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

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Mark Rutland <mark.rutland@xxxxxxx> wrote @ Thu, 31 Oct 2013 18:31:33 +0100:

> > 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)
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