On Wed, May 4, 2022 at 2:38 PM Maciej W. Rozycki <macro@xxxxxxxxxxx> wrote:
>
> On Wed, 4 May 2022, Arnd Bergmann wrote:
>
> > Almost all architectures that support CONFIG_PCI also provide
> > HAS_IOPORT today (at least at compile time, if not at runtime),
> > with s390 as a notable exception. Any machines that have legacy
> > PCI device support will also have I/O ports because a lot of
> > legacy PCI cards used it, and any machine with a pc-card slot
> > should also support legacy PCI devices.
> >
> > If we get new architectures without I/O space in the future, they
> > would certainly not care about supporting old cardbus devices.
>
> POWER9 is another architecture with no port I/O space[1]:
POWER9 is just an implementation of the power architecture
that has a particular PCI host bridge. I would assume that
arch/powerpc/ would continue to set HAS_IOPORT because
it knows how to access I/O ports at compile-time.
If a particular host bridge does not declare an I/O port range
in its DT, then of course it won't be accessible, but that is
different from architectures that have no concept of I/O ports.
Arnd
