From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: Re: [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A Date: Wed, 31 Jul 2013 18:52:32 +0100 Message-ID: <20130731175232.GA29987@srcf.ucam.org> References: <1375125658-1223-1-git-send-email-felipe.contreras@gmail.com> <3453253.oZLO1ChPbL@vostro.rjw.lan> <37178266.QXgbv9rq0i@vostro.rjw.lan> <20130731051421.GA15766@srcf.ucam.org> <20130731140010.GA24560@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from cavan.codon.org.uk ([93.93.128.6]:41659 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751351Ab3GaRwg (ORCPT ); Wed, 31 Jul 2013 13:52:36 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Felipe Contreras Cc: "Rafael J. Wysocki" , Aaron Lu , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, Len Brown , Linus Torvalds On Wed, Jul 31, 2013 at 12:46:04PM -0500, Felipe Contreras wrote: > That doesn't change the fact that you were wrong, and there *is* > actually a way. The fact that you don't want to go there doesn't mean > it's not there. A quirk list will be incomplete, and as such there's no way to guarantee whether or not a value of 0 will turn off the backlight. This is why the interface doesn't make that guarantee, and why any userspace that depends upon that behaviour is behaving incorrectly. > Here's another: device tree. There's no functional distinction between device tree and a quirk list on x86 - they're both static data sources provided by something other than the system firmware. As a result, they will both be incomplete. > There are ways to provide a consistent backlight interface to user-space. No, there aren't. What you *can* do is propose to change the ABI description for the sysfs backlight interface such that any system where 0 turns off the backlight is considered buggy, but that won't make those systems vanish. A good interface doesn't promise things it can't guarantee, so I'd expect that any such proposal would be rejected. -- Matthew Garrett | mjg59@srcf.ucam.org