linux-kernel - [PATCH v1 0/3] Add required-opps support to devfreq passive gov

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Message-Id: <20190622003449.33707-1-saravanak@google.com>
Date:   Fri, 21 Jun 2019 17:34:45 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Saravana Kannan <saravanak@...gle.com>, kernel-team@...roid.com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1 0/3] Add required-opps support to devfreq passive gov

The devfreq passive governor scales the frequency of a "child" device
based on the current frequency of a "parent" device (not parent/child in
the sense of device hierarchy). As of today, the passive governor
requires one of the following to work correctly:
1. The parent and child device have the same number of frequencies
2. The child device driver passes a mapping function to translate from
   parent frequency to child frequency.

When (1) is not true, (2) is the only option right now. But often times,
all that is required is a simple mapping from parent's frequency to
child's frequency.

Since OPPs already support pointing to other "required-opps", add
support for using that to map from parent device frequency to child
device frequency. That way, every child device driver doesn't have to
implement a separate mapping function anytime (1) isn't true.

-Saravana

Saravana Kannan (3):
  OPP: Allow required-opps even if the device doesn't have power-domains
  OPP: Add function to look up required OPP's for a given OPP
  PM / devfreq: Add required OPPs support to passive governor

 drivers/devfreq/governor_passive.c | 25 +++++++++++--
 drivers/opp/core.c                 | 56 +++++++++++++++++++++++++++++-
 drivers/opp/of.c                   | 14 --------
 include/linux/pm_opp.h             | 11 ++++++
 4 files changed, 89 insertions(+), 17 deletions(-)

-- 
2.22.0.410.gd8fdbe21b5-goog