Panic in quirk_usb_early_handoff

[David Laight]

From: Mason
> Sent: 06 March 2017 13:50
> On 06/03/2017 13:42, Mason wrote:
> 
> > So the kernel panics in xhci_find_next_ext_cap()
> > ( drivers/usb/host/xhci-ext-caps.h:122 )
> > http://lxr.free-electrons.com/source/drivers/usb/host/xhci-ext-caps.h?v=4.9#L122
> >
> > Any idea how this can happen?
> >
> > 	base = ioremap_nocache(pci_resource_start(pdev, 0), len);
> >
> > Could I be passing garbage to ioremap_nocache?
> 
> Oh...
> 
> I have just now understood what Ard wrote a few days ago.
> 
> The issue was that, on this platform, the PCI configuration space
> and memory space are multiplexed; in other words they reside at
> the same physical address, with a bit in MMIO to choose one or
> the other.

Time to shoot another hardware engineer.
Hopefully it isn't an SMP system - but I wouldn't put it past them.

	David