On Thu, Sep 26, 2013 at 11:36:15PM +0100, Andreas Herrmann wrote:

... otherwise it is impossible for the low level iommu driver to
figure out which pte flags should be used.

In __map_sg_chunk we can derive the flags from dma_data_direction.

In __iommu_create_mapping we should treat the memory like
DMA_BIDIRECTIONAL and pass both IOMMU_READ and IOMMU_WRITE to
iommu_map.
__iommu_create_mapping is used during dma_alloc_coherent (via
arm_iommu_alloc_attrs).  AFAIK dma_alloc_coherent is responsible for
allocation _and_ mapping.  I think this implies that access to the
mapped pages should be allowed.

Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andreas Herrmann <redacted>

  Acked-by: Will Deacon [off-list ref]

This one should go via the dma-mapping tree.

Will