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    SubjectRe: [RFC PATCH] dma: Add barrierless dma mapping/unmapping api
    FUJITA Tomonori wrote:
    > On Tue, 26 Jan 2010 15:30:10 +1100
    > Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
    >
    >> On Mon, 2010-01-25 at 18:35 -0800, adharmap@codeaurora.org wrote:
    >>> From: Abhijeet Dharmapurikar <adharmap@quicinc.com>
    >>>
    >
    >> There are people nowadays putting AXI bridges and the whole ARM
    >> paraphernalia of IP cores behind them on PowerPC cores for example and I
    >> can see that happening with x86 as well.
    >>
    >> In your case, I believe your are fixing the wrong problem anyways. The
    >> right approach would be instead to put all your buffer into an sglist
    >> and use dma_map/unmap_sg().
    >
    > Agreed again. That's exactly what I suggested before:
    >
    > http://marc.info/?l=linux-kernel&m=126294076917753&w=2

    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. I could change those calls to do a barrier
    only after mapping the last buffer. This would be much more cleaner
    than introducing a .*_nobarrier API.

    Thanks for all the replies.



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