Ubuntu
linux package

  1. Bug #1208257
  2. Comment #53

Comment 53 for bug 1208257

Revision history for this message
Mantas Kriaučiūnas (mantas) wrote :

I can confirm this bug on several HP Probooks, including HP ProBook 4740s with Ubuntu 12.04.3 LTS (Precise) daily-live 2013-08-18 (from http://cdimage.ubuntu.com/precise/), which has Linux kernel 3.8 (tested with several linux-image-generic-lts-raring versions, including the latest - 3.8.0-29-generic)

Changing screen brighness works fine if I add boot parameter acpi_backlight=vendor in Ubuntu 12.04.3 LiveCD or installed system.

Another workaround is to install older Linux kernel 3.5 from Ubuntu 12.04.2:
sudo apt-get install linux-image-generic-lts-quantal

So, problem is

Btw, this HP Probook has 2 video chipsets:

ubuntu@ubuntu:~$ lspci |grep -i VGA
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Thames [Radeon HD 7550M/7570M/7650M]

I'm attachink /var/log/Xorg.0.log file when using 3.8.0-29-generic kernel (Ubuntu 12.04.3 LiveCD)