A commit today enables ETC2 hardware support for Stoney. The commit by Marek reads, "radeonsi: add ETC2 support for Stoney. Tested and working."
There's been ETC2 in Gallium3D for Freedreno and Nouveau but up to now there's been no hardware support for ETC2 and within Mesa there is support in the Intel driver.
ETC2 is very promising as an advanced patent-free texture compression algorithm for OpenGL unlike S3TC. Separately work also continues to go into ASTC texture compression as another alternative backed by Khronos. ETC2 codecs are mandatory in OpenGL ES 3.0 and OpenGL 4.3.