In general most -if not all- manufacturers don't give a fuck about linux and the fact that we have this level of support comes down to dedicated hackers that get their hands on the HW. There was a comment by Alan Cox on his G+ page sometime ago that many bugs on the Kernel bugzilla are motherboard/FW bugs and they cannot do anything about it. This is how much they care about linux.
No announcement yet.
AMD Closes The Operating System Research Center