From mboxrd@z Thu Jan 1 00:00:00 1970 From: yakui_zhao Subject: Re: [RFC] [intel-gfx] :The backlight issue when KMS is used Date: Wed, 08 Apr 2009 08:59:55 +0800 Message-ID: <1239152395.3635.13.camel@localhost.localdomain> References: <1238737778.3582.163.camel@localhost.localdomain> <20090403092408.66809996@hobbes> <20090403162906.GB23243@srcf.ucam.org> <1239075911.3582.206.camel@localhost.localdomain> <20090407055717.GA14710@srcf.ucam.org> <1239089123.3582.228.camel@localhost.localdomain> <1239092434.7661.87.camel@rzhang-dt> <20090407082256.GA17012@srcf.ucam.org> <1239094102.7661.103.camel@rzhang-dt> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com ([192.55.52.93]:55806 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752438AbZDHA6r (ORCPT ); Tue, 7 Apr 2009 20:58:47 -0400 In-Reply-To: <1239094102.7661.103.camel@rzhang-dt> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Zhang, Rui" Cc: Matthew Garrett , Jesse Barnes , "intel-gfx@lists.freedesktop.org" , "dri-devel@lists.sourceforge.net" , "sonne@debian.org" , "rpurdie@linux.intel.com" , Thomas Renninger , Len Brown , linux-acpi On Tue, 2009-04-07 at 16:48 +0800, Zhang, Rui wrote: > CC Thomas, Len and linux-acpi mail list. > > On Tue, 2009-04-07 at 16:22 +0800, Matthew Garrett wrote: > > On Tue, Apr 07, 2009 at 04:20:34PM +0800, Zhang Rui wrote: > > > > > All subsystems can register a set of callbacks for backlight control in > > > its own way, e.g. ACPI, platform driver, i915. > > > And the backlight manager only exports one single I/F to users, like: > > > ----| > > > |----brightness > > > |----actual_brightness > > > |----max_brightness > > > |----... > > > |----mode > > > and it supports multiple modes, e.g. > > > 1. generic ---ACPI > > > 2. platform---platform drivers > > > 3. legacy-----i915 > > > > This seems to be a lot of complexity for an uncommon case. Is there any > > real need to modify the mode at runtime? > > if this is implemented, the video_detect.c can be removed because we > don't need to detect the ACPI video extension when loading platform > drivers. > every driver that has its own ways to control the backlight can register > a set of callbacks and then it's the backlight manager's responsibility > to choose which one to use. > > > What happens if the platform > > driver gets loaded before i915? > > > the backlight manager always choose the one with the highest priority if > multiple callbacks are registered. i.e > if (ACPI control methods are available) > changes to the "generic" mode > else if (platform specific callbacks are available) > changes to the "platform" mode > else if (i915 callbacks are available) > changes to the "legacy" mode > > the backlight manager always run this logic when a new set of callbacks > is registered/unregistered. Is this manager realized in kernel space or user space? > > thanks, > rui