[ltp] How to turn off LCD backlight by software?

[Georg Sauthoff]

Hi,

after I disabled APIC in the kernel, suspend and resume works well with the 
Thinkpad R40.

Manually I can turn off the LCD backlight with Fn+F3.

But the DPMS settings have no effect at the backlight.

Is there any possibility to turn the backlight off by software?

Regards
Georg Sauthoff