[PATCH 08/28] MIPS: make dma_sync_*_for_cpu a little less overzealous

[Thomas Bogendoerfer]

On Wed, Aug 19, 2020 at 08:55:35AM +0200, Christoph Hellwig wrote:
> When transferring DMA ownership back to the CPU there should never
> be any writeback from the cache, as the buffer was owned by the
> device until now.  Instead it should just be invalidated for the
> mapping directions where the device could have written data.
> Note that the changes rely on the fact that kmap_atomic is stubbed
> out for the !HIGHMEM case to simplify the code a bit.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>  arch/mips/mm/dma-noncoherent.c | 44 +++++++++++++++++++++-------------
>  1 file changed, 28 insertions(+), 16 deletions(-)

Acked-by: Thomas Bogendoerfer <tsbogend at alpha.franken.de>

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good idea.                                                [ RFC1925, 2.3 ]