[Lenovo ThinkPad T430s] Brightness bug in kernel 3.13 when using Docking station

[Matthias Baur]

When undocking my Thinkpad T30s from my dockingstation, the brightness is set to the lowest level and can't be changed.

Workaround:
- Dock/Undock again. After the second undocking the brightness level can be changed. Rule of thumb: Every uneven undocking won't work.
- Reboot

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-36-generic 3.13.0-36.63
ProcVersionSignature: Ubuntu 3.13.0-36.63-generic 3.13.11.6
Uname: Linux 3.13.0-36-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: s0me0ne 3001 F.... pulseaudio
Date: Tue Oct 7 17:35:56 2014
HibernationDevice: RESUME=UUID=af9ba4ae-e55a-4140-ada0-b0fe89caa5ff
InstallationDate: Installed on 2014-09-21 (16 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
MachineType: LENOVO 2356LNG
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.13.0-36-generic.efi.signed root=/dev/mapper/ubuntu--vg-root ro quiet splash vt.handoff=7
PulseList:
 Error: command ['pacmd', 'list'] failed with exit code 1: Home directory not accessible: Permission denied
 No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-36-generic N/A
 linux-backports-modules-3.13.0-36-generic N/A
 linux-firmware 1.127.7
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/14/2014
dmi.bios.vendor: LENOVO
dmi.bios.version: G7ETA0WW (2.60 )
dmi.board.asset.tag: Not Available
dmi.board.name: 2356LNG
dmi.board.vendor: LENOVO
dmi.board.version: Win8 Pro MBR TPG
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvrG7ETA0WW(2.60):bd05/14/2014:svnLENOVO:pn2356LNG:pvrThinkPadT430s:rvnLENOVO:rn2356LNG:rvrWin8ProMBRTPG:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 2356LNG
dmi.product.version: ThinkPad T430s
dmi.sys.vendor: LENOVO

[Joseph Salisbury (jsalisbury)]

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v3.17 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

If you are unable to test the mainline kernel, for example it will not boot, please add the tag: 'kernel-unable-to-test-upstream'.
Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.17-utopic/

[Brad Figg (brad-figg)]

This change was made by a bot.

[Matthias Baur (matthiasbaur)]

Awesome, it works perfectly with 3.17. Since 14.10 will have 3.16 as kernel, when will it be available for Ubuntu?

[penalvch (penalvch)]

Matthias Baur, the next step is to fully reverse commit bisect the kernel in order to identify the fix commit. Could you please do this following https://wiki.ubuntu.com/Kernel/KernelBisection#How_do_I_reverse_bisect_the_upstream_kernel.3F ?

[Matthias Baur (matthiasbaur)]

Will do, but i guess not before the weekend. Tonight i've did some easy debugging by just installing some old version (3.14-3.16) of the mainline kernel. It showed, that the actual bug (not being able to adjust the brightness level after undocking) is fixed in those versions as well, but there is some other strange stuff going on. After every undocking the screen is just black. I first thought the OS/windows manger/... crashed, but after some testing it showed, that the brightness level was just set to the lowest possible value which just meant that the display is black/dark. So with 3.14-3.16 the actual bug is fixed but there is some really non-user-friendly behavior with just a black/dark screen.
So i guess i should first bisect 3.13 against 3.14 to find the actual bug(fix)? And after that bisect 3.14 against 3.17 to find the bugfix for the black/dark screen behavior. Right?

[Matthias Baur (matthiasbaur)]

I'm so sorry, i didn't get to it and now traveling the world for a year without my docking station. Hope someone else finds the time to bisect this problem.

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]