Laptop Dark Screen Problem

Into The Dark

Did a re-install of Debian on my Fuji laptop last night and pulled down XFCE4 for the desktop. I tried LXDE, which I liked but found it a little buggy. As with most Debian installs, apart from bleeding edge stuff, XFCE4 downloaded and installed flawlessly.

Reboot and the machine is up and running. I have not tried XFCE since the early days when it first hit the streets. Back then, I didn't like the feel much, but it has improved immensely. Looks nice and feels nice.

At first looks, everything seems to work fine. Time will tell.

Next day, first problem on reboot was Laptop LCD display is very dark. Try to adjust using Fn F7 to increase brightness. Nothing. Nada.

Google for a solution. It appears acpi is not working properly and the brightness controls are non-existent. I come across a page with instructions to increase the brightness manually. It suggests as root, do:

echo -n 100 > /proc/acpi/video/VGA/LCD/brightness

In theory, this sets the brightness to 100%.

Only problem on my laptop, this location does not exist. I do an ls of /proc/acpi/video to see whats down there. I get:


Okay that's the video controller. Again I do an ls at /proc/acpi/video/GFX0/ and get:

DD01 DD02 DD03 DD04 DD05 DOS info POST POST_info ROM

I poke around a little more and find settings under /proc/acpi/video/GFX0/DD02/brightness

brightness:levels: 13 25 38 50 63 75 88 100
current: 13

Guess that explains why the screen is so dark. I try the modified command using the /proc settings:

echo -n 100 > /proc/acpi/video/GFX0/DD02/brightness

Brightness goes off the scale. I need sunglasses to look at the screen. Well thats good news of sorts. I try another setting to turn the brightness down.

echo -n 80 > /proc/acpi/video/VGA/LCD/brightness

But this fails. Guess I have to use the pre-sets. I try:

echo -n 88 > /proc/acpi/video/VGA/LCD/brightness

This works but still too bright. I keep trying and finally settle on 50. Halfway but its bright enough in daylight.

So it seems the LCD brightness controls do not presently work in XFCE4 for laptops.

I'll have to do more digging when I have more time.