[Skiboot] [PATCH skiboot] hw/phb3/naples: Disable D-states

[David Gibson]

On Fri, Jan 11, 2019 at 03:06:52PM +1100, Alexey Kardashevskiy wrote:
> Putting "Mellanox Technologies MT27700 Family [ConnectX-4] [15b3:1013]"
> (more precisely, the second of 2 its PCI functions, no matter in what
> order) into the D3 state causes EEH with the "PCT timeout" error.
> This has been noticed on garrison machines only and firestones do not
> seem to have this issue.
> 
> This disables D-states changing for devices on root buses on Naples by
> installing a config space access filter (copied from PHB4).
> 
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>

While fixing this in firmware seems to make theoretical sense, from
all I can tell it will take an awfully long time to get this merged
into skiboot, built and rolled out to Garrison machines which need it.

I think we also need a kernel side workaround for this for the short
to medium term.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson
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