[FOCAL][REGRESSION] Intel Gen 9 brightness cannot be controlled
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Fix Released
|
Medium
|
AceLan Kao | ||
Focal |
Fix Released
|
Medium
|
AceLan Kao | ||
linux-oem-osp1 (Ubuntu) |
Fix Released
|
Undecided
|
Unassigned | ||
Bionic |
Fix Released
|
Undecided
|
Unassigned |
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-
ProcVersionSign
Uname: Linux 5.4.0-12-generic x86_64
NonfreeKernelMo
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-
PATH=(custom, no user)
XDG_RUNTIME_
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: linux-signed-5.4
UpgradeStatus: Upgraded to focal on 2020-01-28 (3 days ago)
summary: |
- [FOCAL][REGRESSION] HP EliteBook 840 G5 screen brightness cannot be - controlled + [FOCAL][REGRESSION] Intel Gen 9 brightness cannot be controlled |
affects: | linux-signed-5.4 (Ubuntu) → linux-5.4 (Ubuntu) |
tags: | added: champagne |
description: | updated |
no longer affects: | linux-5.4 (Ubuntu Bionic) |
no longer affects: | linux-oem-osp1 (Ubuntu Focal) |
Changed in linux-oem-osp1 (Ubuntu Bionic): | |
status: | New → Fix Committed |
Changed in linux-oem-osp1 (Ubuntu): | |
status: | New → Invalid |
Changed in linux-oem-osp1 (Ubuntu): | |
status: | Invalid → Fix Released |
affects: | linux-5.4 (Ubuntu Focal) → linux (Ubuntu Focal) |
Changed in linux (Ubuntu Focal): | |
status: | In Progress → Fix Released |
When the privacy screen functionality is enabled, I see the following warnings in the logs:
[188829.782403] hp_wmi: Unknown event_id - 20 - 0x46fe
[188834.848948] hp_wmi: Unknown event_id - 20 - 0x3c00
[188835.624987] hp_wmi: Unknown event_id - 20 - 0x4600
The first warning is when I press the privacy screen button (fn-f2). The second is when I press the brightness down button (fn-f3). The third is when I press the brightness up button (fn-f4).
I do not see similar warnings after the privacy screen functionality is turned off and I press the brightness up or down hotkeys.