On Tuesday 19 August 2014 13:59:54 Joerg Roedel wrote: > 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. Do we have a use case where the unmap_sg() implementation would be different than a plain iommu_unmap() call ? If not I'd rather remove unmap_sg() completely. > > 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. I suggested doing a if (ops is not NULL) return ops(); else return default_ops(); to avoid modifying all drivers. I'm not sure why that wasn't received with much enthusiasm. -- Regards, Laurent Pinchart -- 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
