Re: [PATCH 0/8] dma-mapping: migrate to physical address-based API

Marek Szyprowski
2025-07-08T10:27:18Z

On 30.06.2025 15:38, Christoph Hellwig wrote:
> On Fri, Jun 27, 2025 at 08:02:13PM +0300, Leon Romanovsky wrote:
>>> Thanks for this rework! I assume that the next step is to add map_phys
>>> callback also to the dma_map_ops and teach various dma-mapping providers
>>> to use it to avoid more phys-to-page-to-phys conversions.
>> Probably Christoph will say yes, however I personally don't see any
>> benefit in this. Maybe I wrong here, but all existing .map_page()
>> implementation platforms don't support p2p anyway. They won't benefit
>> from this such conversion.
> I think that conversion should eventually happen, and rather sooner than
> later.

Agreed.

Applied patches 1-7 to my dma-mapping-next branch. Let me know if one
needs a stable branch with it.

Leon, it would be great if You could also prepare an incremental patch
adding map_phys callback to the dma_maps_ops, so the individual
arch-specific dma-mapping providers can be then converted (or simplified
in many cases) too.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland