From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seth Forshee Subject: Re: [PATCH] ACPI: Disable Windows 8 compatibility for some Lenovo ThinkPads Date: Mon, 22 Apr 2013 10:11:25 -0500 Message-ID: <20130422151125.GD31365@thinkpad-t410> References: <1360599681-24781-1-git-send-email-seth.forshee@canonical.com> <9174410.cA7eiWOPcn@vostro.rjw.lan> <5175055F.9000600@intel.com> <1587525.URWXxEIA21@vostro.rjw.lan> <517528E5.7030105@intel.com> <20130422130600.GA31365@thinkpad-t410> <51753DB0.9010703@intel.com> <20130422135651.GB31365@thinkpad-t410> <51754424.6040203@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from youngberry.canonical.com ([91.189.89.112]:42427 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752739Ab3DVPLh (ORCPT ); Mon, 22 Apr 2013 11:11:37 -0400 Content-Disposition: inline In-Reply-To: <51754424.6040203@intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Aaron Lu Cc: "Rafael J. Wysocki" , Ben Jencks , Len Brown , linux-acpi@vger.kernel.org, joeyli , Matthew Garrett On Mon, Apr 22, 2013 at 10:07:32PM +0800, Aaron Lu wrote: > On 04/22/2013 09:56 PM, Seth Forshee wrote: > >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. > > I think we just need take away the ACPI interface for these known broken > systems for now, that would require: check if we are in win8 mode, if > so, disable acpi video interface for these known broken systems. > > I think video_detect_dmi_table is the proper place to do this. Well, I suppose that's better than what we've got now. I'll post some patches to the bug for testing. Seth