Created attachment 142156 [details]
dmesg Ubuntu14.04, Kernel4.4.0-133, radeon 2.43.0, screen flickering
... and I found out that the screen-flickering already starts with
VERSION="14.04.5 LTS, Trusty Tahr"
kernel: 4.4.0-133-generic
radeon 2.43.0
see the attached dmesg14.04_4.4.0-133.txt