The patches published today supply libdrm-tegra with a lightweight API on top of the Tegra DRM driver's kernel interfaces. Libdrm is effectively the interface for communication between the kernel DRM drivers and the user-space components (namely the respective X.Org DDX driver and Mesa driver). With the NVIDIA Tegra libdrm support, Thierry Reding has implemented basic EXA 2D acceleration support in the xf86-video-opentegra driver.
That code has also been published today. The patches can be found on the DRI mailing list. This open-source driver supports the NVIDIA Tegra 2/3/4 SoCs and continues maturing thanks to the work by NVIDIA and the open-source community.
The super exciting Tegra K1 SoC also has open-source graphics support but there it's built atop the Nouveau driver since the Tegra K1 integrates a Kepler-based GPU. With future NVIDIA Tegra SoCs now having a common graphics architecture to the desktop, the future of this open-source Tegra/Grate DRM driver is rather limited to existing hardware.