Comment 2 for bug 1510405

According to the upstream developers, support for your hardware in amdgpu is experimental and they do not recommend enabling it. I've prepared a test build with this disabled, which will result in falling back to the radeon driver. Please install the appropriate debs for your architecture from the link below and report back whether or not this resolves your display issues. Thanks!

http://people.canonical.com/~sforshee/lp1510405/