https://bugs.freedesktop.org/show_bug.cgi?id=67800
--- Comment #7 from Kertesz Laszlo laszlo.kertesz@gmail.com --- Last night i rebooted and re-activated C6 in the BIOS. Reactivated dpms (turn off display completely after 4 minutes).
It the morning (~7 hours of idle time) the computer works as expected. So it seems that those patches solved this issue. I will test it further for anothey day.
As a sideline, sleep state C6 enabled in the BIOS (versus disabled) lowers the idle temperature of the APU by 2-4 C.