[PATCH v8 3/9] pci: Introduce pci_register_io_range() helper function.

On Wed, Jul 9, 2014 at 12:20 AM, Arnd Bergmann [off-list ref] wrote:

On Tuesday 08 July 2014, Bjorn Helgaas wrote:

quoted

I think my confusion is because your pci_register_io_range() and
pci_addess_to_pci() implementations assume that every io_range starts at
I/O port 0 on PCI (correct me if I'm wrong).  I suspect that's why you
don't save the I/O port number in struct io_range.

I think you are just misreading the code, but I agree it's hard to
understand and I made the same mistake in my initial reply to the
first version.

pci_register_io_range and pci_address_to_pci only worry about the mapping
between CPU physical and Linux I/O address, they do not care which PCI
port numbers are behind that. The mapping between PCI port numbers and
Linux port numbers is done correctly in patch 8/9 in the
pci_host_bridge_of_get_ranges() function.

Ah, I see now.  Thanks for explaining this again (I see you explained
it earlier; I just didn't understand it).  Now that I see it, it *is*
very slick to handle both MMIO and PIO spaces the same way.

Bjorn