[Skiboot] [PATCH] Add NX P7+ support

Stewart Smith stewart at linux.vnet.ibm.com
Tue Mar 17 16:34:30 AEDT 2015

Benjamin Herrenschmidt <benh at au1.ibm.com> writes:
> On Mon, 2015-03-16 at 14:03 -0400, Dan Streetman wrote:
>> Well the kernel driver doesn't care at all about P7/P8 except for the
>> xscom r/w, since the xscom addrs are different between P7/P8.  As I
>> haven't actually added any error recovery (via xscoms) to the kernel
>> driver yet, I could remove the xscom stuff from the first kernel patch
>> set.  However, if the kernel driver is who eventually monitors and
>> handles NX errors, I don't see any way around r/w directly from the NX
>> xscoms.  The P7/P8 differences should be able to be abstracted in the
>> nx-842-xscom.h header though, and I don't think the actual driver will
>> need to know the P num.
> I don't want linux to know about SCOMS, instead, create OPAL calls, for
> example OPAL_GET_NX_STATUS or whatever makes sense for you.
> In any case, a XSCOM is a roundtrip to OPAL so the above won't be
> slower.

I'll merge this patch and possibly disable the 842 DT node creation
before tagging skiboot-5.0 depending on if the patch that adds OPAL
calls arrives in time or not.

(open question: should the protocol for discovering if firmware supports
a thing be "check device tree entry exists and OPAL calls exist" or just
"check device tree" OR check opal call)

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