From: Arnd Bergmann <arnd@arndb.de>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Subject: Re: [PATCH] asm-generic: add dma-mapping-linear.h
Date: Mon, 1 Jun 2009 11:28:09 +0100
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Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
       linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
References: <200905282104.55818.arnd@arndb.de> <20090601170847V.fujita.tomonori@lab.ntt.co.jp> <20090601082943.GA5550@flint.arm.linux.org.uk>
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On Monday 01 June 2009, Russell King wrote:
> On Mon, Jun 01, 2009 at 05:08:09PM +0900, FUJITA Tomonori wrote:
> > This adds a version of the dma-mapping API to asm-generic that can be
> > used by most architectures that only need a linear mapping.
> 
> It depends what is meant by "linear mapping".
> 
> If that's just a way of saying "all that needs to be done for the
> DMA streaming APIs is to flush the cache" then the vast majority of
> ARMs fall into that category.

Right. You can probably split out the arm dma-mapping.h implementation
into the dmabounce version and a version that falls back to my
asm-generic code.

One feature that the arm code currently has that I'm still missing is
highmem support, which seems to be relatively complex in arm
(three different implementations). Not sure how to best fit that in there.

	Arnd <><
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