On July First, after kernek update - kernel188.8.131.52.3-1, powemanagement on my computer stop working correct. In the KDE Control Center - Peripherals - Display _power Control I have checked Enable power...and it works correct to the last update. After update it suspend, power off work but I could't "awake" computer back. Just power button help. I reinstalled kernel184.108.40.206.1-1 today and power management works correct again.
I updated kernel again and I use mkinitcpio now and powermanagement is working correct now.