linux-kernel - Re: [PATCH] Quirk to fix suspend/resume on Lenovo Edge 11,13,14,15

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Message-ID: <alpine.LFD.2.00.1101132353210.2678@localhost6.localdomain6>
Date:	Thu, 13 Jan 2011 23:55:58 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Borislav Petkov <bp@...64.org>
cc:	Matthew Garrett <mjg59@...f.ucam.org>,
	Manoj Iyer <manoj.iyer@...onical.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"Herrmann3, Andreas" <Andreas.Herrmann3@....com>
Subject: Re: [PATCH] Quirk to fix suspend/resume on Lenovo Edge 11,13,14,15

On Thu, 13 Jan 2011, Borislav Petkov wrote:
> On Thu, Jan 13, 2011 at 04:30:43PM -0500, Thomas Gleixner wrote:
> > The more interesting info is there in Manoj's logs:
> > 
> > [    0.036455] ..TIMER: vector=0x30 apic1=0 pin1=0 apic2=-1 pin2=-1
> > [    0.040000] ..MP-BIOS bug: 8254 timer not connected to IO-APIC
> > [    0.040000] ...trying to set up timer (IRQ0) through the 8259A ...
> > [    0.040000] ..... (found apic 0 pin 0) ...
> > [    0.080021] ....... works.
> > 
> > versus
> > 
> > [    0.036460] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
> > 
> > So the "working" state is using "apic 0 pin 0" while the non working
> > state is using "vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1".
> > 
> > Something changes across suspend/resume which makes the BIOS
> > advertised routing work with PIT but not with HPET. Further why does
> > the apic 0/0 solution found by the kernel (when ignoring BIOS) works
> > always (except that we don't know whether the "nohpet" case works as
> > well, but I bet it does).
> 
> Yes, it does. With "nohpet" we use PIT and PIT obviously works.

No. We have no prove that acpi_skip_timer_override and nohpet work
together :)

> > So we are back to the question I raised above: What changes and even
> > more interesting what changes after the HPET expires - which we know
> > for sure that it must happen as otherwise we wont get a HPET interrupt
> > after the 32bit wraparound.
> > 
> > We need answers to these questions before applying any
> > patch/workaround/quirk or whatever.
> 
> Well, this is easily answered in the theoretical sense, without the
> actual details :):
> 
> 1. HPET gets reinitialized first
> 2. Something programs it
> 3. Timer expires but timer IRQ routing is still wrong and "Something"
>    doesn't get its IRQ.
> 4. Timer IRQ routing gets "fixed" as part of the resume path.
> 
> ... we end up waiting for the counter to wraparound and get an IRQ which
> gets delivered this time.
> 
> Does that make sense at all?

Yes, that's what I figured, but we need some explanation WHY this is
"working" magically. Once we have that we can fix the issue at hand
w/o applying random quirks.

Thanks,

	tglx
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