From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Subject: Re: [REGRESSION BISECTED] backlight control stops workin with 3.14 and later Date: Wed, 13 Aug 2014 16:43:08 +0300 Message-ID: <87d2c4qzdf.fsf@intel.com> References: <53CE07D9.3090308@redhat.com> <53CF7651.4080305@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTP id 790ED6E093 for ; Wed, 13 Aug 2014 06:45:18 -0700 (PDT) In-Reply-To: <53CF7651.4080305@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Hans de Goede , Daniel Vetter Cc: "intel-gfx@lists.freedesktop.org" , Bertrik Sikken List-Id: intel-gfx@lists.freedesktop.org On Wed, 23 Jul 2014, Hans de Goede wrote: > Hi, > > On 07/22/2014 08:52 AM, Daniel Vetter wrote: >> On Tue, Jul 22, 2014 at 8:42 AM, Hans de Goede wrote: >>> Hi Jani et al, >>> >>> A friend of mine Bertrik Sikken (in the Cc) his backlight control >>> stopped working for him on his Samsung N150Plus netbook. >>> >>> I took a quick look, and the raw intel_backlight backlight interface >>> works under 3.14, but the firmware samsung_laptop backlight interface, >>> which is what most userspace apps will use by default, stops working >>> in 3.14 . >>> >>> I've asked him to bisect this and the bisect points out this >>> commit as the culprit: >>> >>> b35684b8fa94e04f55fd38bf672b737741d2f9e2 is the first bad commit >>> commit b35684b8fa94e04f55fd38bf672b737741d2f9e2 >>> Author: Jani Nikula >>> Date: Thu Nov 14 12:13:41 2013 +0200 >>> >>> drm/i915: do full backlight setup at enable time >>> >>> We should now have all the information we need to do a full >>> initialization of the backlight registers. >>> >>> v2: Keep QUIRK_NO_PCH_PWM_ENABLE for now (Imre). >>> >>> Signed-off-by: Jani Nikula >>> Reviewed-by: Imre Deak >>> Signed-off-by: Daniel Vetter >>> >>> Note that this laptop has an acpi_video backlight interface too, >>> but that has been broken from the start and gets disabled by >>> samsung-laptop based on dmi matching. >> >> How does the intel backlight fare? > > That works fine with 3.14 . > >> Please test both 3.14 and 3.15 and > > We've tested with 3.14, please let us know if you also want > Bertrik to test with 3.15. > >> also test what happens when you blacklist the samsung-laptop driver >> (if that's possible without wreaking the machine). > > Then the vendor interface won't get promoted, acpi-video will load, > and things likely will not work. > > Bertrik, can you try blacklisting the samsung-laptop module, then > check /sys/class/backlight, the samsung_laptop dir should be gone > replaced by an acpi_video0 (or some such) dir. Please try if that > works. If that does not work, try booting with both the module > blacklisted and "acpi_backlight=vendor" on the kernel commandline, > then you should see only the intel-backlight under /sys/class/backlight > and things should work. > >> Also please grab latest intel-gpu-tools and record a register dump >> with intel_reg_dump, again for both broken and working kernels. > > Bertrik, can you do this please (without the blacklisting or special > kernel commandline options). Please attach dmesg with drm.debug=0xe module parameter set for some recent kernel. BR, Jani. > > Regards, > > Hans -- Jani Nikula, Intel Open Source Technology Center