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
