I have the same problem on my acer Extensa 5230 notebook with intel driver 2.9 and kernel 2.6.31.
Without KMS, "xrandr --props" shows properties "BACKLIGHT" and "BACKLIGHT_CONTROL", while with KMS, there are the properties "BACKLIGHT" and "Backlight", but no "BACKLIGHT_CONTROL". Setting brightness via xrandr or /sys/class/backlight both work with KMS, only the keys have no effect.
The acer Extensa 5230 has no "brightness" menu point in its BIOS.
I have the same problem on my acer Extensa 5230 notebook with intel driver 2.9 and kernel 2.6.31.
Without KMS, "xrandr --props" shows properties "BACKLIGHT" and "BACKLIGHT_ CONTROL" , while with KMS, there are the properties "BACKLIGHT" and "Backlight", but no "BACKLIGHT_ CONTROL" . Setting brightness via xrandr or /sys/class/ backlight both work with KMS, only the keys have no effect.
The acer Extensa 5230 has no "brightness" menu point in its BIOS.