FreeDesktop.org Bug 78453 remains open about "[HAWAII] Get acceleration working", with new comments coming occasionally from those trying the latest open-source AMD Linux driver on the R9 290/290X hardware and from the upstream developers.
As explained in the earlier article, AMD's open-source developers have commented they have the hardware but that "nobody knows why it doesn't work" and "Hawaii support is not a priority at the moment. We don't have any business cases right now where accelerated open source Hawaii is a priority."
Then again, if you've just spent several hundred dollars on an AMD Radeon R9 290 series graphics card, chances are you'll want to use the Catalyst Linux driver anyways (where the Hawaii support is fine) for maximum performance, OpenGL 4.x support, a fully functional OpenCL compute stack, and other features not currently offered by the open-source driver for any generation of hardware. As soon as the R9 290 series open-source support returns to being functional, we'll be back with more benchmarks.