From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bertrik Sikken Subject: Re: [REGRESSION BISECTED] backlight control stops workin with 3.14 and later Date: Thu, 21 Aug 2014 23:44:41 +0200 Message-ID: <53F66849.4010608@sikken.nl> References: <53CE07D9.3090308@redhat.com> <53CF7651.4080305@redhat.com> <87d2c4qzdf.fsf@intel.com> <53ED11DD.3040104@sikken.nl> <878umpq36f.fsf@intel.com> <53F06B65.4090001@sikken.nl> <87wqa6nt91.fsf@intel.com> <7955720e6579951f4da64388ab4e1673.squirrel@webmail1.one.com> <87iolohakj.fsf@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from smtp3.versatel.nl (smtp3.versatel.nl [62.58.50.90]) by gabe.freedesktop.org (Postfix) with ESMTP id BAEE56E2A8 for ; Thu, 21 Aug 2014 14:44:38 -0700 (PDT) In-Reply-To: <87iolohakj.fsf@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Jani Nikula Cc: "intel-gfx@lists.freedesktop.org" List-Id: intel-gfx@lists.freedesktop.org On 19-8-2014 3:29, Jani Nikula wrote: > On Tue, 19 Aug 2014, Bertrik Sikken wrote: >>> On Sun, 17 Aug 2014, Bertrik Sikken wrote: >>>> On 15-8-2014 3:43, Jani Nikula wrote: >>>>> On Thu, 14 Aug 2014, Bertrik Sikken wrote: >>>> >>>>>> Attached is dmesg output from booting kernel 3.14-2 (debian unstable) >>>>>> with drm.debug=0xe and the samsung_laptop module enabled, from my >>>>>> Samsung N150plus netbook. >>>>> >>>>> Have you tried 3.15? >>>> >>>> I've built the v3.15 kernel (using the .config file from debian >>>> unstable and doing make oldconfig). >>>> >>>> The backlight is at maximum brightness after boot and I can't control >>>> it using the backlight buttons, nor by writing to >>>> /sys/class/backlight/samsung/brightness >>>> (say half the value or 1/10th of max_brightness) >>>> >>>> Backlight does work when writing >>>> /sys/class/backlight/intel_backlight/brightness >>> >>> How about disabling samsung backlight module with 3.15? >> >> I'm not sure what you mean by that. >> >> As I understand it, there are three ways to control the backlight on this >> netbook: using intel_backlight, samsung_laptop (using a "sabi" interface) >> and acpi_video. >> Backlight control using the samsung_laptop driver no longer seems to work >> after the change. If I disable it (e.g. by blacklisting it), I expect it >> to no longer work at all obviously. >> >> What do you want me to test exactly? > > If the intel_backlight interface works in 3.15, I presume the problem is > that you have a non-functional samsung backlight interface that is > preferred over intel_backlight by your userspace. I tested the intel_backlight interface in linux v3.15 with the samsung backlight module blacklisted. The intel_backlight interface still works. Regards, Bertrik