OpenSUSE brightness control problem on HP ProBook 4740s

Bought an HP ProBook 4740s with SLED 11 , installed OpenSUSE 12.3, brightness control buttons are responsive, but the only effect is that expected brightness level change is displayed with bars, but no actual brightness level change follows. Works in that pre-installed enterprise though.

xbacklight -set

has no effect either

Anyone else has this laptop or just knows the solution?

This thread should ideally go into Laptop forums

Try to add to GRUB these options: “acpi_backlight=vendor acpi_osi=Linux”, and reboot.
It worked for me on HP ProBook 4540s with OpenSUSE 12.3.