[PATCH 05/16] dma-mapping: Introduce dma_map_sg_p2pdma()

[Christoph Hellwig]

On Tue, Apr 27, 2021 at 08:01:13PM -0300, Jason Gunthorpe wrote:
> At a high level I'm OK with it. dma_map_sg_attrs() is the extra
> extended version of dma_map_sg(), it already has a different
> signature, a different return code is not out of the question.
> 
> dma_map_sg() is just the simple easy to use interface that can't do
> advanced stuff.
> 
> > I'm not that opposed to this. But it will make this series a fair bit
> > longer to change the 8 map_sg_attrs() usages.
> 
> Yes, but the result seems much nicer to not grow the DMA API further.

We already have a mapping function that can return errors:
dma_map_sgtable.

I think it might make more sense to piggy back on that, as the sg_table
abstraction is pretty useful basically everywhere that we deal with
scatterlists anyway.

In the hopefully no too long run I plan to get rid of scatterlists in
at least NVMe and other high performance devices anyway.