linux-kernel - [RFC V7 2/2] OPP: Allow "opp-hz" and "opp-microvolt" to contain magic values

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Message-Id: <23ba51eaa6b52117458165dccc00a95cf8e86e1d.1509453284.git.viresh.kumar@linaro.org>
Date:   Tue, 31 Oct 2017 18:17:03 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     ulf.hansson@...aro.org, Kevin Hilman <khilman@...nel.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...eaurora.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        robh+dt@...nel.org, rnayak@...eaurora.org, sudeep.holla@....com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC V7 2/2] OPP: Allow "opp-hz" and "opp-microvolt" to contain magic values

On some platforms the exact frequency or voltage may be hidden from the
OS by the firmware. Allow such configurations to pass magic values in
the "opp-hz" or the "opp-microvolt" properties, which should be
interpreted in a platform dependent way.

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 Documentation/devicetree/bindings/opp/opp.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
index 203e09fe7698..9c5056fb120f 100644
--- a/Documentation/devicetree/bindings/opp/opp.txt
+++ b/Documentation/devicetree/bindings/opp/opp.txt
@@ -166,6 +166,12 @@ properties.
   "power-domains" property. Also, either all or none of the OPP nodes in an OPP
   table should have it set.
 
+
+On some platforms the exact frequency or voltage may be hidden from the OS by
+the firmware and the "opp-hz" or the "opp-microvolt" properties may contain
+magic values that represent the frequency or voltage in a firmware dependent
+way, for example an index of an array in the firmware.
+
 Example 1: Single cluster Dual-core ARM cortex A9, switch DVFS states together.
 
 / {
-- 
2.15.0.rc1.236.g92ea95045093