Hi,
There's a known failure case. If someone puts in multiple PCI cards that uses more than 2GB of mmio it'll break again.
And what will happen if you need more than 3GiB MMIO space? more than 4GiB? ... you have to set a limit somewhere. And that can be confi- gurable, IMO (It doesn't have to be Kconfig. I'd actually like to see it in the devicetree).
Map the big bars above 4G. Those are typically 64bit bars anyway.
cheers, Gerd