Hi All, Frankly speaking, I didn't follow up this discussion until this point where I wanted to know whether we have iommu ops support in dma-mapping API for 64BIT ARM Arch. If anyone can please provide some more info as what is the current status on this and is it completely supported now ?
Thanks Ritesh On Wed, Jun 19, 2013 at 4:41 PM, Catalin Marinas <[email protected]>wrote: > On Tue, Jun 18, 2013 at 11:08:15PM +0100, Don Dutile wrote: > > On 06/18/2013 08:50 AM, Catalin Marinas wrote: > > > On Tue, Jun 18, 2013 at 12:01:37PM +0100, Hiroshi Doyu wrote: > > >> Arnd Bergmann<[email protected]> 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. > > > > > why not in current drivers/iommu directory ? > > That's not really specific to the iommu driver implementation, they have > a clearly defined interface. For similarity with swiotlb and given that > we already have iommu-helper.c, lib/ looks best to me. Anyway, let's > first see how the code looks like, it can be moved later. > > -- > Catalin > > _______________________________________________ > Linaro-mm-sig mailing list > [email protected] > http://lists.linaro.org/mailman/listinfo/linaro-mm-sig >
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