Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754038Ab2F2OLL (ORCPT ); Fri, 29 Jun 2012 10:11:11 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:38336 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751068Ab2F2OLJ (ORCPT ); Fri, 29 Jun 2012 10:11:09 -0400 Date: Fri, 29 Jun 2012 09:11:00 -0500 From: Seth Forshee To: Corentin Chary Cc: Matthew Garrett , Richard Purdie , linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org Subject: Re: [PATCH] backlight: add support for disabling backlights via sysfs Message-ID: <20120629141100.GB23192@thinkpad-t410> Mail-Followup-To: Corentin Chary , Matthew Garrett , Richard Purdie , linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org References: <1340910426-13269-1-git-send-email-seth.forshee@canonical.com> <20120628191043.GA9777@srcf.ucam.org> <20120628193017.GA29456@thinkpad-t410> <20120628193652.GB10945@srcf.ucam.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1747 Lines: 32 On Fri, Jun 29, 2012 at 02:24:38PM +0200, Corentin Chary wrote: > On Thu, Jun 28, 2012 at 9:36 PM, Matthew Garrett wrote: > > On Thu, Jun 28, 2012 at 02:30:17PM -0500, Seth Forshee wrote: > > > >> I actually don't think Corentin's solution is a bad one. It does suffer > >> from a couple of shortcomings though. First, it only works for broken > >> ACPI backlights, and some platforms have other backlight interfaces that > >> are broken (e.g. the i915 backlight on the MacBook Pro 8,2). Second, > >> marking backlights as broken in the kernel necessitates ever-expanding > >> dmi blacklists in some of the platform drivers, unless we can get > >> vendors to stop providing broken backlight interfaces. > > > > Userspace should already be prioritising platform interfaces over raw > > interfaces, so if gmux works on the Mac then there's no problem. > > Hehe, sometime the platform interface doesn't work and the raw does. > That's the case on various samsung-laptop since we have absolutely no > documentation about SABI and no known way to probe if the > implementation is working or not. But anyway, for samsung-laptop it's > disabled by default in favor of acpi_video (which is also broken most > of the time on samsung laptops). The situation is similar with Toshibas. On some the raw interface is still the only reliable way to change the backlight. I just got my hands on one of these models though, so I'm hoping to make some progress on that front in the near future. -- 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/