Public bug reported: Hi,
Problem: With current kernels (both Ubuntu kernels and mainline kernels) the display backlight in one of our tablet variants does not work because i915 GFX driver lacks support for I2C transfers from display initialization VBT sequences and the backlight driver is left uninitialized. Ubuntu version: Ubuntu 20.04 daily build (downloaded on 2020-01-20) Device: Aava Mobile Inari10B tablet (Intel Apollolake platform) Existing fixes: Intel has implement a kernel fix for this problem and it is currently on its way to 5.6 kernel (https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/gpu/drm/i915/display/intel_dsi_vbt.c?h=next-20200129&id=8cbf89db294166cc13d90a89422605e0c9f8bbc2). Unfortunately that change is not working correctly as-is, further fix is currently in drm-intel-next-queued (https://cgit.freedesktop.org/drm/drm-intel/commit/?id=de409661c4c90d63cfc64579edbad0a6b10bd50d), which should also end up in 5.6 kernel because it has a fixes tag referring to the initial fix commit. Background information: Our company produces Intel Apollolake based tablets and some of our customers would like to use Ubuntu as the OS. Optimal situation would be that we could recommend Ubuntu 20.04 LTS release to our customers. Since I was unable to find conclusive information regarding which kernel version is going to end up in Ubuntu 20.04 LTS release, I decided to open this bug to resolve if and how the fix for backlight problem could get included in Ubuntu 20.04 LTS release in it's first version. BR, Mikko Kovanen ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.4.0-9-generic 5.4.0-9.12 ProcVersionSignature: Ubuntu 5.4.0-9.12-generic 5.4.3 Uname: Linux 5.4.0-9-generic x86_64 NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair ApportVersion: 2.20.11-0ubuntu15 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: ubuntu 1708 F.... pulseaudio CasperVersion: 1.438 CurrentDesktop: ubuntu:GNOME Date: Thu Jan 30 07:30:24 2020 LiveMediaBuild: Ubuntu 20.04 LTS "Focal Fossa" - Alpha amd64 (20200124) MachineType: OEM ApolloLake ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=C.UTF-8 SHELL=/bin/bash ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/username.seed quiet splash --- RelatedPackageVersions: linux-restricted-modules-5.4.0-9-generic N/A linux-backports-modules-5.4.0-9-generic N/A linux-firmware 1.184 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/11/2019 dmi.bios.vendor: INSYDE Corp. dmi.bios.version: W-02.52 dmi.board.asset.tag: NA dmi.board.name: NA dmi.board.vendor: OEM dmi.board.version: NA dmi.chassis.asset.tag: NA dmi.chassis.type: 10 dmi.chassis.vendor: OEM dmi.chassis.version: NA dmi.modalias: dmi:bvnINSYDECorp.:bvrW-02.52:bd12/11/2019:svnOEM:pnApolloLake:pvrNA:rvnOEM:rnNA:rvrNA:cvnOEM:ct10:cvrNA: dmi.product.family: Apollolake dmi.product.name: ApolloLake dmi.product.sku: 0 dmi.product.version: NA dmi.sys.vendor: OEM ** Affects: linux (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug focal -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1861380 Title: Internal display backlight not working on a Intel Apollolake based tablet To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1861380/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
