From: catalin.marinas@arm•com (Catalin Marinas)
To: linux-arm-kernel@lists•infradead.org
Subject: DMA mapping API(IOMMU) for ARM64?
Date: Tue, 18 Jun 2013 13:50:54 +0100 [thread overview]
Message-ID: <20130618125054.GL9930@arm.com> (raw)
In-Reply-To: <20130618.140137.1551430695673122122.hdoyu@nvidia.com>
On Tue, Jun 18, 2013 at 12:01:37PM +0100, Hiroshi Doyu wrote:
> Arnd Bergmann <arnd@arndb•de> wrote @ Tue, 18 Jun 2013 12:32:44 +0200:
> > On Tuesday 18 June 2013 11:19:14 Will Deacon wrote:
> > > I've spoken briefly with Catalin about this and it seems like there might be
> > > *some* scope for sharing common dma-mapping code between architectures.
> > > There doesn't really need to be any architecture-specific details in
> > > allocating iova space and the interface to the iommu drivers is
> > > well-defined. The arch-specific stuff is bogged down in the non-coherent
> > > buffer management, but that doesn't necessarily equate to lots of code.
> > >
> > > So, the best bet would be to figure out how to split up what we have under
> > > arch/arm/ so that it can be re-used by arm64 and potentially other
> > > architectures (powerpc has some simple stuff for coherent mappings and some
> > > less-simple stuff for non-coherent buffers).
> >
> > I'm sure that other architectures are interested in sharing the code.
> > Best move it into the global mm/ directory, at least the version for
> > coherent mappings.
>
> I'm guessing that this kind of unification usually takes some time
> since we need to factor out the common code from the different
> ${ARCH}/mm/dma-mapping.c. Also some of ${ARCH} has IOMMU support in
> it. So if we want to develop our 64-bit ARM with working DMA mapping
> API during this transition, the step to take would be:
>
> 1, Copy arch/arm/mm/dma-mapping.c arch/arm64/mm/dma-mapping.c(+swiotlb)
> 2, Adapt arch/arm64/mm/dma-mapping.c(+swiotlb) to 64bit compatible.
> 3, Factor out the common code from them into mm/dma-mapping.c
Or add the relevant code to something like lib/iommu-helper.c, convert
arm64 to use that and we can work on converting arm and other
architectures afterwards.
--
Catalin
next prev parent reply other threads:[~2013-06-18 12:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-18 2:39 DMA mapping API(IOMMU) for ARM64? Hiroshi Doyu
2013-06-18 10:19 ` Will Deacon
2013-06-18 10:32 ` Arnd Bergmann
2013-06-18 10:38 ` Catalin Marinas
2013-06-18 11:01 ` Hiroshi Doyu
2013-06-18 12:50 ` Catalin Marinas [this message]
2013-06-18 14:15 ` Arnd Bergmann
2013-06-18 15:20 ` Hiroshi Doyu
2013-06-18 22:08 ` Don Dutile
2013-06-19 11:11 ` Catalin Marinas
2013-06-19 9:29 ` Marek Szyprowski
2013-06-18 12:51 ` Arnd Bergmann
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