Hi Nishanth,
Nishanth Peethambaran nishanth.p@gmail.com wrote @ Thu, 20 Jun 2013 10:07:00 +0200:
It would be better to define a prot flag bit in iommu API and convert the attrs to prot flag bit in dma-mapping aPI before calling the iommu API.
That's the 1st option.
On Thu, Jun 20, 2013 at 11:19 AM, Hiroshi Doyu hdoyu@nvidia.com wrote:
....
@@ -1280,7 +1281,7 @@ ____iommu_create_mapping(struct device *dev, dma_addr_t *req, break;
len = (j - i) << PAGE_SHIFT;
ret = iommu_map(mapping->domain, iova, phys, len, 0);
ret = iommu_map(mapping->domain, iova, phys, len, (int)attrs);Use dma_get_attr and translate the READ_ONLY attr to a new READ_ONLY prot flag bit which needs to be defined in iommu.h
Both DMA_ATTR_READ_ONLY and IOMMU_READ are just logical bit in their layers respectively and eventually it's converted to H/W dependent bit.
If IOMMU is considered as one of specific case of DMA, sharing dma_attr between IOMMU and DMA may not be so bad. IIRC, ARM: dma-mapping API was implemented based on this concept(?).
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index d8f98b1..161a1b0 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -755,7 +755,7 @@ int iommu_domain_has_cap(struct iommu_domain *domain, EXPORT_SYMBOL_GPL(iommu_domain_has_cap);
int iommu_map(struct iommu_domain *domain, unsigned long iova, - phys_addr_t paddr, size_t size, int prot) + phys_addr_t paddr, size_t size, struct dma_attr *attrs) { unsigned long orig_iova = iova; unsigned int min_pagesz;