Could you please try the ati 6.7.196 from https://wiki.ubuntu.com/XorgOnTheEdge ? If possible, also the latest radeon drm module, as they ask in the upstream bug report.
Could you please try the ati 6.7.196 from https:/ /wiki.ubuntu. com/XorgOnTheEd ge ? If possible, also the latest radeon drm module, as they ask in the upstream bug report.