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:
USERPID 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=
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
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https://bugs.launchpad.net/bugs/1861380
Title:
Internal display backlight not working on a Intel Apollolake based
tablet
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