak Saxena wrote:
> > > 
> > > I am working on getting suspend/resume working on an x86 system
> > > (OLPC XO-1.5) where we are implementing ACPI based suspend/resume
> > > using Open Firmware and what I am seeing right now is that on 
> > > resume, we're not receiving interrupts so the system locks
> > > up in the suspend path when msleep() is called from the EHCI
> > > HCD resume code. lapic_resume() is being called so the APIC
> > > is being restored.  I'm looking for information on what else
> > > Linux's expectation from the firmware when control is handed back 
> > > before I start dumping every system register pre and post resume.
> > 
> > If that's 2.6.30 or later and your timer interrupt is MSI, for example, please
> > check if the timer interrupt is marked as IRQF_TIMER.  If it's not,
> > suspend_device_irqs() will mark it as disabled and it won't work during
> > early resume.
> 
> Thanks. I am using 2.6.30.1 and the standard x86 HPET driver which has 
> IRQF_TIMER set so this is not the issue. I've determined that if I boot 
> with "noapic", I can suspend/resume, but the system runs very slow as the
> PATA controller is now polled instead of irq driven.

So it looks like with IO-APIC enabled the timer interrupts don't reach the CPU
during resume, which indicates that the post-resume status of the IO-APIC is
somewhat not as expected.

Best,
Rafael
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