On Thu, 24 Oct 2019 at 17:26, Sudeep Holla [off-list ref] wrote:

On Thu, Oct 10, 2019 at 01:39:26PM +0200, Ulf Hansson wrote:

quoted

Update PSCI DT bindings to allow to represent idle states for CPUs and the
CPU topology, by using a hierarchical layout. Primarily this is done by
re-using the existing power domain description [1] and the domain idle
state description [2].

Let's also take the opportunity to update the examples to clarify the
difference between the currently supported flattened layout vs the new
hierarchical layout.

This looks fine to me. FWIW:

Reviewed-by: Sudeep Holla <redacted>

But before this gets merged, I would like to add another but "the golden"
example Qcom *always* referred during ACPI LPI discussions. Ofcourse, it
can be addition patch and if I get time, I can write this but no promise
ATM.

I like the description below, thanks for clarifying that.

Although, as you say, we can for sure add it on top. As a matter of
fact, I think that is even the best way forward, as currently we can't
support it (because of limitations in genpd, that I have started
working on a bit).

Hierarchical Representation:
System
1. SYSTEM_RET
2. SYSTEM_PG

        Cluster#0
        1. CLUSTER_RET
        2. CLUSTER_PG

                Core#0
                1. CORE_CG
                2. CORE_RET
                3. CORE_PG

                Core#1
                1. CORE_CG
                2. CORE_RET
                3. CORE_PG
        Cluster#1 (ditto)

Flattened Representation:

Core#0
        1 CORE_CG
        2 CORE_RET
        3 CORE_RET + CLUSTER_RET
        4 CORE_RET + CLUSTER_RET + SYSTEM_RET
        5 CORE_PG
        6 CORE_PG  + CLUSTER_RET
        7 CORE_PG  + CLUSTER_RET + SYSTEM_RET
        8 CORE_PG  + CLUSTER_PG
        9 CORE_PG  + CLUSTER_PG  + SYSTEM_RET
       10 CORE_PG  + CLUSTER_PG  + SYSTEM_PG

Though we may not implement everything needed to support this, but
we must ensure we don't have to end up in a situation breaking backward
compatibility trying to support the same.

Yep, right. I don't see any issue in regards to backward compatibility
to support this above.

Thanks for reviewing!

Kind regards
Uffe