linux-kernel - Re: [PATCH v3] Enable A20 using KBC for some MSI laptops to fix S3 resume

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Message-Id: <201212111959.15808.linux@rainbow-software.org>
Date:	Tue, 11 Dec 2012 19:59:15 +0100
From:	Ondrej Zary <linux@...nbow-software.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Alan Cox <alan@...rguk.ukuu.org.uk>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] Enable A20 using KBC for some MSI laptops to fix S3 resume

On Monday 10 December 2012 22:26:18 H. Peter Anvin wrote:
> On 11/05/2012 12:35 PM, Ondrej Zary wrote:
> > On Friday 26 October 2012 10:56:44 Ondrej Zary wrote:
> >> Some MSI laptop BIOSes are broken - INT 15h code uses port 92h to enable
> >> A20 line but resume code assumes that KBC was used.
> >> The laptop will not resume from S3 otherwise but powers off after a
> >> while and then powers on again stuck with a blank screen.
> >>
> >> Fix it by enabling A20 using KBC. Affected laptop list and DMI data are
> >> from bug reports at Ubuntu Launchpad.
> >>
> >> Also add kernel parameter to easily activate this quirk on any system.
> >>
> >> Only compile tested. The original patch was tested with EX600 and PR200.
> >>
> >> Fixes https://bugzilla.kernel.org/show_bug.cgi?id=12878
> >
> > The bug was marked as RESOLVED CODE_FIX but I wonder what happened to
> > this patch. Was it applied? Or is someone working on a better way to fix
> > this problem?
>
> Sorry, I managed to forget about this.
>
> Is there any way you could test this patch by any chance?

I've just tested the patch and it does not work (no change in behavior).

> I would be a lot happier if this works as a general solution rather than
> relying on a quirk...

As I said before, the BIOS probably breaks on resume before any Linux code is 
executed. So any fix must be done before suspending.

I hate quirks too. A general solution would be to always enable A20 using KBC 
(if KBC is present) but that's probably not acceptable.


-- 
Ondrej Zary
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