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

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Date:	Mon, 31 Jan 2011 10:44:19 -0600
From:	Manoj Iyer <manoj.iyer@...onical.com>
To:	Andreas Herrmann <andreas.herrmann3@....com>
Cc:	"James C. Georgas" <james.georgas@...oo.ca>,
	Borislav Petkov <bp@...64.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] Quirk to fix suspend/resume on Lenovo Edge 11,13,14,15

Sorry, I was not able to get to this last week, I will test your patch
today and reply by EOBD today.

On Fri, Jan 28, 2011 at 11:59 AM, Andreas Herrmann
<andreas.herrmann3@....com> wrote:
> On Fri, Jan 14, 2011 at 02:55:30PM -0500, Manoj Iyer wrote:
>> Borislav,
>>
>> Any more thoughts on this one ?
>
> Seems that we've identified the root cause.
>
> I wondered why systems with the problem have configured IOAPIC pin
> with polarity=1 (low active).  That was different to what the working
> systems used.
>
> Switching the configuration to the usual polarity=0 (high active)
> fixed the issue.
>
> The explanation is that when hpet interrupt is triggerd, signal goes
> from low to high. (AFAIK HPET spec even mentions that HPET interrupts
> are all active high.)
>
> Now if IO-APIC pin is configured as low active it just ignores this
> signal change. It just triggers later when for next interrupt signal
> will go from high to low and high again. (That happens the first time
> after resume when the HPET counter wrapped around.)
>
> Setting the correct polarity fixes the detection of the first hpet
> interrupt after resume.
>
> To confirm that your systems behave similar you should boot with
> "apic=debug" kernel parameter. The output for IO APIC should show
> polarity=1 for IO APIC pin 2, e.g.
>
>  [    0.158179] IO APIC #2......
>   ...
>  [    0.158205]  NR Dst Mask Trig IRR Pol Stat Dmod Deli Vect:
>  [    0.158210]  00 000 1    0    0   0   0    0    0    00
>  [    0.158217]  01 003 0    0    0   0   0    1    1    31
>  [    0.158224]  02 003 0    0    0   1   0    1    1    30
>
> Furthermore you can check with attached test patch whether changing
> the polarity fixes the problem on your system. IO APIC debug output
> with this patch should change to
>
>  [    0.156170] IO APIC #2......
>   ...
>  [    0.156197]  NR Dst Mask Trig IRR Pol Stat Dmod Deli Vect:
>  [    0.156202]  00 000 1    0    0   0   0    0    0    00
>  [    0.156209]  01 003 0    0    0   0   0    1    1    31
>  [    0.156216]  02 003 0    0    0   0   0    1    1    30
>
>
> I'll come up with an SB800 quirk asap. (Of course we'll also try to
> fix the respective BIOSes but too often BIOS updates are only
> available for a limited time period.)
>
>
> Regards,
>
> Andreas
>
> --
> Operating | Advanced Micro Devices GmbH
>  System  | Einsteinring 24, 85609 Dornach b. München, Germany
>  Research | Geschäftsführer: Alberto Bozzo, Andrew Bowd
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>



-- 
-----------------------------------------------------
Manoj Iyer
Ubuntu/Canonical Kernel Developer
Hardware Enablement Team
------------------------------------------------------
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