Turn off LCD back light.

Hopefully, this is the correct place to ask such questions - I tried the
fbdev-users mailing list a couple of days ago, but is looks like it's
not currently very active.

I would like my laptop's  LCD panel to switch itself off automatically
after a few minutes of inactivity.

The /etc/kbd/config file specifies:

BLANK_DPMS=on
POWERDOWN_TIME=2

The /etc/init.d/console-screen.kbd.sh script appears to issue a setterm
command with the above options a boot time, yet nothing happens.

I issued the corresponding "setterm" command manually also to no effect.

Is there something that I need to configure in the linux kernel?

Is this a limitation of the frambuffer console with the atyfb driver?

Manually executing "vbetool dpms off" does the trick, so it doesn't look
like this is a hardware limitation per se.

The video card is an ATI Technologies Rage Mobility P/M AGP 2x (rev 64).

Relevant (?) software:

linux-image      :       2.6.26-1-686
acpid            :       1.0.8-1
util-linux       :       2.13.1.1-1
kbd              :       1.14.1-4

Thanks,

CJ.

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