From: Arnd Bergmann <arnd@arndb.de>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [Linaro-mm-sig] [RFC] ARM DMA mapping TODO, v1
Date: Fri, 29 Apr 2011 13:21:16 +0200
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Cc: "Russell King - ARM Linux" <linux@arm.linux.org.uk>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
References: <201104212129.17013.arnd@arndb.de> <20110428131531.GK17290@n2100.arm.linux.org.uk> <1304036754.2513.201.camel@pasglop>
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On Friday 29 April 2011, Benjamin Herrenschmidt wrote:
> 
> > However, dma_alloc_coherent() memory can't be used with the dma_sync_*
> > API as its return address (unlike other architectures) is not in the
> > kernel direct mapped memory range.
> 
> Well, on non-coherent architectures, dma_sync_* are cache flushes, I
> don't see the point of doing those on a non-cachable mapping anyways.
> 
The point was that you cannot do

#define dma_alloc_coherent dma_alloc_noncoherent

on ARM, as some other architectures do.

	Arnd
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