Bug 43741

Summary: /sys/class/backlight/ is empty with AMD (ATI) Radeon HD 4350
Product: Drivers Reporter: rpr.nospam
Component: Video(DRI - non Intel)Assignee: drivers_video-dri
Status: RESOLVED CODE_FIX    
Severity: normal CC: alan, alexdeucher, rpr.nospam, rui.zhang
Priority: P1    
Hardware: x86-64   
OS: Linux   
Kernel Version: 3.2.0-26-generic Tree: Mainline
Regression: No
Bug Depends on:    
Bug Blocks: 56331    
Attachments: /var/log/dmesg
output of lsmod
output of 'sudo lspci -vvnn'
output of 'sudo acpidump'

Description rpr.nospam 2012-06-25 10:53:31 UTC
Created attachment 74171 [details]
/var/log/dmesg

Hi!

On an Ubuntu 12.04 PC with Linux 3.2.0-26-generic x86_64 and
AMD (ATI) Radeon HD 4350 VGA controller the kernel does not recognize
the ability of the VGA to change brightness of the connected monitor
(HP LA2405wg).

/sys/class/backlight/ is empty and tools for brightness control report
errors. I tried the following options in /etc/default/grub (and
updated grub configuration after the change):

GRUB_CMDLINE_LINUX="pcie_aspm=force acpi_osi=Linux acpi_backlight=vendor"

but to no avail.

-- rpr.
Comment 1 rpr.nospam 2012-06-25 10:54:30 UTC
Created attachment 74181 [details]
output of lsmod
Comment 2 rpr.nospam 2012-06-25 10:55:51 UTC
Created attachment 74191 [details]
output of 'sudo lspci -vvnn'
Comment 3 rpr.nospam 2012-06-25 10:56:44 UTC
Created attachment 74201 [details]
output of 'sudo acpidump'
Comment 4 Zhang Rui 2012-11-13 07:36:26 UTC
there is no ACPI Backlight control on your laptop.
so sorry I can not help you on this.

re-assign to the graphics expert.
Comment 5 Alex Deucher 2012-11-13 13:27:11 UTC
If your laptop uses the backlight controller on the GPU, there is support for it in kernel 3.7.