PCI BAR initialisation..?

Paul Mackerras paulus at samba.org
Thu Jul 12 16:40:18 EST 2001

ashish anand writes:

> But by any chance if somebody has come across a random feature of pci BAR.
> that is if you write the required pci addresses in BAR after writing 0xffffffff and
> reading it back , and to confirm if the actual value has reached the BAR , we read it again
> but then it returns funny values.
> more surprisingly if i move the code in some other function then everything behaves correctly.
> I am more then sure that nothing relevant is happening betwen two places.

Hmmm, that sounds like maybe the config space reads and writes are
getting reordered, which would be a Bad Thing.

What sort of PCI host bridge does your system have?

If you place an mb() call after each pci config read or write, does
that fix the problem?


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