Re: [RFC PATCH] dma: Add barrierless dma mapping/unmapping api

From: Benjamin Herrenschmidt
Date: Wed Jan 27 2010 - 01:51:18 EST


On Wed, 2010-01-27 at 14:19 +0900, FUJITA Tomonori wrote:
> > I somehow missed your post, my apologies. Agreed that
> dma_map/unmap_sg
> > would be the correct api to use here, however they still call the
> > dmac_.*_range to map buffers.
>
> Hmm, sounds like arm's implementation issue. dma_map_sg API doesn't
> require such. dma_map_sg API gives what you want, do a sync only after
> mapping the last buffer.

dmac_* appears to be ARM's low-level ops for cache flushing on
non-coherent DMA, so it's really down to arch stuff here and how ARM
implements dma_[un]map_sg() and we keep a sane global driver API.

Cheers,
Ben.


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