Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759616Ab3GaLcx (ORCPT ); Wed, 31 Jul 2013 07:32:53 -0400 Received: from mail-la0-f54.google.com ([209.85.215.54]:55971 "EHLO mail-la0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756407Ab3GaLcu (ORCPT ); Wed, 31 Jul 2013 07:32:50 -0400 MIME-Version: 1.0 In-Reply-To: <20130731051421.GA15766@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> Date: Wed, 31 Jul 2013 06:32:47 -0500 Message-ID: Subject: Re: [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A From: Felipe Contreras To: Matthew Garrett Cc: "Rafael J. Wysocki" , Aaron Lu , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, Len Brown , Linus Torvalds Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 955 Lines: 25 On Wed, Jul 31, 2013 at 12:14 AM, Matthew Garrett wrote: > On Tue, Jul 30, 2013 at 07:11:06PM -0500, Felipe Contreras wrote: > >> No, the ACPI driver is exposing a backlight interface, which has a >> defined stable API. > > From the ACPI spec: > > 'The OEM may define the number 0 as "Zero brightness" that can mean to > turn off the lighting (e.g. LCD panel backlight) in the device.' > > There's no mechanism for an OS to know whether or not a firmware > implementation will actually turn the backlight off at 0, so there's no > way the OS can define the lowest backlight state as anything other than > "May or may not turn the screen off". Yes there is; quirks. -- Felipe Contreras -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/