Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753200Ab3IQNEq (ORCPT ); Tue, 17 Sep 2013 09:04:46 -0400 Received: from mail-la0-f41.google.com ([209.85.215.41]:48236 "EHLO mail-la0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753162Ab3IQNEo (ORCPT ); Tue, 17 Sep 2013 09:04:44 -0400 Message-ID: <1379423079.2218.2.camel@ThinkPad-X230.localdomain> Subject: Re: [PATCH v2 3/3] ACPI / video: Do not register backlight if win8 and native interface exists From: Igor Gnatenko To: Aaron Lu Cc: linux-acpi@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Daniel Vetter , "Rafael J. Wysocki" , Matthew Garrett , Seth Forshee , Lee Chun-Yi , Richard Purdie , Yves-Alexis Perez , Felipe Contreras , Henrique de Moraes Holschuh , Jani Nikula Date: Tue, 17 Sep 2013 17:04:39 +0400 In-Reply-To: <1379409796-29350-4-git-send-email-aaron.lu@intel.com> References: <1379409796-29350-1-git-send-email-aaron.lu@intel.com> <1379409796-29350-4-git-send-email-aaron.lu@intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.9.91 (3.9.91-2.fc20) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1564 Lines: 35 On Tue, 2013-09-17 at 17:23 +0800, Aaron Lu wrote: > According to Matthew Garrett, "Windows 8 leaves backlight control up > to individual graphics drivers rather than making ACPI calls itself. > There's plenty of evidence to suggest that the Intel driver for > Windows 8 doesn't use the ACPI interface, including the fact that > it's broken on a bunch of machines when the OS claims to support > Windows 8. The simplest thing to do appears to be to disable the > ACPI backlight interface on these systems". > > So for Win8 systems, if there is native backlight control interface > registered by GPU driver, ACPI video will not register its own. For > users who prefer to keep ACPI video's backlight interface, the existing > kernel cmdline option acpi_backlight=video can be used. > > This patch is an evolution from previous work done by Matthew Garrett, > Chun-Yi Lee, Seth Forshee and Rafael J. Wysocki. > > Signed-off-by: Aaron Lu Tested-by: Igor Gnatenko > --- > drivers/acpi/internal.h | 5 ++--- > drivers/acpi/video.c | 27 +++++---------------------- > drivers/acpi/video_detect.c | 14 ++++++++++++-- > 3 files changed, 19 insertions(+), 27 deletions(-) -- Igor Gnatenko Fedora release 20 (Heisenbug) Linux 3.12.0-0.rc1.git0.1.fc20.x86_64 -- 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/