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brodo 07-28-2012 10:54 AM

Less backlight steps after current upgrades
 
Hi,

After upgrading to all the latest stuff, there are only 4 backlight steps using Fn-Home and Fn-End keys in my X60s Lenovo baby.

Normally, there should be 8 of them.
I have 8 while booting my machine, but after running XFCE, only 4 are left.... :-(

Any ideas folks ?

Didier Spaier 07-28-2012 01:18 PM

On a T61 I have 16 steps (0 to 15) all accessible under Fluxbox, and less (but bigger) under KDE or XFCE.

It seems that both KDE and XFCE make "big steps" in grouping it somehow.

But you can set it yourself in a terminal or xterm, e.g.

Code:

bash-4.2# pwd
/sys/class/backlight/acpi_video0
bash-4.2# ls
actual_brightness  bl_power  brightness  device  max_brightness  power  subsystem  type  uevent
bash-4.2# cat max_brightness
15
bash-4.2# cat brightness
3
bash-4.2# echo 10 > brightness
bash-4.2# cat brightness
10
bash-4.2#

The exact directory differ upon models, there is a /proc interface also but which could be deprecated.

To know more, read /usr/src/linux-3.2.23/Documentation/laptops/thinkpad-acpi.txt

PS You can set some parameters when loading the driver, see the documentation and (as root) "modinfo thinkad-acpi" for a summary.

brodo 07-29-2012 08:47 AM

Code:

bash-4.2# pwd
/sys/class/backlight/acpi_video0
bash-4.2# ls
actual_brightness  bl_power  brightness  device  max_brightness  power  subsystem  type  uevent
bash-4.2# cat max_brightness
15
bash-4.2# cat brightness
3
bash-4.2# echo 10 > brightness
bash-4.2# cat brightness
10
bash-4.2#

This works, thanks.

Is it possible to correct/patch the sources of "xfce4-power-manager-1.2.0" in order to
get those 8 steps back again ?
Seems that today's state (4 steps) is little abnormal - I never messed with acpi through the years of using Slack on my Thinkpads ...

Didier Spaier 07-29-2012 12:40 PM

Quote:

Originally Posted by brodo (Post 4740553)
[CODE]
Is it possible to correct/patch the sources of "xfce4-power-manager-1.2.0" in order to
get those 8 steps back again ?

I think that the suspect is src/xfpm-backlight-helper.c.

Unfortunately I am not able to find out why the level can't be incremented or decremented by value of one.

Maybe somebody here is better at reading C code than I am, or you could ask in a xfce mailing-list or forum...

I just noticed that, as the programmer has to cope with a lot of different models of laptops, he or she tries no less than 11 kernel interfaces, fortunately all located in /sys/class/backlight.


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