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Date: Wed, 14 Oct 2015 08:39:00 -0700
From: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@linux.intel.com>,
 Keith Busch <keith.busch@intel.com>,
 Benjamin Herrenschmidt <benh@kernel.crashing.org>,
 Paul Mackerras <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>,
 Alexey Kardashevskiy <aik@ozlabs.ru>,
 David Gibson <david@gibson.dropbear.id.au>,
 linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
 linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 1/5 v2] dma-mapping: add generic dma_get_page_shift API
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Hi Christoph,

On 12.10.2015 [14:06:51 -0700], Nishanth Aravamudan wrote:
> On 06.10.2015 [02:51:36 -0700], Christoph Hellwig wrote:
> > Do we need a function here or can we just have a IOMMU_PAGE_SHIFT define
> > with an #ifndef in common code?
> 
> On Power, since it's technically variable, we'd need a function. So are
> you suggesting define'ing it to a function just on Power and leaving it
> a constant elsewhere?
> 
> I noticed that sparc has a IOMMU_PAGE_SHIFT already, fwiw.

Sorry, I should have been more specific -- I'm ready to spin out a v3,
with a sparc-specific function.

Are you ok with leaving it a function for now (the only caller is in
NVMe obviously).

-Nish