RE: [PATCH v3 2/2] PCI: Add tango PCIe host bridge support

[David Laight]

> > For my education, what is the API to send an IPI?
> > And the API to handle an IPI?
> 
> There are a few ways you could implement some custom cross-call,
> although in this case I think stop_machine() would probably be the most
> appropriate candidate. However, you're right that in general it may not
> actually help enough to be worthwhile - a DSB SY would ensure that
> in-flight transactions have at least been observed by the CPUs and any
> other coherent masters, but for any writes with a memory type allowing
> early acknowledgement (i.e. a Normal or Device mapping of a BAR) that
> doesn't necessarily correlate with them having reached their ultimate
> destination. For a PCI destination in particular, I think the normal way
> to ensure all posted writes have completed would be to read from config
> space; ah...

He almost certainly doesn't need to wait for the cycle to complete,
just long enough for the cycle to have been sent.

	David