[PATCH 6/8] arm: mach-armada: add support for Armada XP board with device tree

On Tue, May 15, 2012 at 04:07:59PM +0100, Ben Dooks wrote:

I think it was because that PCI was initialised early and requires a
large mapping space. It is very likely to be legacy kernel stuff that
people have kept copying through.

No.  PCI needs nothing other than access to the configuration space, and
the PCI IO window.  There has _never_ been any hard requirement to map
PCI memory in map_io() because that is _always_ done by drivers calling
ioremap().

There is one exception to this: if you have a VGA card in a PCI slot,
it appears by default as an ISA peripheral with the VGA memory
appearing at around PCI_MEM_BASE + 640K or so.  Linux expects that
to already be mapped.

If you're not supporting VGA cards in text mode, that detail doesn't
concern you.