Comment 88 for bug 12637

Hi! I'm having similar anoying problem. Don't know if different enough to open a new ticket, but here it is.

When I switch on my laptop (a rebranded ECS laptop with Intel VGA) it's LCD brightness state change as:

1. Right after switching on: full bright (OK)
2. GRUB: full bright (OK)
3. Initng, but when the progress bar is waving from left to right and back: full bright (OK) -- I guess kernel does its initialization here
4. Initng, but when the progress bar resets and start growing as services are started: dims (NOT OK) -- I guess that some service, perhaps ACPI missconfiguration loading, dims the LCD
5. GDM: dimmed (NOT OK)
6. Desktop/GNOME Session: dimmed (NOT OK)

After log in I run a script (as root) with the following line to bring brightness back to a suitable state:

"echo 7 > /sys/class/backlight/acpi_video0/brightness"

Although another way to get the same result would be:

"echo 100 > /proc/acpi/video/GFX0/DD03/brightness"

These bring brightness back to normal. But, after running any SDL application, like 'dosbox', the LCD dims again, so I have to re-run the above commands. So, I ran some more tests, they are:

6.1. Desktop/GNOME Session, SDL 'dosbox': dims (NOT OK)
6.2. Desktop/GNOME Session, my own SDL application: dims (NOT OK)

Running the afore mentioned 'echoes' brings the brightness back to normal.

6.3. Desktop/GNOME Session, Screensaver: full bright (OK)
6.4. Desktop/GNOME Session, Suspend: full bright (OK)
6.5. Desktop/GNOME Session, Hibernate: full bright (OK)

Some more details about my system:
* Ubuntu Hardy 8.04
* PCI VGA Controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (rev 03)
* Function keys for LCD brightness: they don't work, but I'm not concerned about them by now
* Kernel 2.6.24-19-generic

MY POINTS OF INVESTIGATION:
* Why LCD dims at boot, apparently at services loading time?
* Why the start of a SDL based application dims LCD?
* Screensaver, suspending and hibernating cause no problem

REMAINING TESTS:
* ACPI boot parameter "acpi_apic_instance=2" (as pointed in boot messages)
* ACPI boot parameter "acpi_osi=Linux" (as pointed in boot messages)
As soon as I learn on how to use them with GRUB+initng.

I'm attaching some logging files which may be helpful for debugging. Take some time looking at the 'ACPI Error' messages at 'dmesg.txt' and 'kern.log'.