From: Michael Ellerman <mpe@ellerman.id.au>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Nishanth Aravamudan <nacc@linux.vnet.ibm.com>,
Alistair Popple <alistair@popple.id.au>,
Anton Blanchard <anton@samba.org>,
Gavin Shan <gwshan@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
Alexander Graf <agraf@suse.de>
Subject: Re: [PATCH] powerpc/iommu/ddw: Fix endianness
Date: Mon, 15 Sep 2014 19:18:08 +1000 [thread overview]
Message-ID: <1410772688.3931.0.camel@concordia> (raw)
In-Reply-To: <5416A64E.1060005@ozlabs.ru>
On Mon, 2014-09-15 at 18:41 +1000, Alexey Kardashevskiy wrote:
> On 09/09/2014 09:22 PM, Alexey Kardashevskiy wrote:
> > rtas_call() accepts and returns values in CPU endianness.
Sounds right.
> > of_read_number() accepts big-endian values but create.addr_hi/lo returned
> > by rtas_call() are in CPU endiannes.
Also sounds right.
> > The dynamic_dma_window_prop struct defines all members as BE so let's
> > make it true.
It does. But why does it do that? It seems to be allocated and setup in
enable_ddw() and then the only place I see it used is in
tce_setrange_multi_pSeriesLP()/tce_clearrange_multi_pSeriesLP(), which both
unpack it again. What am I missing?
> > struct dynamic_dma_window_prop {
> > __be32 liobn; /* tce table number */
> > __be64 dma_base; /* address hi,lo */
> > __be32 tce_shift; /* ilog2(tce_page_size) */
> > __be32 window_shift; /* ilog2(tce_window_size) */
> > };
We do read them from the device tree in find_existing_ddw_windows(), but if
that's the only place then the conversion to cpu endian should happen there.
> > diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> > index 7c1d77c..700020a 100644
> > --- a/arch/powerpc/platforms/pseries/iommu.c
> > +++ b/arch/powerpc/platforms/pseries/iommu.c
> > @@ -750,7 +750,7 @@ static void remove_ddw(struct device_node *np, bool remove_prop)
> > pr_debug("%s successfully cleared tces in window.\n",
> > np->full_name);
> >
> > - ret = rtas_call(ddw_avail[2], 1, 1, NULL, liobn);
> > + ret = rtas_call(be32_to_cpu(ddw_avail[2]), 1, 1, NULL, liobn);
The conversion should happen once where ever ddw_avail comes out of the device
tree, rather than everywhere it's used.
cheers
next prev parent reply other threads:[~2014-09-15 9:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-09 11:22 [PATCH] powerpc/iommu/ddw: Fix endianness Alexey Kardashevskiy
2014-09-15 8:41 ` Alexey Kardashevskiy
2014-09-15 9:18 ` Michael Ellerman [this message]
2014-09-15 10:26 ` Alexey Kardashevskiy
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