Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751640Ab3FYQKi (ORCPT ); Tue, 25 Jun 2013 12:10:38 -0400 Received: from mail-ie0-f174.google.com ([209.85.223.174]:36515 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750971Ab3FYQKg (ORCPT ); Tue, 25 Jun 2013 12:10:36 -0400 MIME-Version: 1.0 X-Originating-IP: [178.83.130.250] In-Reply-To: <20130625160848.GA27123@srcf.ucam.org> References: <1370818899-8595-1-git-send-email-matthew.garrett@nebula.com> <1371937599.17761.19.camel@scapa> <20130625160848.GA27123@srcf.ucam.org> Date: Tue, 25 Jun 2013 18:10:35 +0200 Message-ID: Subject: Re: [PATCH 0/3] Fix backlight issues on some Windows 8 systems From: Daniel Vetter To: Matthew Garrett Cc: Yves-Alexis Perez , linux-acpi@vger.kernel.org, seth.forshee@canonical.com, joeyli.kernel@gmail.com, intel-gfx , dri-devel , Linux Kernel Mailing List , Len Brown , "Rafael J. Wysocki" , Henrique de Moraes Holschuh Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1722 Lines: 35 On Tue, Jun 25, 2013 at 6:08 PM, Matthew Garrett wrote: > On Sat, Jun 22, 2013 at 11:46:39PM +0200, Yves-Alexis Perez wrote: > >> Before Linux support for acpi_osi("Windows 2012") (and when booting with >> acpi_osi="!Windows 2012"), brightness keys were handled by the kernel >> just fine, whether in console, in the display manager or in my desktop >> environment (Xfce). xfce4-power-manager just needs to be told that the >> brightness keys are already handled and it doesn't need to do anything. > > Right, the kernel has special-casing to hook the backlight keys up to > the ACPI backlight control. This is an awful thing, because there's no > way to detect this case other than parsing a single driver-specific > module parameter. > > Could this functionality be duplicated across other backlight drivers? > Not easily. The ACPI driver receives keypresses and performs backlight > control. The i915 driver doesn't receive keypresses. We could easily tie > certain keycodes into backlight events, but which backlight should they > control? You're really starting to get into the kind of complex policy > decision that's best left to userspace, which is where it should have > been to begin with. Do we have any chances to amend this mistake by (gradually) phasing out support for the direct keypress forwarding in ACPI? Or at least some plans? -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- 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/