Re: [PATCH v3 2/2] asm-generic: Add new pci.h and use it

Maciej W. Rozycki
2022-07-22T22:42:17Z

On Fri, 22 Jul 2022, Rob Herring wrote:

> P.S. I really wish I/O space would disappear completely.

Some systems make it happen already, such as the POWER9 platform and its
PHB4 host bridge (which doesn't handle PCIe TLP I/O read or write commands
at all), however some PCI/e devices do require I/O space, such as IEEE
1284 parallel port adapters. Some PCI devices dating back as far as to
1990s provide dual mapping of their resources via an I/O and a memory BAR
both at a time, so we can choose which to use depending on circumstances.

FWIW,

Maciej