[PATCH v3 07/17] dma-mapping: Implement link/unlink ranges API

[Jason Gunthorpe]

On Tue, Nov 19, 2024 at 03:57:43PM +0200, Leon Romanovsky wrote:

> > > dma_iova_link/dma_iova_unlink() don't have any assumptions in addition
> > > to already existing for dma_map_sg/dma_unmap_sg(). In reality, it means
> > > that all calls to unlink will have same size as for link.
> > 
> > Ok, great. Any chance you could call that out in the documentation patch,
> > please?
> 
> Can you suggest what should I add there, as it is not specific to new
> API, but general note applicable to all __iommu_unmap() callers?

This is what I wrote:

+/**
+ * iommu_unmap() - Remove mappings from a range of IOVA
+ * @domain: Domain to manipulate
+ * @iova: IO virtual address to start
+ * @size: Length of the range starting from @iova
+ *
+ * iommu_unmap() will remove a translation created by iommu_map(). It cannot
+ * subdivide a mapping created by iommu_map(), so it should be called with IOVA
+ * ranges that match what was passed to iommu_map(). The range can aggregate
+ * contiguous iommu_map() calls so long as no individual range is split.
+ *
+ * Returns: Number of bytes of IOVA unmapped. iova + res will be the point
+ * unmapping stopped.
+ */

Jason