Public bug reported: The Pixel Slate/nocturne backlight does not work due to DPCD logic not identifying the DPCD backlight connection since there is no PWM on the nocturne or eve devices.
ChromeOS documentation of disconnected PWM: https://chromium- review.googlesource.com/c/chromiumos/overlays/board-overlays/+/1171922 Discussion of issue & solution: https://github.com/EmbeddedAndroid /linux-eve/issues/2#issuecomment-561382927 This can be fixed with a simple patch which I have applied successfully to mainline 5.9-rc5: https://gist.github.com/satmandu/d6c2192f66cd14525049fd34d356d71d Luckily the Ubuntu kernel patches set i915.enable_psr=0 which keeps Panel Self Refresh from dimming the backlight at boot, but that isn't even needed for this device once the backlight is hooked up correctly. (As a bonus the keyboard backlight also starts working properly at boot.) ProblemType: Bug DistroRelease: Ubuntu 20.10 Package: linux-image-lowlatency 5.8.0.18.22 ProcVersionSignature: Ubuntu 5.8.0-18.19-lowlatency 5.8.4 Uname: Linux 5.8.0-18-lowlatency x86_64 ApportVersion: 2.20.11-0ubuntu45 Architecture: amd64 AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: CasperMD5CheckResult: skip Date: Mon Sep 14 23:52:45 2020 InstallationDate: Installed on 2020-08-24 (21 days ago) InstallationMedia: Ubuntu 20.10 "Groovy Gorilla" - Alpha amd64 (20200728) Lsusb: Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 003: ID 18d1:5030 Google Inc. Hammer Bus 001 Device 002: ID 8087:0a2a Intel Corp. Bluetooth wireless interface Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub MachineType: Google Nocturne ProcEnviron: TERM=xterm-256color PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.8.0-18-lowlatency root=UUID=90e26b2a-aaad-4576-8e90-1962b97d4e96 ro fsck.repair=yes fsck.mode=force 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-5.8.0-18-lowlatency N/A linux-backports-modules-5.8.0-18-lowlatency N/A linux-firmware 1.190 SourcePackage: linux StagingDrivers: ipu3_imgu UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 06/04/2019 dmi.bios.release: 4.0 dmi.bios.vendor: coreboot dmi.bios.version: Google_Nocturne.10984.90.0 dmi.board.name: Nocturne dmi.board.vendor: Google dmi.board.version: 1.0 dmi.chassis.type: 3 dmi.chassis.vendor: Google dmi.ec.firmware.release: 0.0 dmi.modalias: dmi:bvncoreboot:bvrGoogle_Nocturne.10984.90.0:bd06/04/2019:br4.0:efr0.0:svnGoogle:pnNocturne:pvr1.0:rvnGoogle:rnNocturne:rvr1.0:cvnGoogle:ct3:cvr: dmi.product.family: Google_Nocturne dmi.product.name: Nocturne dmi.product.version: 1.0 dmi.sys.vendor: Google ** Affects: linux (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug groovy staging ** Patch added: "DPCD Backlight enablement for Google nocturne (and possibly Google eve device as well.)" https://bugs.launchpad.net/bugs/1895615/+attachment/5410883/+files/dpcd59.patch -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1895615 Title: Backlight adjustment doesn't work on Google Pixel Slate To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1895615/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
