xorg, i810 and DPMS

[Marcelo Magno T. Sales]

People,

I have a Centrino notebook with Intel 915GM video chipset, which uses 
the i810 xorg driver.
However, DPMS is not working right. 
I configure KDE to turn off the display after 20 minutes of 
inactivity. The display turns itself off after this time, but then 
the backlight turns on again after 10 seconds or so and the screen 
remains blank.
If I command "xset dpms force off", the same thing happens: the 
display turns off and the backlight turns on again after 10 seconds. 
"vbetool dpms off", however, works as expected.
Option "dpms" is set to "on" in xorg.conf. Is this a bug or a 
misconfiguration?

Thanks,

Marcelo