From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH] ACPI: Disable Windows 8 compatibility for some Lenovo ThinkPads Date: Mon, 11 Feb 2013 20:31:08 +0100 Message-ID: <12728315.LFW3i1ALOK@vostro.rjw.lan> References: <1360599681-24781-1-git-send-email-seth.forshee@canonical.com> <20130211190617.GH13768@thinkpad-t410> <20130211190914.GA27364@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7Bit Return-path: Received: from hydra.sisk.pl ([212.160.235.94]:37248 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759236Ab3BKTYn (ORCPT ); Mon, 11 Feb 2013 14:24:43 -0500 In-Reply-To: <20130211190914.GA27364@srcf.ucam.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Garrett , Seth Forshee Cc: Len Brown , linux-acpi@vger.kernel.org, Ben Jencks , joeyli , Zhang Rui On Monday, February 11, 2013 07:09:14 PM Matthew Garrett wrote: > On Mon, Feb 11, 2013 at 01:06:17PM -0600, Seth Forshee wrote: > > On Mon, Feb 11, 2013 at 05:52:13PM +0000, Matthew Garrett wrote: > > > So the problem is that userspace is writing values that don't happen to > > > be aligned with the values the hardware reacts to, and so nothing gets > > > changed? > > > > Yes. The values are valid according to to _BCL, but _BCM is discarding > > any values that aren't contained in an array named BRTW. BRTW is > > literally the object returned by _BCL returns for !Windows 2012. Here's > > a link to the AML if you'd like to take a look. > > Right. My concern here is that Windows clearly doesn't trigger the > issue, and so there's some chance that we'll see similar issues on other > machines. Disabling Windows 8 compatibility isn't really an option. One > choice might be to have the ACPI video driver set all intermediate > values if the system makes the Windows 8 OSI call? At least I'd prefer that, so it would be great to verify if it works. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.