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

On 05/15/2012 10:46 AM, Thomas Petazzoni wrote:

Le Tue, 15 May 2012 15:32:20 +0000,
Arnd Bergmann [off-list ref] a ?crit :

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Agreed. When looking at the code, I wasn't sure why PCI mappings
were needed so early. Surely, the minimal mappings to get an UART
are quite useful to have very early, but why PCI?

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, as Rob pointed out, we might not need them early, but we
definitely want a fixed address for the PIO window, which ioremap
does not provide.

A fixed address for the PIO window of the PCI registers? Or a fixed
address for the PIO window used to access UART registers?

I would understand why a fixed address is needed for the latter, but
not really for the former.

I'm not sure which PCI registers you mean, but we're talking about PCI
I/O space. The i/o space should be a fixed virtual address so that the
__io() is a constant base for ALL arm platforms. This isn't in place
yet, but that is the plan. Although current macros are constant base.

Rob