[ltp] IBM T42 (Radeon Mobility 7500) display backlight question

[Cougar]

Hi,

I wrote to both ThinkPad ACPI and radeontool autors but maybe even in this 
list can aswer to this question..

When closing laptop lid it switches off display backlight but not a 
display itself (with good light like sunlight you can still see the 
picture). radeontool can help here to switch off video to save more power 
(can be controlled used ACPI events).

Here I made also some tests how much my laptop eats battery with different 
display usage. The difference is quite big.

video off       14178 mW
lid closed      15416 mW
light min       16385 mW
light max       19111 mW

My question is a little bit different. I'd like to switch backlight 
completely off but keep video running like it happens when lid is closed. 
I found that using colors with big contrast difference like black and 
white it is possible to work with bright sunlight without any problems.
for that backlight is not needed and switching it off can save some power.

So, is it possible to do the same that closing lid does? This can save 
power about 6-7% and this is big number when running laptop at the beach 
:-)

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Cougar