Comment 80 for bug 415023

Please read comment 37, comment 65 and comment 69. The problem has been completely triaged, the MSI Wind handles brightness through the BIOS BUT each change of brightness levels also emits a keypress event which is then handled by gnome-power-manager, powerdevil, or xfce4-power-manager. There are two different problems:

The first issue with this is that each keypress changes brightness twice, resulting effectively in only 4 instead of 8 levels that the hardware is capable of. This is happens with all previous releases of Ubuntu as well.

The second issue is new in 9.10 and has been intoduced with kernel modesetting, that is gnome-power-manager and equivalents start switching back and forth between two adjacent brightness levels either due to a rounding bug or feedback loop (remeber that each time brightness levels are changed in software keypresses are emitted as well).

There is actually a workaround for the second issue (the flickering people report over and over) and that is disabling kernel modesetting by passing nomodeset to the kernel at boot time.

The solution to this problem is that power management software needs to be told that the brightness keys are handled in hardware. In the past this could be done by setting the HAL property laptop_panel.brightness_in_hardware to true as Felix Geyer has pointed out, however this is not read by gnome-power-manager because it handles the backlight through xrandr instead of HAL.