On Mon, Aug 18, 2014 at 03:47:56PM -0700, Olav Haugan wrote: > If the alignment is not correct then iommu_map() will return error. Not > sure what other option we have here (and why make it different behavior > than iommu_map which just return error when it is not aligned properly). > I don't think we want to force any kind of alignment automatically. I > would rather have the API tell me I am doing something wrong than having > the function aligning the values and possibly undermap or overmap. But sg->offset is an offset into the page (at least it is used that way in the DMA-API and since you do 'page_len = s->offset + s->length' you use it the same way). So when you pass iova + offset the result will no longer be page-aligned. You should force sg->offset == 0 and sg->length to be page-aligned instead. This makes more sense because the IOMMU-API works on (io)-page granularity and not on arbitrary phys-addr ranges like the DMA-API. > Yes, I am aware of that. However, several people prefer this than > passing in scatterlist. It is not very convenient to pass a scatterlist > in some use cases. Someone mentioned a use case where they would have to > create a dummy sg list and populate it with the iova just to do an > unmap. I believe we would have to do this also. There is no use for > sglist when unmapping. However, would like to keep separate API from > iommu_unmap() to keep the API function names symmetric (map_sg/unmap_sg). Keeping it symetric is not more complicated, the caller just needs to keep the sg-list used for mapping around. I prefer the unmap_sg call to work in sg-lists too. > I thought that was why we added the default fallback and set all the > drivers to point to these fallback functions. Several people wanted this > so that we don't have to have NULL-check in these functions (and have > the functions be simple inline functions). Okay, since you add these call-backs to all drivers I think I can live with not doing a pointer check here. Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
