Date: Sat, 24 Jun 2017 09:18:55 +0200
From: Christoph Hellwig <hch@lst.de>
To: tndave <tushar.n.dave@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>, x86@kernel.org,
        linux-arm-kernel@lists.infradead.org, xen-devel@lists.xenproject.org,
        linux-c6x-dev@linux-c6x.org, linux-hexagon@vger.kernel.org,
        linux-ia64@vger.kernel.org, linux-mips@linux-mips.org,
        openrisc@lists.librecores.org, linuxppc-dev@lists.ozlabs.org,
        linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
        sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org,
        dmaengine@vger.kernel.org, linux-tegra@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-samsung-soc@vger.kernel.org,
        iommu@lists.linux-foundation.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: clean up and modularize arch dma_mapping interface V2
Message-ID: <20170624071855.GD14580@lst.de>
References: <20170616181059.19206-1-hch@lst.de> <162d7932-5766-4c29-5471-07d1b699190a@oracle.com>
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On Wed, Jun 21, 2017 at 12:24:28PM -0700, tndave wrote:
> Thanks for doing this.
> So archs can still have their own definition for dma_set_mask() if 
> HAVE_ARCH_DMA_SET_MASK is y?
> (and similarly for dma_set_coherent_mask() when 
> CONFIG_ARCH_HAS_DMA_SET_COHERENT_MASK is y)
> Any plan to change these?

Yes, those should go away, but I'm not entirely sure how yet.  We'll
need some hook for switching between an IOMMU and a direct mapping
(I guess that's what you want to do for sparc as well?), and I need
to find the best way to do that.  Reimplementing all of dma_set_mask
and dma_set_coherent_mask is something that I want to move away from.