Re: SPI TX andRX buffer overlap

[Ned Forrester <nforrester-/d+BM93fTQY@public.gmane.org>]

David Brownell wrote:
> Mapping any number of times *should* be OK -- unless one mapping
> reports an error.  Or you do them in the wrong order (removing
> cache entries before writing their data out to memory).

BINGO!  That was it.  pxa2xx_spi has always done

dma_map_single(..., rx, ..., DMA_FROM_DEVICE)

(thus invalidating the cache) before

dma_map_single(..., tx, ..., DMA_TO_DEVICE)

(thus copying possibly invalid data, if the buffers overlapped).

Thanks, it works now with a much more pleasant patch.  I never looked at
it that way before.  A patch will be coming soon.

-- 
Ned Forrester                                       nforrester-/d+BM93fTQY@public.gmane.org
Oceanographic Systems Lab                                  508-289-2226
Applied Ocean Physics and Engineering Dept.
Woods Hole Oceanographic Institution          Woods Hole, MA 02543, USA
http://www.whoi.edu/sbl/liteSite.do?litesiteid=7212
http://www.whoi.edu/hpb/Site.do?id=1532
http://www.whoi.edu/page.do?pid=10079


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