** Package changed: linux-5.4 (Ubuntu Focal) => linux (Ubuntu Focal)

** Changed in: linux (Ubuntu Focal)
       Status: In Progress => Fix Released

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  [FOCAL][REGRESSION] Intel Gen 9 brightness cannot be controlled

Status in linux package in Ubuntu:
  Fix Released
Status in linux-oem-osp1 package in Ubuntu:
  Fix Released
Status in linux-oem-osp1 source package in Bionic:
  Fix Released
Status in linux source package in Focal:
  Fix Released

Bug description:
  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.
  The author of the origin DPCD backlight patches recently provides a
  DP quirks based on EDID identification.

  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


  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

  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)
   PATH=(custom, no user)
  SourcePackage: linux-signed-5.4
  UpgradeStatus: Upgraded to focal on 2020-01-28 (3 days ago)

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