https://bugs.freedesktop.org/show_bug.cgi?id=90278
--- Comment #1 from emilio.moretti@gmail.com --- Same here. Ubuntu 15.04. Radeon HD 7770 1GB. CPU: AMD FX6100. I'm running the amd64 Ubuntu release.
As I said in the other report. The last message I see is: (WW) RADEON(0): radeon_dri2_flip_event_handler: Pageflip completion event has impossible msc XXXXXXX < target_msc XXXXXX
no other messages found in any log. The driver is correctly installed. All binary drivers were previously uninstalled like this:
1) sudo apt-get purge "fglrx*"
2) dpkg -l '*fglrx*'
3) dpkg --purge <all listed packages>
4) locate fglrx Manually removed all existing references to the binary drivers.
5) sudo apt-get install --reinstall xserver-xorg-core libgl1-mesa-glx:i386 libgl1-mesa-dri:i386 libgl1-mesa-glx:amd64 libgl1-mesa-dri:amd64
6) sudo dpkg-reconfigure xserver-xorg