In the past month since the release of xf86-video-intel 2.20.0 where SNA acceleration was taken mainstream, Chris Wilson of Intel's Open-Source Technology Center has released four DDX driver point releases in rapid succession.
Chris Wilson personally bundled 56 changes into this 2.20.4 driver update -- most of them concerning his prized "Sandy Bridge New Acceleration" architecture -- while there were a few commits by other developers. Prominent changes to this weekend's driver update is fixing potential errors from using a static code analyzer, an optimization in PolyFillRectangles, removing a UXA warning, fixing the validation of the X-Video pipe parameter, fixing 8x8 tiled-pattern fills, a compile failure in a certain condition, a Gen4 flush fix, and restoring preferred use of the RENDER ring for SNB+ DRI copies. In addition, this driver update features all of the new Intel Haswell variants.
The release announcement for xf86-video-intel 2.20.4 can be found on the X.Org mailing list.