From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: Re: [PATCH 2/2] ACPI Check for backlight support via ACPI video.ko otherwise use vendor ACPI drivers Date: Thu, 10 Jul 2008 13:58:44 +0100 Message-ID: <20080710125844.GB8561@srcf.ucam.org> References: <200807031809.03172.trenn@suse.de> <200807101419.08524.trenn@suse.de> <20080710122454.GA7584@srcf.ucam.org> <200807101448.16662.trenn@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <200807101448.16662.trenn@suse.de> Sender: linux-acpi-owner@vger.kernel.org To: Thomas Renninger Cc: ak@linux.intel.com, linux-acpi@vger.kernel.org, Henrique de Moraes Holschuh , Carlos Corbacho , Jonathan Woithe , malattia@linux.it, stelian@popies.net, linux-next@vger.kernel.org, Corentin CHARY , Lennart Poettering , Julia Jomantaite , corsac@debian.org, dannybaumann@web.de, marcus@better.se, Zhang Rui List-Id: linux-next.vger.kernel.org On Thu, Jul 10, 2008 at 02:48:12PM +0200, Thomas Renninger wrote: > On Thursday 10 July 2008 14:24:54 Matthew Garrett wrote: > > On Thu, Jul 10, 2008 at 02:19:04PM +0200, Thomas Renninger wrote: > > > Yes, I agree. > > > Anyway, given the fact that video.ko was rather broken all the time, a > > > reasonable solution for now is to exclude Dells from using it. > > > > No, the problem was that the backlight was simultaneously being altered > > by two pieces of code. kpowersave is doing the backlight control via hal > > (I assume), and hal should simply not provide the Dell backlight control > > on systems that have ACPI video backlight control. There's no need to > > have this policy in the kernel. > Do you know Dells working with the video.ko driver? Presumably the Inspiron 640M, since otherwise there's no way that that bug could trigger. > If you tell me video.ko, best with an IGD device and without one is working > there, it can be removed. Even then talking with dcdbas developers how to > inform their user space app first is a good idea. The userspace app that needs fixing is hal. I'm already working on that. > As Dell is cooking their own soup here and the dcdbas driver was reported to > work correctly with ACPI brightness functions in BIOS it is ok to blacklist > Dells here until the first test reports are coming in telling us that > video.ko is actually working correctly there. > Testing will be easy via boot param. No, really, let's just fix the problem properly. > I will not risk again that this whole bunch of our patches will be reverted > on -rc6 again, because a Dell user is reporting a backlight regression. > We then have the same situation we had when the "check for physical device was > removed": The implementation is wrong but worked. The implementation is > right, but does not work on a specific machine -> regression -> revert. I've no idea at all why you think this is a kernel issue. -- Matthew Garrett | mjg59@srcf.ucam.org