linux-kernel - Re: [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A

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Date:	Mon, 29 Jul 2013 22:47:26 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Felipe Contreras <felipe.contreras@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	Len Brown <lenb@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A

On Monday, July 29, 2013 03:22:56 PM Felipe Contreras wrote:
> On Mon, Jul 29, 2013 at 3:17 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > On Monday, July 29, 2013 02:20:58 PM Felipe Contreras wrote:
> >> Since v3.7 the acpi backlight driver doesn't work at all on this machine
> >> because presumably the ACPI code contains stub code when Windows 8 OSI is
> >> reported.
> >>
> >> The commit ea45ea7 (in v3.11-rc2) tried to fix this problem by using the intel
> >> backlight driver, however, on this machine it turns the backlight completely
> >> off when it reaches level 0%, after which the user might have a lot trouble
> >> trying to bring it back.
> >>
> >> This patch fixes both regressions by blacklisting the win8 OSI, so we are back
> >> to v3.6 behavior, and it should remain that way until the intel backlight
> >> driver is fixed.
> >
> > Well, it really is a workaround, so perhaps it would be fair to call it this
> > way?
> 
> Maybe, but to me, and to most users, the important thing is that it
> fixes a regression.
> 
> >> Since v3.7, users have been forced to fix the initial regression by modifying
> >> the boot arguments [1].
> >>
> >> [1] https://wiki.archlinux.org/index.php/ASUS_Zenbook_Prime_UX31A
> >>
> >> Signed-off-by: Felipe Contreras <felipe.contreras@...il.com>
> >
> > I don't really feel this is the right approach, but then I don't care enough
> > to fight with you. :-)
> 
> It's not the right approach, I don't think I (or anybody) argued
> otherwise, but unless the Intel driver is fixed before 3.11, it's the
> only sane approach.

Oh, you're *so* sure about that ...

What I'm actually thinking is that applying this workaround will reduce the
incentive to fix intel_backlight for the users in question, so it's not like
there are no drawbacks.

But as I said, I'm not going to fight over this.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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