linux-kernel - Re: [PATCH] samsung-laptop: unregister ACPI video module for some well known laptops

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Message-ID: <CAHR064hBVJjmEd=GeGuG-xTg5ONfJTxwqzP88=JABaXFrfiehA@mail.gmail.com>
Date:	Fri, 6 Apr 2012 11:42:18 +0200
From:	Corentin Chary <corentin.chary@...il.com>
To:	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux acpi <linux-acpi@...r.kernel.org>,
	Len Brown <len.brown@...el.com>
Subject: Re: [PATCH] samsung-laptop: unregister ACPI video module for some
 well known laptops

On Tue, Mar 27, 2012 at 1:21 PM, Matthew Garrett <mjg59@...f.ucam.org> wrote:
> On Tue, Mar 27, 2012 at 11:11:18AM +0200, Corentin Chary wrote:
>> Matthew, is this one ok ? I really hope this patch can go in 3.4 so we
>> don't introduce a regression for old laptops.
>
> Yes, I've got this now.
>
> Thanks,

A user just found a DSDT which is broken by this way of doing things
(this is not really a regression since it was also broken before).

_BCL contains a wierd "Or (VDRV, 0x02, VDRV)".
So if you call _BLC once (video.ko will), it set a flag that affect
the behavior of all backlight related stuff, and it breaks
samsung-laptop's backlight even if samsung-laptop unload the acpi
backlight.
Using acpi_backlight=vendor solves that since it prevents the module
from being loaded. My previous patch also fix that since it use
acpi_backlight= mechanism.

Do you think using acpi_backlight=vendor is a good enought solution
here ? Should we use my first patch instead ?

-- 
Corentin Chary
http://xf.iksaif.net

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