https://bugs.freedesktop.org/show_bug.cgi?id=91880
--- Comment #10 from John Frei johann_frei@yahoo.de --- Wow, thank you for this quick reply!
Here's what i've done now. Please correct me, if I've done something wrong.
//Removing the old ucode. -rm /usr/lib/firmware/radeon/hawaii* -rm /usr/lib/firmware/radeon/HAWAII*
Then I downloaded all 11 files from the link and moved them to /usr/lib/firmware/radeon/.
Finally I executed 'sudo dracut -f' to generate a new initramfs.
Sadly it doesn't change the behavior. I still get a freeze/black screen. :-(