İ have radeon mobility hd 3470 card , my system is x86_64. Before kernel 3.4.2 i check /sys/class/backlight/ file and i have setting about brightness setting(acpi_video) in this folder and i dont have any problem about brightness. After update my kernel to 3.4.2 or new /sys/class/backlight/ is empty. Ps: i have same problem with both open driver (free) and fglrx driver. My laptop is sony vaio vgn-fw21e. Lspci ; http://paste.kde.org/503558/ Dmesg log ; http://paste.kde.org/502346/ Kernel log; http://paste.kde.org/502340/ My Chakra system; uname -a Linux PC 3.4.2-1-CHAKRA #1 SMP PREEMPT Mon Jun 11 15:21:32 UTC 2012 x86_64 GNU/Linux My Arch system; Linux PC 3.4.3-1-ARCH #1 SMP PREEMPT Mon Jun 18 08:28:29 CEST 2012 x86_64 GNU/Linux
*** This bug has been marked as a duplicate of bug 43168 ***
Patch of Bug 43168 is solve my problem. New kernel of arch linux 3.4.4-2 is have this patch. Thanks.