On Tue, Dec 20, 2016 at 09:29:21PM -0600, Rob Herring wrote: > On Fri, Dec 16, 2016 at 01:19:29PM +0000, Robin Murphy wrote: > > The current SMR masking support using a 2-cell iommu-specifier is > > primarily intended to handle individual masters with large and/or > > complex Stream ID assignments; it quickly gets a bit clunky in other SMR > > use-cases where we just want to consistently mask out the same part of > > every Stream ID (e.g. for MMU-500 configurations where the appended TBU > > number gets in the way unnecessarily). Let's add a new property to allow > > a single global mask value to better fit the latter situation. > > > > CC: Stuart Yoder <stuart.yoder@xxxxxxx> > > Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx> > > --- > > > > Compile-tested only... > > > > Documentation/devicetree/bindings/iommu/arm,smmu.txt | 8 ++++++++ > > drivers/iommu/arm-smmu.c | 4 +++- > > 2 files changed, 11 insertions(+), 1 deletion(-) > > > > diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt > > index e862d1485205..98f5cbe5fdb4 100644 > > --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt > > +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt > > @@ -60,6 +60,14 @@ conditions. > > aliases of secure registers have to be used during > > SMMU configuration. > > > > +- stream-match-mask : Specifies a fixed SMR mask value to combine with > > Needs a vendor prefix. Why does this need a vendor prefix? I'm not fussed either way, but since the stream-match-mask is an optional architectural concept and not specific to an implementation, it seems strange to me that it would need a prefix whereas something like #global-interrupts does not. > > + the Stream ID value from every iommu-specifier. This > > + may be used instead of an "#iommu-cells" value of 2 > > + when there is no need for per-master SMR masks, but > > + it is still desired to mask some portion of every > > + Stream ID (e.g. for certain MMU-500 configurations > > + given globally unique external IDs). Robin -- it might be worth a sentence here saying that the property is ignored if stream matching isn't supported by the hardware. Will -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
