Re: [PATCH 2/3] riscv: Implement Zicbom-based cache management operations

Heiko Stübner
2022-06-17T08:31:11Z

Am Donnerstag, 16. Juni 2022, 14:11:57 CEST schrieb Christoph Hellwig:
> On Thu, Jun 16, 2022 at 02:09:47PM +0200, Heiko Stübner wrote:
> > My guess was that new platforms implementing cache-management will want
> > to be non-coherent by default?
>
> No. Cache incoherent DMA is absolutely horrible and almost impossible
> to get right for the corner cases. It is a cost cutting measure seen on
> cheap SOCs and mostly avoided for more enterprise grade products.

ok, then we'll do it the other way around as suggested :-) .
Coherent by default and marking the non-coherent parts.

DT people on IRC yesterday were also open to adding a dma-noncoherent
property for that case.

Heiko