OpenCL on Ubuntu (Gnome, 16.04) on MacPro 6.1 "FirePro D300". Which driver?

Discussion created by frankj. on Nov 22, 2016
Latest reply on Dec 14, 2016 by ray_m

I want to work with "Darktable" which uses "OpenCL" on Ubuntu (Gnome, 16.04) on a MacPro 6.1 (late 2013, "Ashtray").

It has  "Dual AMD FirePro D300" Graphic-Cards.

Which driver should I install?
I can't find "FirePro D300" on the Download-Site.
By default Ubuntu's radeon-driver is installed. OpenCL seems not to be supported.

"apt-get install amdgpu-pro" shows conflicts (can't overwrite a file) and left (with -f = force)  the system unbootable before login (dark screen with flickering messages any few seconds).

Is FirePro D300 supported by amdgpu-pro?