Jerome Glisse sent out a new patch-set concerning HyperZ support for R600g. Jerome wrote, "Ok so this time it should be it. Following patch seems to behave properly. I am still in process of checking again that they don't regress anything, I should be done Monday or Tuesday. If there is no objection by them I will commit them."
It was earlier this year that it was thought HyperZ defeated open-source driver developers for the newer Gallium3D driver. The problems with HyperZ support on the newer Radeon graphics hardware came down to errors within the GPU command stream. Some progress was made after that point with Atom state emission but not much more was heard about R600g HyperZ in recent months.
Jerome Glisse has now stepped up with improvements to R600g HyperZ that he says is yielding 2~10% performance improvements based upon the graphics processor and OpenGL workload while working reliably. The HyperZ feature to ATI/AMD GPU hardware consists of Z compression for minimizing the Z-Buffer bandwidth, fast Z clear, and a hierarchical Z-Buffer.
Jerome's R600g HyperZ patches include reworking the flushing and synchronization pattern to match that of the closed-source Catalyst driver and adding htile for HiZ and HiS support and fast Z/S clears. With these patches the Mesa driver isn't yet taking full advantage of HiS.
These latest R600g HyperZ support patches are currently residing on the mesa-dev list until hopefully being merged to the mainline Mesa repository in the coming days.