Bug 61979 - backlight adjustment doesn't work on HP Pavilion m6-1035dx
Summary: backlight adjustment doesn't work on HP Pavilion m6-1035dx
Status: RESOLVED FIXED
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Radeon (show other bugs)
Version: unspecified
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Default DRI bug account
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Reported: 2013-03-07 18:03 UTC by S. Christian Collins
Modified: 2013-03-08 18:16 UTC (History)
0 users

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Description S. Christian Collins 2013-03-07 18:03:12 UTC 
I am unable to adjust the backlight on my laptop when using the open-source radeon driver, but backlight adjustments to work correctly when using fglrx. xbacklight reports that "No outputs have backlight property".

Now, if I recall correctly, the backlight used to work before I updated the BIOS on this laptop. Prior to the BIOS update, the backlight setting worked in the radeon driver, but was flaky in fglrx. After the update, the backlight setting works correctly in fglrx but not radeon.

Please let me know what information I can provide to help resolve this issue.

Here is my system info:

OS: Kubuntu 12.04 amd64 w/ KDE SC 4.10.1
PC: HP Pavilion m6-1035dx
CPU/GPU: AMD A10-4600M APU with Radeon(tm) HD Graphics
RAM: 6GB DDR3 800 MHz
Linux Kernel: 3.5.0-25-generic
Screen Resolution: 1366 x 768
Xserver: 1.12.3+git20120709+server-1.12-branch.60e0d205
Comment 1 Alex Deucher 2013-03-07 18:13:31 UTC 
You are probably using the apci backlight interface which it seems to have been broken by the bios update.  Assuming your laptop uses the on-GPU backlight controller, you should be able to use the standard kernel backlight interface (/sys/class/backlight/) to control it if you have kernel 3.7 or newer.
Comment 2 S. Christian Collins 2013-03-08 18:16:47 UTC 
I tested the newer kernel by using a Kubuntu Raring CD, and the backlight adjustments work fine with the Radeon driver. So, I am marking this bug as fixed.

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