[coreboot] X200 GPU slowdown that needs to be cured by S3

[Artem Mazurov]

Hello. Whenever I try to run any program that uses 3D acceleration
(like glmark2), after a short while performance drops significantly
(From 14 FPS running terrain benchmark to 3 FPS) and persists until
S3.

What could be the problem and how can I troubleshoot this? Since S3
fixes it, maybe it's something with coreboot? cbmem.log attached.