There is no excuse for AMD's binary blob to work with their discrete GPUs - I borrowed a HD7750 and it works ok - but not with their integrated GPU in the A10. Technically it's a 6xxx series GPU slapped on the same die as the CPU cores. It is not an entirely different architecture from outer space.
They can make drivers for Mac OS X that work flawlessly with 6xxx-series cards in iMacs but not for Linux ?