linux-kernel - [PATCH v3 0/4] Clarify abstract scale usage for power values in Energy Model, EAS and IPA

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Message-Id: <20201019140601.3047-1-lukasz.luba@arm.com>
Date:   Mon, 19 Oct 2020 15:05:57 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-doc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     robh+dt@...nel.org, amitk@...nel.org, corbet@....net,
        daniel.lezcano@...aro.org, lukasz.luba@....com,
        Dietmar.Eggemann@....com, morten.rasmussen@....com,
        qperret@...gle.com, dianders@...omium.org, mka@...omium.org,
        rnayak@...eaurora.org, rafael@...nel.org, sudeep.holla@....com,
        viresh.kumar@...aro.org, sboyd@...nel.org, nm@...com
Subject: [PATCH v3 0/4] Clarify abstract scale usage for power values in Energy Model, EAS and IPA

Hi all,

The Energy Model supports power values expressed in an abstract scale.
This has an impact on Intelligent Power Allocation (IPA) and should be
documented properly. Kernel sub-systems like EAS, IPA and DTPM
(new comming PowerCap framework) would use the new flag to capture
potential miss-configuration where the devices have registered different
power scales, thus cannot operate together.

There was a discussion below v2 of this patch series, which might help
you to get context of these changes [2].

The agreed approach is to have the DT as a source of power values expressed
always in milli-Watts and the only way to submit with abstract scale values
is via the em_dev_register_perf_domain() API.

Changes:
v3:
- added boolean flag to struct em_perf_domain and registration function
  indicating if EM holds real power values in milli-Watts (suggested by
  Daniel and aggreed with Quentin)
- updated documentation regarding this new flag
- dropped DT binding change for 'sustainable-power'
- added more maintainers on CC (due to patch 1/4 touching different things)
v2 [2]:
- updated sustainable power section in IPA documentation
- updated DT binding for the 'sustainable-power'
v1 [1]:
- simple documenation update with new 'abstract scale' in EAS, EM, IPA

Regards,
Lukasz Luba

[1] https://lore.kernel.org/linux-doc/20200929121610.16060-1-lukasz.luba@arm.com/
[2] https://lore.kernel.org/lkml/20201002114426.31277-1-lukasz.luba@arm.com/

Lukasz Luba (4):
  PM / EM: Add a flag indicating units of power values in Energy Model
  docs: Clarify abstract scale usage for power values in Energy Model
  PM / EM: update the comments related to power scale
  docs: power: Update Energy Model with new flag indicating power scale

 .../driver-api/thermal/power_allocator.rst    | 13 +++++++-
 Documentation/power/energy-model.rst          | 30 +++++++++++++++----
 Documentation/scheduler/sched-energy.rst      |  5 ++++
 drivers/cpufreq/scmi-cpufreq.c                |  3 +-
 drivers/opp/of.c                              |  2 +-
 include/linux/energy_model.h                  | 20 ++++++++-----
 kernel/power/energy_model.c                   | 26 ++++++++++++++--
 7 files changed, 81 insertions(+), 18 deletions(-)

-- 
2.17.1