From mboxrd@z Thu Jan  1 00:00:00 1970
From: Seth Forshee <seth.forshee@canonical.com>
Subject: Re: [PATCH] ACPI: Disable Windows 8 compatibility for some Lenovo
 ThinkPads
Date: Mon, 22 Apr 2013 08:56:51 -0500
Message-ID: <20130422135651.GB31365@thinkpad-t410>
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To: Aaron Lu <aaron.lu@intel.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, Ben Jencks <ben@bjencks.net>, Len Brown <lenb@kernel.org>, linux-acpi@vger.kernel.org, joeyli <jlee@suse.com>, Matthew Garrett <mjg59@srcf.ucam.org>

On Mon, Apr 22, 2013 at 09:40:00PM +0800, Aaron Lu wrote:
> On 04/22/2013 09:06 PM, Seth Forshee wrote:
> >On Mon, Apr 22, 2013 at 08:11:17PM +0800, Aaron Lu wrote:
> >>On 04/22/2013 07:51 PM, Rafael J. Wysocki wrote:
> >>>I suppose we need to blacklist them to start with.  I wouldn't like to apply
> >>>any general changes before we know how many different systems are affected by
> >>>this particular issue.
> >>
> >>I totally agree.
> >
> >Are you sure that all of these machines have an alternate interface for
> >userspace to change the brightness? I know that I've got a non-Lenovo
> >machine with nVidia graphics for which nouveau exposes no backlight
> 
> What's the problem with this system then? The same as the thinkpads in
> bug 51231?

There's no problem with that system; it has another working backlight
interface. I'm only mentioning it to demonstrate that taking away the
ACPI interface could leave some machines without any backlight control
mechanism that Linux currently supports.

Seth