On 06/01/2022 18:14, Bjorn Helgaas wrote:

quoted

That driver would prob not be used on systems which does not support PIO,
and so could have a HAS_IOPORT dependency. But it is not strictly necessary.

I don't want the path of "this driver isn't needed because the device
is unlikely to be used on this arch."

Sure, that was just a one off example. As I mentioned before, I think 
that Arnd already did most of the ifdeffery work, but it was not 
included in this series.

Maybe it's not_always_  possible, but if the device can be plugged
into the platform, I think we should be able to build the driver for
it.

If the device requires I/O port space and the platform doesn't support
it, the PCI core or the driver should detect that and give a useful
diagnostic.

I'm not sure what the driver can say apart from -ENODEV. Or IO port 
management in resource.c could warn for requesting IO port region when 
it's unsupported.

Anyway, this same conversion was had with Linus before I got involved. 
If you think it is worth discussing again then I suppose the authors 
here need to gain consensus.

Thanks,
John