ETC2 Decoding Support In Mesa's Gallium3D For Freedreno

While Intel's implemented ETC2 support in their driver and is supported by their latest hardware, Gallium3D is finally getting some ETC2 support.

Ericsson Texture Compression (ETC) has been popular in the mobile space with ETC1 having been part of OpenGL ES and ETC2/EAC being mandated by OpenGL ES 3.0 and OpenGL 4.3. ETC is much more friendly to open-source enthusiasts than S3 Texture Compression (S3TC) and there's already mainline Mesa support.

Ilia Mirkin, a prolific Nouveau driver contributor to Mesa and who recently has also been working on the Freedreno driver, has been spearheading this ETC2 Gallium3D work. He added basic support to Gallium3D, "No actual decoding is added, similar faking mechanism to bptc."

Mirkin then followed up and added ETC2 to Freedreno for A3xx hardware. With these commits and other code pushed this morning, he also added ARB_instanced_arrays to Freedreno.

Update: Marek at AMD has clarified the changed, "All Gallium drivers have had ETC2 support for 6 months. This is as much as radeon can support. Ilia mainly added the possibility of native ETC2 hardware acceleration for hardware that can do it (not radeon)."