For the record I haven't experienced this bug since upgrading to Ubuntu 14.10 (on release day, i.e. the 24th of October, 2014).
-- 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/1378863 Title: ThinkPad X220: unplugging DisplayPort breaks backlight (intel video) Status in “linux” package in Ubuntu: Triaged Bug description: Steps to reproduce: 1. Plug in an external monitor using a DisplayPort -> HDMI cable 2. Unplug the cable What happens about 30% of the time: - Brightness of laptop's internal LCD drops to lowest level - Brightness keys (Fn-Home/End on this Lenovo ThinkPad X220) produce the gnome-shell on-screen display of the changing brightness meter, but actual LCD brightness doesn't change. There are a couple of workarounds: 1. Ctrl+Alt+F1 and use Fn-Home/End to control brightness, then Ctrl+Alt+F7 back to X (where brightness keys continue to not work) or 2. Plug/unplug DisplayPort again, this usually fixes the brigthness (maybe 60% of the time) I've been having this problem on this laptop since January of 2014. I was running Ubuntu 13.10 then, I'm running 14.04 now. Sometimes the brightness-drop-and-you-can't-fix-it thing happens on DisplayPort hotplug rather than on unplug. ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.13.0-37-generic 3.13.0-37.64 ProcVersionSignature: Ubuntu 3.13.0-37.64-generic 3.13.11.7 Uname: Linux 3.13.0-37-generic x86_64 ApportVersion: 2.14.1-0ubuntu3.4 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: mg 3318 F.... pulseaudio CurrentDesktop: GNOME Date: Wed Oct 8 17:35:50 2014 EcryptfsInUse: Yes HibernationDevice: RESUME=UUID=bf592a79-5f4e-486d-b69d-7525d492dcc6 InstallationDate: Installed on 2012-07-25 (805 days ago) InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425) Lsusb: Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub MachineType: LENOVO 4291WJF ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-37-generic root=UUID=36079681-53fc-4ca2-80ac-98321c07e8d2 ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.13.0-37-generic N/A linux-backports-modules-3.13.0-37-generic N/A linux-firmware 1.127.7 RfKill: 0: phy0: Wireless LAN Soft blocked: no Hard blocked: no SourcePackage: linux UpgradeStatus: Upgraded to trusty on 2014-04-18 (173 days ago) dmi.bios.date: 07/18/2013 dmi.bios.vendor: LENOVO dmi.bios.version: 8DET69WW (1.39 ) dmi.board.asset.tag: Not Available dmi.board.name: 4291WJF 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:bvr8DET69WW(1.39):bd07/18/2013:svnLENOVO:pn4291WJF:pvrThinkPadX220:rvnLENOVO:rn4291WJF:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable: dmi.product.name: 4291WJF 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/1378863/+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
