On Thu, Oct 31, 2013 at 08:18:08AM +0000, Hiroshi Doyu wrote: > Stephen Warren <[email protected]> wrote @ Wed, 30 Oct 2013 23:44:04 > +0100: > > > > + host1x { > > > + compatible = "nvidia,tegra30-host1x", "simple-bus"; > > > + nvidia,memory-clients = <&smmu TEGRA_SWGROUP_HC>; > > > + .... > > > + gr3d { > > > + compatible = "nvidia,tegra30-gr3d"; > > > + nvidia,memory-clients = <&smmu TEGRA_SWGROUP_NV > > > + TEGRA_SWGROUP_NV2>; > > > > Why one cell for the host1x property, and two cells for the gr3d > > property; shouldn't they be the same length? > > That can vary. Even a single device node in DT can belong to multiple > software groups.
Same with ARM SMMU. > > > > diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c > > > > > +static u64 smmu_of_get_memory_client(struct device *dev) > > > > > + np = of_parse_phandle(dev->of_node, propname, 0); > > > + if (np != smmu_handle->dev->of_node) > > > + return ~0; > > > + > > > + prop = of_get_property(dev->of_node, propname, &bytes); > > > + if (!prop || !bytes) > > > + return ~0; > > > > of_parse_phandle_with_fixed_args() might be a good fit here, or perhaps > > require a property #smmu-cells in the SMMU node, thus allowing the > > non-fixed-length of_parse_phandle_with_args() to be used here. > > I once considered of_parse_phandle_with_args() but I couldn't use that > since "#smmu-cells" needed to be fixed in smmu node, not in client > node. In this case, the number of argument(number of swgroup IDs) > varies per client device. For the ARM SMMU binding, each device has a #stream-id-cells property describing how many IDs it has, and then the SMMU node has a phandle+args linkage to each of the devices attached to it, describing their stream IDs. While this does have some limitations (a device can't be plugged into multiple SMMUs with a different number of IDs), it seems generally sane. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
