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SubjectRe: dma_unmap_single() lacking cache sync on some archs?
[Resending with CC to affected parties]

Hi,

I would expect cache synchronization for DMA_TO_DEVICE and DMA_BIDIRECTIONAL
when dma_map_single() is called, and for DMA_FROM_DEVICE and DMA_BIDIRECTIONAL
when dma_unmap_single() is called.

However, on some architechtures (at least avr32, blackfin, ...), cache
synchronization only happens when dma_map_single() is called (and then
irrespective of DMA direction). dma_unmap_single() is a no-op for these archs.

See e.g. http://lxr.linux.no/#linux+v3.0.4/arch/avr32/include/asm/dma-mapping.h#L117

Isn't this a bug?

(Please CC me in responses.)

--
Arvid Brodin
Enea Services Stockholm AB



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