[PATCH v2 07/10] ARM: tegra: pcie: Add device tree support

[Bjorn Helgaas]

On Fri, Jun 22, 2012 at 10:53 AM, Arnd Bergmann <arnd at arndb.de> wrote:
> On Friday 22 June 2012, Bjorn Helgaas wrote:
>> The requirement (if there is one) isn't anything related to PC-ness.
>> I just don't understand how things can actually work if two host
>> bridges both claim the same bus number.  If we do a config read to
>> that bus, both bridges should claim it and turn it into config cycles
>> on their respective root buses, and we should get two responses.  I
>> would expect the second response to cause an "unexpected response"
>> machine check or similar.
>
> But each PCI domain has its own config space, so if you do a config
> read for one bus, it's always relative to the domain.

Oh, I see!  I totally missed the fact that each host bridge was in its
own domain.  If each has its own domain, then the bus number aperture
can certainly be [bus 00-ff] and there's no problem.