On Fri, Aug 12 2016 at 04:08 -0600, Sudeep Holla wrote:

On 11/08/16 22:10, Lina Iyer wrote:

quoted

On Wed, Aug 10 2016 at 12:09 -0600, Sudeep Holla wrote:

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[...]

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cluster0
   CLUSTER_RET(Retention)
   CLUSTER_PG(Power Gate)
   core0
       CORE_RET
       CORE_PG
   core1
       CORE_RET
       CORE_PG

cluster1
   CLUSTER_RET
   CLUSTER_PG
   core0
       CORE_RET
       CORE_PG
   core1
       CORE_RET
       CORE_PG

Platform Co-ordinate supports the following states and we should be
able to determine that from the binding:

CORE_RET
CORE_PG
CORE_RET + CLUSTER_RET

The problem that we have to sove here is knowing that CORE_RET +
CLUSTER_PG (hypothetically) an invalid combination. Kevin and
I debated it in the earlier RFC and we dont have a good way to solve
this generically for all devices.

Yes, I agree it's complex. But that needs to be solved IMO.

I can think of 2 possible solutions:

1. Index the states(which people have not liked, but as along as we
  don't use it in the code as it for any other purpose, it should be
  fine) and then have each state mentioning what parent state can be
  entered at this child state(i.e. starting index and all states below
  it)

This is how QCOM solved it downstream.

2. Something similar to (1) but without index instead phandles.

The problem is when you have non-CPU devices in the device tree and
since they do not have a way to represent states like CPU, we did not
have a clear path to that. Hence we punted that to later. Whatever we
do, we should solve it for a generic PM domain, not just CPU domains.

Thanks,
Lina

Again these are just thoughts, others may think of some better
solution(s). Sorry I haven't followed all the previous threads in detail.

-- 
Regards,
Sudeep