Re: [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance

[Christoph Hellwig]

On Thu, Oct 15, 2020 at 04:43:01PM +0100, Christoph Hellwig wrote:
> > Somewhat related, but is there a way to tell the dma-api to fail instead
> > of falling back to swiotlb? In many case for gpu drivers it's much better
> > if we fall back to dma_alloc_coherent and manage the copying ourselves
> > instead of abstracting this away in the dma-api. Currently that's "solved"
> > rather pessimistically by always allocating from dma_alloc_coherent if
> > swiotlb could be in the picture (at least for ttm based drivers, i915 just
> > falls over).
> 
> Is this for the alloc_pages plus manually map logic in various drivers?
> 
> They should switch to the new dma_alloc_pages API that I'll send to
> Linus for 5.10 soon.

Daniel, can you clarify this?