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: Wed, 23 Jul 2014 15:15:37 +0200 Message-ID: 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 webmail1.one.com (squirrelmail.public.one.com [195.47.247.29]) by gabe.freedesktop.org (Postfix) with ESMTP id 796926E62D for ; Wed, 23 Jul 2014 06:22:20 -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 Cc: "Nikula, Jani" , "intel-gfx@lists.freedesktop.org" List-Id: intel-gfx@lists.freedesktop.org >> On Tue, Jul 22, 2014 at 8:42 AM, Hans de Goede > 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. With linux kernel v3.14 and the samsung_laptop module blacklisted, I indeed see a /sys/class/backlight/acpi_video0, but changing brightness by writing (as root) to the brightness file does not have an effect. Additionally, with the acpi_backlight=vendor kernel command line option, there is only an intel_backlight directory in /sys/class/backlight. Brightness does work using "brightness up and down" function keys, with 'udevadm monitor' I can see it uses the intel_backlight: bertrik@netbook:~$ udevadm monitor monitor will print the received events for: UDEV - the event which udev sends out after rule processing KERNEL - the kernel uevent KERNEL[40.375921] change /devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight (backlight) UDEV [40.503704] change /devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight (backlight) With kind regards, Bertrik Sikken