Here is a new test kernel which not only revert the quirk, but introduce a new way to quirk the panels which support DPCD backlight https://people.canonical.com/~acelan/bugs/lp1861521/
-- 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/1858844 Title: [Dell XPS 15 9575] Screen brightness stopped working with linux- image-5.4.0-9-generic Status in linux package in Ubuntu: Confirmed Bug description: I upgraded to Focal Fossa 3 days ago and nothing broke. At the time, it was still using linux 5.3 (linux-image-5.3.0-24-generic). Today, it updated to linux 5.4 (linux-image-5.4.0-9-generic) and after rebooting, the screen brightness does not work anymore - neither from keyboard keys nor from the slider in the gnome-shell panel. It works again when rebooting into the previous linux- image-5.3.0-24-generic kernel. 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 ApportVersion: 2.20.11-0ubuntu15 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: mario 1892 F.... pulseaudio CurrentDesktop: ubuntu:GNOME Date: Wed Jan 8 20:23:31 2020 InstallationDate: Installed on 2018-09-13 (481 days ago) InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Alpha amd64 (20180912) MachineType: Dell Inc. XPS 15 9575 ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-9-generic root=UUID=26ff4c95-5f68-4121-b7d0-989fa705fcc8 ro 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: Upgraded to focal on 2020-01-04 (3 days ago) dmi.bios.date: 07/07/2019 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.7.1 dmi.board.name: 0C32VW dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 31 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvr1.7.1:bd07/07/2019:svnDellInc.:pnXPS159575:pvr:rvnDellInc.:rn0C32VW:rvrA00:cvnDellInc.:ct31:cvr: dmi.product.family: XPS dmi.product.name: XPS 15 9575 dmi.product.sku: 080D dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1858844/+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
