Hi guys, I've fixed this situation with a workaround (please forgive my bad english) on fedora and for sure the same can be applied with ubuntu. in the specific:
i installed brightnessctl and discovered the max value for light, in my case 24242. after that, i create a shortcut on keyboard (used kdeplasma in my case) and applied the f6 button (my laptop is thinkpad t14 gen1) the command brightnessctl set 24242. now, finally, when i unplug the external dock station with only pressing f6 i will see the internal screen correctly. i hope that this will help someone -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1308674 Title: [Lenovo ThinkPad X220] kernel 3.13 i915 brightness settings broken when going from docked -> undocked Status in linux package in Ubuntu: Invalid Bug description: This happens on my X220, running trusty, linux 3.13.0-24-generic. It's the exact same problem discussed on https://bugzilla.redhat.com/show_bug.cgi?id=1067071. Discussed also on kernel mailing list: https://lkml.org/lkml/2014/2/19/720. It worked on 3.12, and upstream acknowledges the regression. To reproduce, remove the X220 from the dock. The brightness is set to minimum (the screen is nearly unreadable) and the brightness control is broken, you can't adjust it by hardware keys. My hardware: 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller]) Subsystem: Lenovo Device 21da Kernel driver in use: i915 Docked on a ThinkPad mini dock series 3. I have nothing much relevant in /var/log/syslog. Below there are excerpts of it when brightness is working: Apr 16 14:55:37 galactica kernel: [79261.217384] [drm:asle_set_backlight], bclp = 0x800000ff Apr 16 14:55:37 galactica kernel: [79261.217390] [drm:asle_set_backlight], updating opregion backlight 255/255 Apr 16 14:55:37 galactica kernel: [79261.217394] [drm:intel_panel_get_max_backlight], max backlight PWM = 4648 Apr 16 14:55:37 galactica kernel: [79261.217396] [drm:intel_panel_actually_set_backlight], set backlight PWM = 4590 Apr 16 14:55:37 galactica kernel: [79261.217537] [drm:asle_set_pwm_freq], PWM freq is not supported And brightness not working: Apr 16 15:23:46 galactica kernel: [80948.263160] [drm:asle_set_backlight], bclp = 0x80000058 Apr 16 15:23:46 galactica kernel: [80948.263168] [drm:asle_set_pwm_freq], PWM freq is not supported Apr 16 15:23:46 galactica kernel: [80948.280637] [drm:asle_set_backlight], bclp = 0x80000041 Apr 16 15:23:46 galactica kernel: [80948.280642] [drm:asle_set_pwm_freq], PWM freq is not supported A workaround is to echo values directly to /sys/class/backlight/intel_backlight/brightness. Maximum brightness is 4648 (/sys/class/backlight/intel_backlight/max_brightness). e.g.: # echo 500 > /sys/class/backlight/intel_backlight/brightness ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.13.0-24-generic 3.13.0-24.46 ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9 Uname: Linux 3.13.0-24-generic i686 ApportVersion: 2.14.1-0ubuntu2 Architecture: i386 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: ursula 3881 F.... pulseaudio /dev/snd/controlC0: ursula 3881 F.... pulseaudio CurrentDesktop: Unity Date: Wed Apr 16 15:09:23 2014 HibernationDevice: RESUME=UUID=68890e28-0eee-4184-9456-cc267c4a5f31 InstallationDate: Installed on 2013-05-27 (323 days ago) InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release i386 (20130213) MachineType: LENOVO 4286CTO ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-24-generic root=UUID=4db5451d-c250-47bc-9c4e-235fb1967ee5 ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.13.0-24-generic N/A linux-backports-modules-3.13.0-24-generic N/A linux-firmware 1.127 SourcePackage: linux UpgradeStatus: Upgraded to trusty on 2013-11-04 (162 days ago) dmi.bios.date: 12/01/2011 dmi.bios.vendor: LENOVO dmi.bios.version: 8DET56WW (1.26 ) dmi.board.asset.tag: Not Available dmi.board.name: 4286CTO dmi.board.vendor: LENOVO dmi.board.version: Not Available dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: Not Available dmi.modalias: dmi:bvnLENOVO:bvr8DET56WW(1.26):bd12/01/2011:svnLENOVO:pn4286CTO:pvrThinkPadX220:rvnLENOVO:rn4286CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable: dmi.product.name: 4286CTO dmi.product.version: ThinkPad X220 dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1308674/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
