From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Purdie Subject: Re: [RFC] [intel-gfx] :The backlight issue when KMS is used Date: Wed, 08 Apr 2009 11:50:03 +0100 Message-ID: <1239187803.5339.13.camel@dax.rpnet.com> References: <1238737778.3582.163.camel@localhost.localdomain> <20090407073845.GA15635@srcf.ucam.org> <1239152179.3635.8.camel@localhost.localdomain> <200904081217.15667.trenn@suse.de> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from mga07.intel.com ([143.182.124.22]:24059 "EHLO azsmga101.ch.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751399AbZDHKuI (ORCPT ); Wed, 8 Apr 2009 06:50:08 -0400 In-Reply-To: <200904081217.15667.trenn@suse.de> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Thomas Renninger Cc: yakui_zhao , Matthew Garrett , Jesse Barnes , "intel-gfx@lists.freedesktop.org" , "dri-devel@lists.sourceforge.net" , "sonne@debian.org" , "Zhang, Rui" , Len Brown , linux-acpi On Wed, 2009-04-08 at 12:17 +0200, Thomas Renninger wrote: > Matthew and Jesse are looking for following approach: > Let all drivers try to register for the generic backlight interface. > As we do not know which driver will get loaded first, you want to > detect whether another driver already registered the backlight > interface and implement a priority to eventually let the newly > loaded driver unregister the other driver's backlight device, notify > this driver via a notifier chain and then register the own backlight > interface (is that correct?). > > Priority could look like: > 1) vendor specific drivers > 2) ACPI generic drivers > 3) Graphics card's specific kernel drivers (IGD/Opregion and possibly > others) > 3 has highest prio. > > If I got that right, I do not like: > - the complexity that has to be added to the generic backlight > interface and each backlight driver. I'm not arguing for or against any approach here but if we need to have this priority handoff system, I'd like to see it as a wrapper around the backlight class and the class itself is unlikely to need changes. The wrapper would register one backlight device with the generic class and then redirect the function calls as needed. Cheers, Richard