Re: [PATCH v6 2/2] arm64: dts: sdm845: Add gpu and gmu device nodes

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On 12/21/2018 2:59 AM, Stephen Boyd wrote:
Quoting Rob Herring (2018-12-19 15:47:25)
On Wed, Dec 19, 2018 at 4:40 PM Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
On Wed, Dec 19, 2018 at 12:40 PM Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
On Wed, Dec 19, 2018 at 12:09 PM Rob Herring <robh@xxxxxxxxxx> wrote:
...but it does have a frequency, doesn't it?

+   compatible = "operating-points-v2-qcom-level";
+
+   opp-710000000 {
+     opp-hz = /bits/ 64 <710000000>;
+     qcom,level = <RPMH_REGULATOR_LEVEL_TURBO_L1>;
+   };

Ah, I perhaps see the confusion.  So Rajendra's usage of
"operating-points-v2-qcom-level" [1] doesn't have a frequency but
Jordan's do.  So I guess it makes sense that Jordan's have the
fallback compatible but Rajendra's don't?

Is having it useful to s/w that doesn't understand
"operating-points-v2-qcom-level"? If so, then add
"operating-points-v2". If not, then don't.

The only benefit I see in having "operating-points-v2" is that we don't
need to update the of_skipped_node_table[] in drivers/platform/of.c to
have all the variants of operating-points-v2-* when they decide to not
use anything from the "base" binding.

If that fails to work because opp-hz is required for the
"operating-points-v2" binding but sometimes
operating-points-v2-qcom-level doesn't require it I guess we need to
update the skip table or make some generic property like
'this-is-not-a-device' that these various data tables in DT can be
marked with so we don't make platform devices for them.

Regardless of the above, we should update the binding for
operating-points-v2-qcom-level to say that opp-hz isn't always required
when the qcom-level compatible is present. It looks like it just says
that it builds on top of the opp binding so that's not obvious.

Sure, I can respin with those details added in.
So I am guessing the conclusion is to use a fallback "operating-points-v2"
compatible *only* when we do have opp-hz along with qcom,level (as in the
case with gpu) and not have a fallback compatible in cases when we don't
have opp-hz (as in the case of rpm power domains)?
That seems a little inconsistent, and given Rob said either way is fine,
just do one way or the other and not both, I am inclined to think we should
just have a "operating-points-v2-qcom-level" and no fallback compatible.
Does that make sense?

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