From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Subject: Re: Linux 3.11-rc2 [backlight] [ASUS N56VZ] Date: Thu, 25 Jul 2013 11:09:27 +0300 Message-ID: <87hafjxdqg.fsf@intel.com> References: <20130724210200.GY5939@phenom.ffwll.local> <6051153.b6TE1dlrel@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by gabe.freedesktop.org (Postfix) with ESMTP id 59EF1E5DCD for ; Thu, 25 Jul 2013 01:07:59 -0700 (PDT) In-Reply-To: <6051153.b6TE1dlrel@vostro.rjw.lan> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: "Rafael J. Wysocki" , Linus Torvalds Cc: Aaron Lu , Matthew Garrett , * =?utf-8?Q?SAM=C3=8D?= * , intel-gfx , LKML , ACPI Devel Maling List , Igor Gnatenko List-Id: intel-gfx@lists.freedesktop.org On Thu, 25 Jul 2013, "Rafael J. Wysocki" wrote: > On Wednesday, July 24, 2013 02:05:15 PM Linus Torvalds wrote: >> On Wed, Jul 24, 2013 at 2:02 PM, Daniel Vetter wrote: >> > >> > I think a i915 module option should be doable, otoh people seem to have a >> > viable workaround by setting a different acpi os version already. >> >> At least the original claim was that if you set a non-windows8 acpi os >> version, you hit other bugs.. >> >> But yeah, if we just do a plain revert, that may be the only option >> for the people for whom the current (to-be-reverted) patches made >> things work. > > Well, I wonder what about the appended (untested) patch? Rafael, before going there, I've been trying to wrap my (poor, rusty after vacation) head around commit 8c5bd7adb2ce47e6aa39d17b2375f69b0c0aa255 Author: Rafael J. Wysocki Date: Thu Jul 18 02:08:06 2013 +0200 ACPI / video / i915: No ACPI backlight if firmware expects Windows 8 and I can't see how it could work. First, the ACPI_VIDEO_SKIP_BACKLIGHT flag seems to be checked before it's actually set anywhere. Buried deep in the calls from acpi_video_bus_add(), acpi_video_verify_backlight_support() is used before acpi_video_backlight_quirks() gets called. (Perhaps if i915 is reloaded, this goes right as the flags are already set.) Second, with i915 that has opregion support, __acpi_video_register() should only ever get called once. Which means the acpi_walk_namespace() with video_unregister_backlight() should never get called in register. Please enlighten me. BR, Jani. -- Jani Nikula, Intel Open Source Technology Center