mach64 EXA bits

[Benjamin Herrenschmidt]

> I don't think there's much configuration regarding swapping at all - 
> the old ATI chips only have a split swapped / non-swapper aperture ( or 
> rather one BE and one LE view )

Well... the swapping on the BE view has to be different for 8, 16 and 32
bpp data so there must be at least some configuration, unless it depends
on what the output is set to... (that would be pretty lame). I need to
dig my mach64 docs and check.

> Or just make sure you use the right view for each one. Not sure if 
> hammering both views at (roughly) the same time would confuse the chip 
> - - might be worth a try but you probably don't have to.

Probably won't but it's not always possible if you try to mix, for
example, 32 and 16 bpp accesses.... Things like DFS/UTS should always
use the LE view imho (provided it's guaranteed that the memcpy
implementation of the platform only ever uses naturally aligned loads
and stores or we'll be screwed too) and we still need to have a proper
PrepareAccess/FinishAccess pair. 

But I'll look into it.

Ben.