MPC5200 PCI byte-swapping

Sylvain Munaut tnt at
Sun Jan 2 09:39:26 EST 2005

Mark Chambers wrote:

>I've just realized that the 5200 does byte-lane swapping
>on all PCI accesses.  That is, if you write a 32 bit word
>0x12345678, 0x12 will go out on byte 0, 0x34 on byte 1,
>etc.  Unfortunately, my target, a T.I. DM642, does not
>do this, so I've got a big/little endian mismatch.  A couple
>of questions if anybody knows:
>- Do all MPC8xxx processors do this - byte swap on
>all PCI accesses, not just configuration space?
>- Is there an elegant (simple) way to re-swap the bytes?
>It's not a big problem really, but if there were a way to 
>set LE mode on a particular page or something like that
>it might be worth it.
I'm not sure of what you mean but look at the mapping
aroung pdf page 337 of the user manual. It's not configurable
as far as I can see.


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