[Skiboot] [PATCH 2/2] phb4: set PBCQ Tunnel BAR for tunneled operations

Benjamin Herrenschmidt benh at au1.ibm.com
Tue Nov 14 21:35:57 AEDT 2017

On Tue, 2017-11-14 at 11:29 +0100, Philippe Bergheaud wrote:
> > > The register value indicates which device should receive the tunneled
> > > operation responses. The value of the register must be dynamically
> > > modified by devices to point to their own MMIO range. It cannot be
> > > statically set by skiboot.
> > 
> > Oh so basically we expect a "response" to the device ? That smells like
> > a disgusting HW hack to me ...
> > 
> Yes, limiting tunneled operations to one device per PHB seems strange.
> I have arbitrarily chosen the first-come first-serve policy to cope
> with this limitation.

Ok so I was under the incorrect impression that we were configuring the
address for the requests. That needs to stay in OPAL. For the
responses, I agree, this belongs in the driver, so an OPAL call is
appropriate (which the driver calls via some exported support wrapper).


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