Re: [PATCH v5 02/13] dt-bindings: remoteproc: qcom: pas: Add QMP property

Sibi Sankar
2021-08-20T14:24:36Z

On 2021-08-20 00:25, Stephen Boyd wrote:
> Quoting Sibi Sankar (2021-08-18 20:02:05)
>> The load state power-domain, used by the co-processors to notify the
>> Always on Subsystem (AOSS) that a particular co-processor is up/down,
>> suffers from the side-effect of changing states during suspend/resume.
>> However the co-processors enter low-power modes independent to that of
>> the application processor and their states are expected to remain
>> unaltered across system suspend/resume cycles. To achieve this
>> behavior
>> let's drop the load state power-domain and replace them with the qmp
>> property for all SoCs supporting low power mode signalling.
>>
>
> How do we drop the load state property without breaking existing DTBs?
> Maybe we need to leave it there and then somehow make it optional? Or
> do
> we not care about this problem as the driver will start ignoring it?

We can afford to break the bindings
because of the following reason:

* Load state in mainline is currently
broken i.e. it doesn't serve its
main purpose of signalling AOP of
the correct state of Q6 during
system suspend/resume. Thus we
can maintain current functionality
even without the load state votes
i.e. when a new kernel with load
state removed is used with an older
dtb the remoteproc functionality
will remain the same.

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