** Description changed: + [Impact] + After Ubuntu-5.4.0-9.12 which introduce DPCD backlight patches, the + backlight control on some platforms fail to work. + It seems using OUI string to map the panels which support DPCD + backlight doesn't work well, it mis-mapped those panel that doesn't + support DPCD backlight, and breaks the backlight control. + + [Fix] + The author of the origin DPCD backlight patches recently provides a + DP quirks based on EDID identification. + + [Fix] + Verified on the machine with DPCD backlight and also on the machine + which has regression with the OUI quirks, both of them work now. + + [Regression Potential] + Low, it introduce a new quirks to list the panels which support DPCD + backlight. + + =============================== + After upgrading from Eoan (5.3.0-29.31) to Focal (5.4.0-12.15), I no longer have the ability to control the backlight brightness on my HP EliteBook 840 G5. When pressing the brightness hotkeys, the on-screen indicator pops up and shows that the brightness setting is being changed but the actual screen brightness is stuck on the lowest setting. This laptop has a built-in privacy screen. If I activate the privacy screen (fn-f2), then the actual screen brightness goes to the maximum setting and then I am able to dim and brighten the backlight as long as the privacy screen functionality is turned on. This is a regression from Eoan's 5.3.0-29.31 kernel where I was able to control the brightness with and without the privacy screen functionality being turned on. ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.4.0-12-generic 5.4.0-12.15 ProcVersionSignature: Ubuntu 5.4.0-12.15-generic 5.4.8 Uname: Linux 5.4.0-12-generic x86_64 NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair ApportVersion: 2.20.11-0ubuntu16 Architecture: amd64 CurrentDesktop: ubuntu:GNOME Date: Fri Jan 31 11:42:16 2020 InstallationDate: Installed on 2019-06-24 (221 days ago) InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Release amd64 (20190416) ProcEnviron: - TERM=xterm-256color - PATH=(custom, no user) - XDG_RUNTIME_DIR=<set> - LANG=en_US.UTF-8 - SHELL=/bin/bash + TERM=xterm-256color + PATH=(custom, no user) + XDG_RUNTIME_DIR=<set> + LANG=en_US.UTF-8 + SHELL=/bin/bash SourcePackage: linux-signed-5.4 UpgradeStatus: Upgraded to focal on 2020-01-28 (3 days ago)
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-5.4 in Ubuntu. https://bugs.launchpad.net/bugs/1861521 Title: [FOCAL][REGRESSION] Intel Gen 9 brightness cannot be controlled Status in linux-5.4 package in Ubuntu: In Progress Status in linux-5.4 source package in Focal: In Progress Bug description: [Impact] After Ubuntu-5.4.0-9.12 which introduce DPCD backlight patches, the backlight control on some platforms fail to work. It seems using OUI string to map the panels which support DPCD backlight doesn't work well, it mis-mapped those panel that doesn't support DPCD backlight, and breaks the backlight control. [Fix] The author of the origin DPCD backlight patches recently provides a DP quirks based on EDID identification. [Fix] Verified on the machine with DPCD backlight and also on the machine which has regression with the OUI quirks, both of them work now. [Regression Potential] Low, it introduce a new quirks to list the panels which support DPCD backlight. =============================== After upgrading from Eoan (5.3.0-29.31) to Focal (5.4.0-12.15), I no longer have the ability to control the backlight brightness on my HP EliteBook 840 G5. When pressing the brightness hotkeys, the on-screen indicator pops up and shows that the brightness setting is being changed but the actual screen brightness is stuck on the lowest setting. This laptop has a built-in privacy screen. If I activate the privacy screen (fn-f2), then the actual screen brightness goes to the maximum setting and then I am able to dim and brighten the backlight as long as the privacy screen functionality is turned on. This is a regression from Eoan's 5.3.0-29.31 kernel where I was able to control the brightness with and without the privacy screen functionality being turned on. ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.4.0-12-generic 5.4.0-12.15 ProcVersionSignature: Ubuntu 5.4.0-12.15-generic 5.4.8 Uname: Linux 5.4.0-12-generic x86_64 NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair ApportVersion: 2.20.11-0ubuntu16 Architecture: amd64 CurrentDesktop: ubuntu:GNOME Date: Fri Jan 31 11:42:16 2020 InstallationDate: Installed on 2019-06-24 (221 days ago) InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Release amd64 (20190416) ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: linux-signed-5.4 UpgradeStatus: Upgraded to focal on 2020-01-28 (3 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-5.4/+bug/1861521/+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
