Samsung NP300 laptop's brightness control problem

[roansh]

I am using Fedora 17 x86_64

After kernel upgrade, brightness control keys (Fn+F2, Fn+F3) are not working. Screen flickers while trying to
change the brightness but it doesn't get changed.
Old kernel was : 3.3.X
the new kernel is : 3.4.Y

However, on old kernel, I'd given acpi_backlight=vendor acpi_osi=linux kernel parameter, to make it work.
But, that doesn't work anymore.