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: Wed, 13 Feb 2013 16:04:06 -0600 Message-ID: <20130213220406.GJ22867@thinkpad-t410> References: <1360599681-24781-1-git-send-email-seth.forshee@canonical.com> <20130211175213.GA25139@srcf.ucam.org> <20130211190617.GH13768@thinkpad-t410> <20130211190914.GA27364@srcf.ucam.org> <20130213203228.GE22867@thinkpad-t410> <20130213205558.GA16559@srcf.ucam.org> <20130213214654.GG22867@thinkpad-t410> <20130213215435.GA17831@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from youngberry.canonical.com ([91.189.89.112]:56926 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752157Ab3BMWEL (ORCPT ); Wed, 13 Feb 2013 17:04:11 -0500 Content-Disposition: inline In-Reply-To: <20130213215435.GA17831@srcf.ucam.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Garrett Cc: Len Brown , "Rafael J. Wysocki" , linux-acpi@vger.kernel.org, Ben Jencks , joeyli On Wed, Feb 13, 2013 at 09:54:35PM +0000, Matthew Garrett wrote: > On Wed, Feb 13, 2013 at 03:46:54PM -0600, Seth Forshee wrote: > > > After every brightness change? Maybe it would be better to just test for > > this during initialization, then set device->cap._BQC to 0 so we won't > > use it. > > That would require us to change the backlight during boot, which we > don't necessarily want to do. There's also the risk that if we only do > the check once it'll correspond to a valid value and we'll get a false > positive. We're already setting the level during boot to check whether or not _BQC returns brightness values or indexes. We'd obviously have to try several values to be fairly certain that this bug wasn't present.