Messages in this thread |  | | Date | Fri, 7 Dec 2018 07:25:02 -0800 | From | Christoph Hellwig <> | Subject | Re: [PATCH v5 2/2] media: usb: pwc: Don't use coherent DMA buffers for ISO transfer |
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Folks, can you take a look at this tree and see if this is useful for USB:
http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-noncoherent-allocator
The idea is that you use dma_alloc_attrs with the DMA_ATTR_NON_CONSISTENT now that I've made sure it is avaiable everywhere [1], and we can use dma_sync_single_* on it.
The only special case USB will need are the HCD_LOCAL_MEM devices, for which we must use dma_alloc_coherent (or dma_alloc_attrs without DMA_ATTR_NON_CONSISTENT) and must skip the dma_sync_single_* calls, so we'll probably need USB subsystem wrappers for those calls.
[1] except powerpc in this tree - I have another series to make powerpc use the generic dma noncoherent code, which would cover it.
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