What are the contents of /sys/class/backlight/acer-wmi/max_brightness?
With the acer_wmi interface, can you now try:
Code:
sudo setpci -s 00:02.0 F4.B=ff
sudo setpci -s 00:02.0 F4.B=7f
sudo setpci -s 00:02.0 F4.B=00
...to see if there is any change to the brightness.
Also try:
Code:
xbacklight -set 50
xbacklight -set 100
...you may need to install xbacklight from the repositories.
And finally, do you now have a /sys/devices/platform/acer-wmi/backlight/acer-wmi/? Are there brightness files there and can you force a brightness change.
If you have this working with the external monitor plugged in and the lcd off, the brightness controls might not work. Try adding:
Code:
echo 10 > /sys/class/backlight/acer-wmi/brightness
into your /etc/rc.local file (before the exit 0) and rebooting without the external monitor plugged in.
Another option might be to install openssh-server so that you can ssh from another machine and try adjusting the brightness controls remotely (instead of rebooting all the time)
EDIT: One more thing to try - try booting with the following kernel parameters:
Code:
acpi_osi=Linux acpi_backlight=vendor
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