Created attachment 26599 [details]
dmidecode Output

Hello,

i'm using a Acer Travelmate 6492 Laptop, with i915 Kernel-Mode-Setting. The Backlight control isn't working, neither with the bare kernel nor with loaded acer_wmi module.

Kernel Parameter (tested w/ and w/o): "acpi_backlight=vendor"

What steps will reproduce the problem?
1. modprobe acer_wmi

What is the expected output? What do you see instead?
[ 5553.518046] acer-wmi: Acer Laptop ACPI-WMI Extras
[ 5554.206261] usb 7-1: new full speed USB device using uhci_hcd and address 3
[ 5554.407399] Bluetooth: Generic Bluetooth USB driver ver 0.6
[ 5554.407694] usbcore: registered new interface driver btusb
[ 5554.480212] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[ 5554.480215] Bluetooth: BNEP filters: protocol multicast
[ 5554.491812] Bluetooth: SCO (Voice Link) ver 0.6
[ 5554.491814] Bluetooth: SCO socket layer initialized

No Error Message appears, and the backlight subsystem seems to be present:

# ls -l /sys/class/backlight/acer-wmi/
insgesamt 0
-r--r--r-- 1 root root 4096  1. Jun 09:59 actual_brightness
-rw-r--r-- 1 root root 4096  1. Jun 09:59 bl_power
-rw-r--r-- 1 root root 4096  1. Jun 09:59 brightness
lrwxrwxrwx 1 root root    0  1. Jun 09:59 device -> ../../../acer-wmi
-r--r--r-- 1 root root 4096  1. Jun 08:50 max_brightness
drwxr-xr-x 2 root root    0  1. Jun 09:59 power
lrwxrwxrwx 1 root root    0  1. Jun 08:50 subsystem ->
../../../../../class/backlight
-rw-r--r-- 1 root root 4096  1. Jun 08:50 uevent

But changing the Value in "brightness" doesn't affect anything, nor the Backlight/Brightness Keys will work.

What version of acer_acpi are you using? On which distribution and kernel
version?
2.6.24, Vanilla Kernel and Gentoo patched version

Please provide any additional information below.
see attached dpmidecode, dsdt table, kernel config

Thanks! ;-)

Best Regards, Jay