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 12:53:17 +0100 Message-ID: <20080710115317.GA7013@srcf.ucam.org> References: <200807031809.03172.trenn@suse.de> <200807101315.21904.trenn@suse.de> <20080710111900.GA6303@srcf.ucam.org> <200807101336.08035.trenn@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <200807101336.08035.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 01:36:04PM +0200, Thomas Renninger wrote: > On Thursday 10 July 2008 13:19:00 Matthew Garrett wrote: > > No, I said that on Thinkpads with a PWM method, the PWM method has to be > > called in order to avoid the delay. There's no need for a blacklist. > > Ok. > I just got a report that Dells must not use the video driver: > https://bugzilla.novell.com/show_bug.cgi?id=404627 > > They have a really ugly dcdbas driver which issues SMIs triggered from > userspace. If the ACPI video driver has bound, then using the dcdbas mechanism for backlight control is incorrect. I wasn't aware that any Dells actually implemented that. The correct thing is for userspace to stop using dcdbas if a real backlight control is available, not to cripple the ACPI video driver. -- Matthew Garrett | mjg59@srcf.ucam.org