Subject: Re: consolidate direct dma mapping and swiotlb support
To: Christoph Hellwig <hch@lst.de>, iommu@lists.linux-foundation.org
Cc: linux-mips@linux-mips.org, linux-ia64@vger.kernel.org,
        linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
        Guan Xuetao <gxt@mprc.pku.edu.cn>, linux-arch@vger.kernel.org,
        linux-s390@vger.kernel.org, linux-c6x-dev@linux-c6x.org,
        linux-hexagon@vger.kernel.org, x86@kernel.org,
        linux-snps-arc@lists.infradead.org,
        adi-buildroot-devel@lists.sourceforge.net, linux-m68k@vger.kernel.org,
        patches@groups.riscv.org, linux-metag@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, Michal Simek <monstr@monstr.eu>,
        linux-parisc@vger.kernel.org, linux-cris-kernel@axis.com,
        linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org
References: <20171229081911.2802-1-hch@lst.de>
From: Vladimir Murzin <vladimir.murzin@arm.com>
Message-ID: <23fee3bb-61ce-1735-b264-3acc0109c858@arm.com>
Date: Fri, 29 Dec 2017 10:52:14 +0000
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On 29/12/17 08:18, Christoph Hellwig wrote:
> Almost every architecture supports a direct dma mapping implementation,
> where no iommu is used and the device dma address is a 1:1 mapping to
> the physical address or has a simple linear offset.  Currently the
> code for this implementation is most duplicated over the architectures,
> and the duplicated again in the swiotlb code, and then duplicated again
> for special cases like the x86 memory encryption DMA ops.
> 
> This series takes the existing very simple dma-noop dma mapping
> implementation, enhances it with all the x86 features and quirks, and
> creates a common set of architecture hooks for it and the swiotlb code.
> 
> It then switches a large number of architectures to this generic
> direct map implement and the new generic swiotlb dma_map ops.
> 
> Note that for now this only handles architectures that do cache coherent
> DMA, but a similar consolidation for non-coherent architectures is in the
> work for later merge windows.

Is it available in your dma-mapping.git or somewhere else?

Cheers
Vladimir

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