https://bugs.freedesktop.org/show_bug.cgi?id=108317
--- Comment #14 from John Galt johngaltfirstrun@gmail.com --- It would seem that there was only ever one or two reports of this working on Polaris, and they're probably either fake or incorrect for other reasons (like running amdgpu-pro and not realizing).
Unfortunately this means that Polaris probably never worked here.