Hi Kyungmin,
Kyungmin Park <kmpark@xxxxxxxxxxxxx> wrote @ Thu, 20 Jun 2013 08:50:14 +0200:
> On Thu, Jun 20, 2013 at 2:49 PM, Hiroshi Doyu <hdoyu@xxxxxxxxxx> wrote:
> > Support read-only mapping via struct dma_attrs.
> >
> > Signed-off-by: Hiroshi Doyu <hdoyu@xxxxxxxxxx>
> > ---
> > drivers/iommu/tegra-smmu.c | 41 +++++++++++++++++++++++++++++------------
> > 1 file changed, 29 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
> > index fab1f19..3aff4cd 100644
> > --- a/drivers/iommu/tegra-smmu.c
> > +++ b/drivers/iommu/tegra-smmu.c
> > @@ -862,12 +862,13 @@ static size_t __smmu_iommu_unmap_largepage(struct smmu_as *as, dma_addr_t iova)
> > }
> >
> > static int __smmu_iommu_map_pfn(struct smmu_as *as, dma_addr_t iova,
> > - unsigned long pfn)
> > + unsigned long pfn, int prot)
> Can you find 'prot' is used at other arch? In previous patch, you cast
{amd,intel}_iommu_map() take the IOMMU standard flags below and
translate it into each H/W dependent bits.
#define IOMMU_READ (1)
#define IOMMU_WRITE (2)
#define IOMMU_CACHE (4) /* DMA cache coherency */
The others like OMAP/MSM pass their H/W dependent bits all the way. I
think that they don't use IOMMU via DMA mapping API.
> it as 'int' but below code cast it as 'struct dma_attr' again.
> doesn't it better to use 'struct dma_attr' as parameter to avoid
> double cast? Of course you have to modify existing APIs to use 'struct
> dma_attr'.
If DMA mapping API is considered as the standard frontend of
IOMMU(API), that may be an option.
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