Freedreno Driver Gains Qualcomm A3XX Support

Freedreno, the reverse-engineered community-based open-source driver for Qualcomm Adreno graphics hardware, now has support for the newer A300 series of graphics cores as found in the Google Nexus 4.

After Freedreno gained XA acceleration support to accelerate 2D operations over Gallium3D, Rob Clark of Freedreno got his driver up and running on the Google Nexus 4 smart-phone with the A320 GPU.

Rob explains in his commit message:

The adreno a3xx GPU is found in newer snapdragon devices, such as the nexus4. The a3xx is GLESv3 and OpenCL capable, although that is not enabled yet in gallium.

Compared to a2xx, it introduces an entirely new unified shader ISA, and re-shuffles all or nearly all of the registers. The good news is that (for the most part) the registers are more orthogonal, not combining unrelated state in a single register. And that there is a lot more flexibility, so we don't need to patch and re-emit the shader like we did on a2xx.

The shader compiler is currently quite dumb, there would be a lot of room for improvement with an optimizing pass. Despite that, with the a320 in my nexus4 it seems to be ~2-3x faster compared to the a220 in my HP touchpad.