# Re: \[PATCH 08/28\] MIPS: make dma\_sync\_\*\_for\_cpu a little less overzealous

- From: Thomas Bogendoerfer \<tsbogend@alpha.franken.de\>
- Date: 2020-09-01 14:01:52 
- List: netdev
- Page: https://ratatoskr.run/netdev/2020/09/6089506
- Thread: https://ratatoskr.run/linux-doc/2020/08/6073543/t.md

```text
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@lst.de>
> ---
>  arch/mips/mm/dma-noncoherent.c | 44 +++++++++++++++++++++-------------
>  1 file changed, 28 insertions(+), 16 deletions(-)

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

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]
```