From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Frederic Barrat <fbarrat@linux.vnet.ibm.com>,
mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org,
mikey@neuling.org, brking@linux.vnet.ibm.com,
clsoto@linux.vnet.ibm.com
Subject: Re: [PATCH v2] powerpc/powernv: Enable PCI peer-to-peer
Date: Thu, 13 Jul 2017 10:25:53 +1000 [thread overview]
Message-ID: <1499905553.2865.49.camel@kernel.crashing.org> (raw)
In-Reply-To: <040bff3c-6afd-0e20-2d3c-d26716137eeb@linux.vnet.ibm.com>
On Wed, 2017-07-12 at 18:01 -0500, Frederic Barrat wrote:
> > So you have the initiator refcounting in Linux and the target
> > refcounting in OPAL ... any reason for that ?
>
> The initiator refcount is per PE and skiboot doesn't track PEs. Also
> when the initiator refcount falls back to 0, we should restore the
> default bypass setting for the TVE, and that's more easily done from
> linux, since it knows the start and end address of the memory. So for
> those reasons, I don't really have the choice, the initiator refcount
> seems better suited in linux.
>
> The target refcount is per PHB and it just seemed easier to keep it in opal.
>
> Does the lack of symmetry bother you?
Only mildly. I would have put the whole refcount in Linux...
Cheers,
Ben.
prev parent reply other threads:[~2017-07-13 0:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-26 18:08 [PATCH v2] powerpc/powernv: Enable PCI peer-to-peer Frederic Barrat
2017-06-27 12:32 ` David Laight
2017-06-27 18:52 ` Frederic Barrat
2017-07-12 22:39 ` Benjamin Herrenschmidt
2017-07-12 23:01 ` Frederic Barrat
2017-07-13 0:25 ` Benjamin Herrenschmidt [this message]
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