For my Thinkpad T430s, I can confirm that adding acpi_backlight=vendor as a grub boot option fixes the problem. I only have the Intel GPU enabled.
However, applying this boot options result in the OSD not correctly showing the current brightness state (s. attachment); it has always the same state. ** Attachment added: "Screenshot from 2013-09-27 01:44:43.png" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1221795/+attachment/3843507/+files/Screenshot%20from%202013-09-27%2001%3A44%3A43.png -- 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/1221795 Title: brightness stepping is incorrect (double what it should be) Status in “linux” package in Ubuntu: Incomplete Bug description: Problem: When I press the laptop screen brighteness, each step yield an event that is displayed on the OSD but the screen brightness doesn't change until the third press. Same happens for decreasing or increasing the brightness. Exepcted behaviour: Each press of the brightness button on the laptop, yield a visible change in the brightness of the LCD scree. Workaround: This seems documented and works perfectly. The work around is to type this in terminal: sudo sh -c 'echo -n 0 > /sys/module/video/parameters/brightness_switch_enabled' More details are here: http://askubuntu.com/questions/173921/why-does- my-thinkpad-brightness-control-skip-steps I think this should be fixed in 13.10. ProblemType: Bug DistroRelease: Ubuntu 13.10 Package: linux-image-3.11.0-4-generic 3.11.0-4.9 ProcVersionSignature: Ubuntu 3.11.0-4.9-generic 3.11.0-rc7 Uname: Linux 3.11.0-4-generic x86_64 ApportVersion: 2.12.1-0ubuntu3 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: anmar 1798 F.... pulseaudio Date: Fri Sep 6 11:23:20 2013 HibernationDevice: RESUME=UUID=2e39ee55-2a87-4298-a2d0-1c8ef5de5a96 InstallationDate: Installed on 2013-08-09 (27 days ago) InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Alpha amd64 (20130809) MachineType: LENOVO 3443CTO MarkForUpload: True ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-4-generic.efi.signed root=UUID=1784df7c-8b5f-4550-84f2-13e73c2915fe ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.11.0-4-generic N/A linux-backports-modules-3.11.0-4-generic N/A linux-firmware 1.113 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 04/29/2013 dmi.bios.vendor: LENOVO dmi.bios.version: G6ET96WW (2.56 ) dmi.board.asset.tag: Not Available dmi.board.name: 3443CTO dmi.board.vendor: LENOVO dmi.board.version: Win8 STD DPK 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:bvrG6ET96WW(2.56):bd04/29/2013:svnLENOVO:pn3443CTO:pvrThinkPadX1Carbon:rvnLENOVO:rn3443CTO:rvrWin8STDDPKTPG:cvnLENOVO:ct10:cvrNotAvailable: dmi.product.name: 3443CTO dmi.product.version: ThinkPad X1 Carbon dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1221795/+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
