[Patch] PCI/MSI: Handle lack of irqdomain gracefully

[Aaron D. Johnson]

Thomas Gleixner writes:
> Aaron, can you please apply the patch below and see whether it fixes
> the issue and provide the dmesg with the output of those
> pr_warn()'s?

I can build it.  But as stated earlier, the machine is no longer in my
possession.  If it comes back, (and it might -- its new owner is
having problems supplying sufficient input power in his apartment), I
will be happy to test patches.

> The other information which would be useful: When you boot a kernel
> with the commit reverted and look at that OHCI controller with lspci
> -vvv then you should see whether it has MSI enabled or not. If it
> has MSI enabled, then please provide the output of
>
>    /sys/kernel/debug/irq/irqs/$IRQNR
>
> You need to enable CONFIG_GENERIC_IRQ_DEBUGFS for that.

Noted.  And thanks for the time looking into it.

- Aaron