linux-kernel - [PATCH V8 3/3] OPP: Allow "opp-hz" and "opp-microvolt" to contain magic values

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Date:   Mon, 18 Dec 2017 15:51:30 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     ulf.hansson@...aro.org, Kevin Hilman <khilman@...nel.org>,
        robh+dt@...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>,
        rnayak@...eaurora.org, sudeep.holla@....com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH V8 3/3] 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.

Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
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 4e4f30288c8b..00a3bdbd0f1f 100644
--- a/Documentation/devicetree/bindings/opp/opp.txt
+++ b/Documentation/devicetree/bindings/opp/opp.txt
@@ -167,6 +167,12 @@ properties.
   functioning of the current device at the current OPP (where this property is
   present).
 
+
+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.
 
 / {
-- 
2.15.0.194.g9af6a3dea062