From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: Re: [PATCH] ACPI: disable the ACPI backlight control on laptops with buggy _BCL methods Date: Fri, 9 Jan 2009 01:18:09 +0000 Message-ID: <20090109011809.GA23213@srcf.ucam.org> References: <1231383496.20746.44.camel@rzhang-dt> <20090108033250.GA2550@srcf.ucam.org> <1231396321.20746.79.camel@rzhang-dt> <20090108124342.GA10458@srcf.ucam.org> <1231463618.20746.93.camel@rzhang-dt> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from cavan.codon.org.uk ([93.93.128.6]:55880 "EHLO vavatch.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758747AbZAIBSP (ORCPT ); Thu, 8 Jan 2009 20:18:15 -0500 Content-Disposition: inline In-Reply-To: <1231463618.20746.93.camel@rzhang-dt> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Zhang Rui Cc: Len Brown , linux-acpi , "trenn@suse.de" On Fri, Jan 09, 2009 at 09:13:38AM +0800, Zhang Rui wrote: > > _BQC returns 3 when the actual backlight level is 0x50. > We only know that the value returned by _BQC is invalid but we never > know the value is an index until we see the _AML code. If the value returned is less than the smallest value in the _BLC block, then it's an index. This heuristic will never break a standards compliant system, but (to the best of my knowledge) will work with any of these systems that we're currently aware of. -- Matthew Garrett | mjg59@srcf.ucam.org