[PATCH 0/2] PM / Domains / OPP: Introduce domain-performance-state binding

From: Viresh Kumar
Date: Fri Nov 18 2016 - 04:23:40 EST


Some platforms have the capability to configure the performance state of
their Power Domains. The performance levels are represented by positive
integer values, a lower value represents lower performance state.

We had some discussions about it in the past on the PM list [1], which
is followed by discussions during the LPC. The outcome of all that was
that we should extend Power Domain framework to support active state
power management as well.

The power-domains until now were only concentrating on the idle state
management of the device and this needs to change in order to reuse the
infrastructure of power domains for active state management.

To get a complete picture of the proposed plan, following is what we
need to do:
- Create DT bindings to get domain performance state information for the
- Enhance OPP framework to parse these and call into the PM Qos
framework with a performance state request.
- Enhance PM Qos framework to provide the API to be used by consumers
(or OPP framework) and pass it on to the (Generic) Power Domain
- Enhance Generic Power Domain framework to accept such requests,
accumulate all belonging to a single power domain and call domain
driver specific callback with the performance state we want for the
- The domain driver shall then, in a platform specific way, set the
requested performance level.
- Note that these features are applicable to the CPU, GPU and other IIO
or non-IIO devices.
- There can be cases where a device can choose between multiple power
domains based on what performance level we want for the device. In
such cases, we should represent the multiplexer with a separate power
domain. In effect, the device (or OPP table) will correspond to a
single power domain, but the backend driver of that domain shall
implement the multiplexing functionality.

This patchset implements the very first part of this chain and
introduces a new optional property for the consumers of the
power-domains: domain-performance-state. This property can be used
directly by the consumer or its OPP table.


[1] https://marc.info/?l=linux-pm&m=147747923708075&w=2

Viresh Kumar (2):
PM / Domains: Introduce domain-performance-state binding
PM / OPP: Introduce domain-performance-state binding to OPP nodes

Documentation/devicetree/bindings/opp/opp.txt | 57 ++++++++++++++++++++++
.../devicetree/bindings/power/power_domain.txt | 6 +++
2 files changed, 63 insertions(+)