[HP EliteBook 725 G2 Notebook PC] brightness could not be controlled by the function key and the slider of "System settings -> Brightness and Lock" but sysfs works

[Taihsiang Ho]

HP EliteBook 725 G2 Notebook PC
(CID 201405-15214)
updated Ubuntu 14.04.1
3.13.0-43-generic #72

Steps to reproduce the bug:
1. install 12.04.3 on this machine
2. update the system via update manager to make the system up-to-date
3. click the upper-right indicator to launch the "System settings -> Brightness and Lock" applet
4. try to adjust the brightness slider to control the brightness
5. try to adjust the brightness by the function key fn+F8 or fn+F9

Expected result:
The brightness could be adjusted

Actual result:
screen brightness has no response

More information:
brightness has no response by using this command:
echo 4 | sudo tee -a /sys/class/backlight/acpi_video0/brightness

brightness HAS response by using this command:
echo 4 | sudo tee -a /sys/class/backlight/radeon_bl0/brightness

------------------------

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-43-generic 3.13.0-43.72
ProcVersionSignature: Ubuntu 3.13.0-43.72-generic 3.13.11.11
Uname: Linux 3.13.0-43-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.6
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: ubuntu 1417 F.... pulseaudio
 /dev/snd/controlC0: ubuntu 1417 F.... pulseaudio
CurrentDesktop: Unity
Date: Mon Jan 12 02:50:55 2015
HibernationDevice: RESUME=UUID=e24b803a-e217-4d6d-a35c-dbe0c033966a
InstallationDate: Installed on 2015-01-08 (3 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
IwConfig:
 eth0 no wireless extensions.

 lo no wireless extensions.
MachineType: Hewlett-Packard HP Licrice
ProcFB: 0 radeondrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-43-generic root=UUID=c1e0a265-8c75-4427-ad25-f0c76f003ce7 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-43-generic N/A
 linux-backports-modules-3.13.0-43-generic N/A
 linux-firmware 1.127.11
RfKill:
 0: hci0: Bluetooth
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/03/2014
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: M84 Ver. 97.35
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 221D
dmi.board.vendor: Hewlett-Packard
dmi.board.version: KBC Version 63.14
dmi.chassis.asset.tag: 73612P10CU
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvrM84Ver.97.35:bd09/03/2014:svnHewlett-Packard:pnHPLicrice:pvrA3009CD10002:rvnHewlett-Packard:rn221D:rvrKBCVersion63.14:cvnHewlett-Packard:ct10:cvr:
dmi.product.name: HP Licrice
dmi.product.version: A3009CD10002
dmi.sys.vendor: Hewlett-Packard

[Brad Figg (brad-figg)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v3.19 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

If you are unable to test the mainline kernel, for example it will not boot, please add the tag: 'kernel-unable-to-test-upstream'.
Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.19-rc4-vivid/

[Taihsiang Ho (tai271828)]

3.19.0-031900rc4-generic #201501112135
was tested, and this bug could be reproduced.

[Anthony Wong (anthonywong)]

I think this is the same BIOS bug we met in bug 1315972. It's reported that it's fixed with BIOS 92.12 and it's also the BIOS we used for pre-installed certification. Have you updated the BIOS to a new version?

[Launchpad Janitor (janitor)]

[Expired for HWE Next because there has been no activity for 60 days.]

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]