Re: [PATCHv3 10/19] iommu/tegra: smmu: Get "nvidia,swgroups" from DT

Mark Rutland [off-list ref] wrote @ Thu, 31 Oct 2013 18:31:33 +0100:

quoted

Assuming "swgroup" is "memory client ID", why can't the driver just
create a list/... of known swgroups at runtime, based on the swgroup
values that each device uses, which would presumably be either
hard-coded in the client device's driver, or represented in the DT smmu
property's "iommu specifier" value.

Assuming that the swgroup values of IP block instances are static, that sounds
like the ARM SMMU binding approach. Are the IDs static, or can they be assigned
at runtime?

It's static.

But swgroup ID isn't documented in TRM. ID is basically calculated from register offset.

<swgroup ID> = (MC_SMMU_<swgroup name>_ASID_0 - MC_SMMU_<the 1st swgroup name>_ASID_0) / 4

Or 

MC_SMMU_<swgroup name>_ASID_0 = 4 * <swgroup ID> + MC_SMMU_<the 1st swgroup name>_ASID_0)