Neale Upstone: >" This bug is with Lenovo vendor backlight" The bug is not with the Lenovo vendor backlight. It's either a bug in the linux kernel (likely), or a bug in the BIOS.
>"The guidance on investigating backlight issues..." As is noticed in the guidance, it doesn't tell you to use it forever, but as a debugging step to see if that allows one to change the backlight if one is having an issue with it. This information tells developers where to look within the code to search for a bug depending on the outcome. Also, you don't need to advise on the contents of the article, given I've contributed towards it as per https://wiki.ubuntu.com/Kernel/Debugging/Backlight?action=info . Hence, could you please answer the question asked in https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1516370/comments/9 ? ** Tags added: needs-bisect regression-update -- 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/1516370 Title: Vendor backlight on Lenovo Z580 having random hotkeys issues Status in linux package in Ubuntu: Incomplete Bug description: I've taken a bold guess in the title of this bug. While investigating why on 14.04 LTS, I have working backlight on the latest 3.13 kernel, but not on the 3.16, I tried acpi_backlight=vendor. With default boot parameters, I just get /sys/class/backlight/intel_backlight/, and the backlight works correctly on 3.13, but does not change the brightness on 3.16 (the OSD does show that the hotkeys are trying to change the brightness). With acpi_backlight=vendor, I get both intel and /lenovo/. The key point for this bug report is what happens with the lenovo one: The hotkeys work and make the backlight change, but not consistently. Repeatedly using the hotkey to increase the brightness causes the level to increase, but then occasionally reset to zero (including resetting as shown in the OSD - i.e. the OSD is always showing the level that the backlight actually is). Occasionally the OSD shows the "enable touchpad" icon when pressing the increase brightness hotkey repeatedly. The same action also causes the wifi to enable/disable randomly. If I press the hotkey with pauses in between, things behave normally. ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.13.0-67-generic 3.13.0-67.110 ProcVersionSignature: Ubuntu 3.13.0-67.110-generic 3.13.11-ckt27 Uname: Linux 3.13.0-67-generic x86_64 NonfreeKernelModules: nvidia ApportVersion: 2.14.1-0ubuntu3.18 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: neale 3106 F.... pulseaudio CurrentDesktop: Unity Date: Sun Nov 15 11:16:55 2015 HibernationDevice: RESUME=UUID=1fd50851-1727-4432-a99c-d0be8aafc983 InstallationDate: Installed on 2013-10-23 (752 days ago) InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1) MachineType: LENOVO IdeaPad Z580 ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-67-generic root=UUID=d66417de-a540-485b-b469-aabd51a8844b ro quiet splash acpi_backlight=vendor RelatedPackageVersions: linux-restricted-modules-3.13.0-67-generic N/A linux-backports-modules-3.13.0-67-generic N/A linux-firmware 1.127.18 SourcePackage: linux StagingDrivers: rts5139 UpgradeStatus: Upgraded to trusty on 2014-03-17 (607 days ago) dmi.bios.date: 12/25/2012 dmi.bios.vendor: Phoenix Technologies Ltd. dmi.bios.version: 5FCN95WW dmi.board.asset.tag: No Asset Tag dmi.board.name: Lenovo dmi.board.vendor: LENOVO dmi.board.version: 31900003WIN8 STD MLT dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: Lenovo Z580 dmi.modalias: dmi:bvnPhoenixTechnologiesLtd.:bvr5FCN95WW:bd12/25/2012:svnLENOVO:pnIdeaPadZ580:pvrLenovoZ580:rvnLENOVO:rnLenovo:rvr31900003WIN8STDMLT:cvnLENOVO:ct10:cvrLenovoZ580: dmi.product.name: IdeaPad Z580 dmi.product.version: Lenovo Z580 dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1516370/+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
