On Mon, Sep 15, 2014 at 12:57:38PM +0100, Marek Szyprowski wrote:
> Hello,
Hi Marek,
Thanks for looking again at this -- I'll take at look at your exynos series
when I'm back in the UK next week.
> On 2014-09-12 18:34, Will Deacon wrote:
> > This patch adds a new function to the iommu_ops structure to allow an
> > OF device to be added to a specific IOMMU instance using the recently
> > merged generic devicetree binding for IOMMUs. The callback (of_xlate)
> > takes a struct device representing the master and an of_phandle_args
> > representing the IOMMU and the correspondong IDs for the new master.
> >
> > Signed-off-by: Will Deacon <will.dea...@arm.com>
> > ---
> > include/linux/iommu.h | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > index 4256f3ce1673..821eb0bd9f6c 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -21,6 +21,7 @@
> >
> > #include <linux/errno.h>
> > #include <linux/err.h>
> > +#include <linux/of.h>
> > #include <linux/types.h>
> > #include <trace/events/iommu.h>
> >
> > @@ -140,6 +141,10 @@ struct iommu_ops {
> > /* Get the numer of window per domain */
> > u32 (*domain_get_windows)(struct iommu_domain *domain);
> >
> > +#ifdef CONFIG_OF_IOMMU
> > + int (*of_xlate)(struct device *dev, struct of_phandle_args *args);
> > +#endif
>
>
> If I understand correctly, this callback is intended to do per-master
> initialization
> of the iommu structures required by the given iommu driver (I stored them in
> dev->archdata.iommu). However I really don't get what is the meaning of
> the return
> value. Is it a boolean value? It is used only by of_iommu_configure to
> check if
> the parse loop should be terminated...
It should probably return 0 on success, < 0 otherwise. I'll fix
of_iommu_configure to check for < 0 and only exit the loop then. The idea is
that we don't swizzle the DMA ops for a device to IOMMU ops if of_xlate
failed for any of its IDs.
Will
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