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: Thu, 8 Jan 2009 03:32:50 +0000 Message-ID: <20090108033250.GA2550@srcf.ucam.org> References: <1231383496.20746.44.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]:39625 "EHLO vavatch.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752078AbZAHDc6 (ORCPT ); Wed, 7 Jan 2009 22:32:58 -0500 Content-Disposition: inline In-Reply-To: <1231383496.20746.44.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 Thu, Jan 08, 2009 at 10:58:16AM +0800, Zhang Rui wrote: > Some users used to control the backlight via the platform interface. > But commit c3d6de698c84efdbdd3781b7058bcc339ab43da8 disables the platform > backlight control if ACPI video backlight control is available. > > This breaks the laptops with buggy _BCL/_BCM/_BQC methods. i.e. only ACPI > backlight I/F are available on these laptops but they don't work. > > With this patch applied, the ACPI backlight control are disabled instead > on these laptops. Why? These all seem to behave consistently, so I can't see any problem with us simply adding support for this varient. Disabling the ACPI control when we have no idea whether there's a platform driver available for the machine doesn't seem like the right fix. -- Matthew Garrett | mjg59@srcf.ucam.org