Setting brightness level on HP EliteBook 8460p is not working. I tried these commans: # cat /sys/class/backlight/acpi_video0/max_brightness 20 # cat /sys/class/backlight/acpi_video0/brightness 20 # echo 0 > /sys/class/backlight/acpi_video0/brightness # cat /sys/class/backlight/acpi_video0/brightness 0 # echo 20 > /sys/class/backlight/acpi_video0/brightness # cat /sys/class/backlight/acpi_video0/brightness 20 It did not show me any error, but screen brightness was not changed. And setting brightness with Fn keys does not working (xev see scancodes, but nothing happened). When I disabled ACPI (with acpi=off in grub) brightness keys started working, but xev does not see scancodes. And all other Fn keys does not working (when acpi is disabled). And it is possible to change brightness (with Fn keys) in Grub. But when linux kernel is loaded (with enabled acpi) brightness keys stop working.
The problem has not been fixed yet, right? please attach the acpidump output of this laptop.
Created attachment 72105 [details] acpidump
More info is here: http://www.mail-archive.com/platform-driver-x86@vger.kernel.org/msg02862.html Brightness control maybe need to be implemented in radeon driver... *** This bug has been marked as a duplicate of bug 40862 ***