Messages in this thread | | | Date | Thu, 26 Aug 2010 23:03:01 +0900 | Subject | RE: [PATCH 8/9] dspbridge: add map support for big buffers | From | FUJITA Tomonori <> |
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On Thu, 26 Aug 2010 08:16:24 -0500 "Guzman Lugo, Fernando" <fernando.lugo@ti.com> wrote:
> >From a quick look, arch/arm/plat-omap/iovmm.c does nothing wrong about > >scatter gather chaining. arm/arm/mm/dma-mapping.c looks fine too about > >it. Maybe just defining ARCH_HAS_SG_CHAIN works? > > I can try, but it looks tricky for me. Maybe someone else can tell us why > SG chain is not supported for ARM or if there is a problem just defining > ARCH_HAS_SG_CHAIN.
I suppose that nobody in ARM has been interested in the feature. It was invented to improve I/O performance with large I/O requests. No wonder embeded people aren't interested in it.
fujita@rose:~/git/linux-2.6$ find arch -name 'scatterlist.h'|xargs grep HAS_SG arch/x86/include/asm/scatterlist.h:#define ARCH_HAS_SG_CHAIN arch/ia64/include/asm/scatterlist.h:#define ARCH_HAS_SG_CHAIN arch/sparc/include/asm/scatterlist.h:#define ARCH_HAS_SG_CHAIN arch/powerpc/include/asm/scatterlist.h:#define ARCH_HAS_SG_CHAIN
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