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Message-ID: <1446002458.1856.25.camel@kernel.crashing.org>
Subject: Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>, Michael Ellerman
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Date: Wed, 28 Oct 2015 12:20:58 +0900
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On Tue, 2015-10-27 at 19:30 -0700, Nishanth Aravamudan wrote:
> On 28.10.2015 [11:20:05 +0900], Benjamin Herrenschmidt wrote:
> > On Tue, 2015-10-27 at 18:54 -0700, Nishanth Aravamudan wrote:
> > > 
> > > In "bypass" mode, what TCE size is used? Is it guaranteed to be
> > > 4K?
> > 
> > None :-) The TCEs are completely bypassed. You get a N:M linear
> > mapping
> > of all memory starting at 1<<59 PCI side.
> 
> Err, duh, sorry! Ok, so in that case, DMA page shift is PAGE_SHIFT,
> then?

I think so.

Cheers,
Ben.