[PATCH v2 03/22] ARM: tegra: Create a DT header defining swgroups ID

[Hiroshi Doyu]

Stephen Warren <swarren at wwwdotorg.org> wrote @ Wed, 17 Jul 2013 01:07:12 +0200:

> On 07/05/2013 04:44 AM, Hiroshi Doyu wrote:
> > Create a header file to define the swgroup IDs used by the IOMMU(SMMU)
> > binding. "swgroup" is a group of H/W clients in Tegra SoC from S/W POV.
> > 
> > This will allow the same header to be used by both device tree files,
> > and drivers implementing this binding, which guarantees that the two
> > stay in sync. This also makes device trees more readable by using names
> > instead of magic numbers.
> 
> Why does the driver need these constants; shouldn't it simply support
> 0..n SW group IDs that all work the same way? Or, is there some reason
> for it to know the identities?
> 
> > diff --git a/include/dt-bindings/memory/tegra-swgroup.h b/include/dt-bindings/memory/tegra-swgroup.h
> 
> s/memory/iommu/?

This info would be used in PMC code as well, which H/W belongs to
which swgroup. So I use the term "memory(-client)" instead of "iommu".

> s/tegra-swgroup.h/tegra-smmu.h/?

Is "tegra-memory-clients.h" preferable, then?

> > +#define TEGRA_SWGROUP_AFI 0
> 
> Should this file document which values are valid for which SoCs? Should
> there be separate files for each SoC; I don't know if it's guaranteed
> that IDs won't be re-assigned between different SoCs.

I've checked all SoC which I can refer. Those IDs are calculated from
the register offset. But I haven't got any explicit guarantee from H/W
designers yet.

> > +#define TEGRA_SWGROUP_BIT(x)	(1ULL << TEGRA_SWGROUP_##x)
> > +
> > +#define TEGRA30_SWGROUP_ALL	<0x00000000 0x000779ff>
> > +#define TEGRA114_SWGROUP_ALL	<0x00000000 0x01b659fe>
> 
> Are those 3 values needed by DT files, or just the driver?

Only from DT.