RE: [PATCH 8/9] dspbridge: add map support for big buffers

[FUJITA Tomonori]

On Thu, 26 Aug 2010 07:38:26 -0500
"Guzman Lugo, Fernando" <fernando.lugo@xxxxxx> wrote:

> >> due to a restriction in scatter gather lists, it can
> >> not be created a list for a buffer bigger than 1MB.
> >> This patch is spliting big mappings into 1MB mappings.
> >
> >I don't read the whole thread but the above description is incorrect.
> >
> >Why can't you use scatter gather chaining? You can create a scatter
> >list for a buffer larger than 1MB.
> 
> The thing is that ARM architecture does not support SG chaining. This patch should be
> seen like a workaround until it is fixed in iovmm module.

Fix iovmm module is easier than the workaround?

>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?
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