HyperZ, MSAA Get Some Fixes In R300 Gallium3D

In addition to killing the Xorg R300g state tracker target, on Sunday Marek Olšák pushed a number of other changes into the vintage "R300g" open-source graphics driver.

Marek's other changes for the R300g driver on Sunday are noteworthy in that they bring fixes as it concerns the HyperZ/HiZ and MSAA support. Marek's fixes that he pushed yesterday for these important features were:

- r300g: fix MSAA resolve to an untiled texture
- r300g: advertise MSAA support for the RGB10_A2 format on r500
- r300g: allow separate depth and stencil clear
- r300g: if both Z and stencil are present, they must be fast-cleared together
- r300g: allow HiZ with a 16-bit zbuffer
- r300g: random hyperz cleanups

As always, the list of Mesa changes can be found from the Mesa CGit log.

HyperZ/HiZ is very important since it allows for some notable OpenGL performance improvements. As of last month, R300g HyperZ was finally flipped on, but initially just for the Radeon X1000 (R500) graphics cards. As a result, in December I did publish new AMD HyperZ Linux benchmarks from this open-source driver.

Aside from the R300g HyperZ support to fix long-standing issues, the HyperZ support in R600g was also improved to better this performance-enhancing feature for newer AMD Radeon GPUs.

MSAA support also recently came about and is still being improved in the Radeon Gallium3D drivers. Unfortunately, the MSAA anti-aliasing performance is awful on the already performance-troubled open-source driver.