Re: PCI drivers - memory mapped vs. I/O ports

Alan Cox (alan@lxorguk.ukuu.org.uk)
Mon, 18 Mar 2002 20:32:09 +0000 (GMT)

> If a PCI device can be programmed equally well via I/O port space or memory
> space, what are the reasons to chose one space over the other when writing
> the driver?

mmio is posted on a PC i/o ports are not. That means you have to be more
careful but also means that

write
write
write
read

is a lot faster

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