Re: remove the ->mapping_error method from dma_map_ops V2
From: Christoph Hellwig <hch@lst.de>
Date: 2018-11-29 18:31:36
Also in:
linux-arch, linux-arm-kernel, linux-iommu, lkml
On Thu, Nov 29, 2018 at 09:44:05AM -0800, Linus Torvalds wrote:
No. Really. If there's no iotlb, then you just mark that one page reserved. It simply doesn't get used. It doesn't mean you suddenly need a swiotlb.
Sure, we could just skip that page entirely based on dma_to_phys.
But whatever. It's independent from the patch series under discussion. Make dma_mapping_error() at least return a real error (eg -EINVAL, or whatever is the common error), and we can maybe do this later.
Ok, I'll do that.
Or, better yet, plan on removing the single-page dma mappign entirely at a later date, and make the issue moot.
What would be the replacement? Build a S/G list for every single page mapping? Not sure that would create a lot of happy campers..