On Tue, Nov 19, 2013 at 08:45:02PM +0000, Rob Herring wrote: > On 11/19/2013 11:35 AM, Will Deacon wrote: > > Adding Andreas and Rob for input on potential binding additions to the SMMU. > > The above proposal would be an incompatible change. However, I think we > could still deal with a change in this binding at this stage. > > One way approach to handle this without changing the binding would be to > scan the DT for all iommu's up front and create a list of all nodes and > their iommu parent. The fact that the hierarchy is described in a way > that doesn't fit Linux well is really a Linux implementation detail. > > If changing the binding, a simple approach would be to allow > 'smmu-parent' to be a bus and/or device property and not just for > chained iommu's. This could be a global or bus property that is > inherited. Like interrupt-parent, you would have to deal with the parent > being itself. Also, perhaps iommu-parent would be a better name. In any > case, I'd like to see this all be a generic iommu binding. I like that idea. I've recently been toying with removing the chained IOMMU support, since I don't think anybody is using it who is interested in mainline. However, making it more general sounds like a better idea. One potential issue is that I think the nvidia guys want to describe masters that master via multiple SMMUs (which I believe was the motivation for moving the stream-ids out into the master nodes, rather than keeping them in the SMMU). Again, that's not something we can easily add to the arm-smmu, because the incoming stream-ids are a property of the SMMU node. So the question is: do we actually need to describe masters that master through multiple SMMUs as a single node in the devicetree? Will -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
