linux-kernel - [PATCH v5 1/3] devicetree: bindings: Add optional dynamic-power-coefficient property

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Message-Id: <1447761983-12415-2-git-send-email-punit.agrawal@arm.com>
Date:	Tue, 17 Nov 2015 12:06:21 +0000
From:	Punit Agrawal <punit.agrawal@....com>
To:	linux-pm@...r.kernel.org
Cc:	Punit Agrawal <punit.agrawal@....com>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, edubezval@...il.com,
	dawei.chien@...iatek.com, javi.merino@....com,
	viresh.kumar@...aro.org, rjw@...ysocki.net,
	Mark Rutland <mark.rutland@....com>
Subject: [PATCH v5 1/3] devicetree: bindings: Add optional dynamic-power-coefficient property

The dynamic power consumption of a device is proportional to the
square of voltage (V) and the clock frequency (f). It can be expressed as

Pdyn = dynamic-power-coefficient * V^2 * f.

The coefficient represents the running time dynamic power consumption in
units of mw/MHz/uVolt^2 and can be used in the above formula to
calculate the dynamic power in mW.

Signed-off-by: Punit Agrawal <punit.agrawal@....com>
Acked-by: Rob Herring <robh@...nel.org>
Reviewed-by: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Mark Rutland <mark.rutland@....com>
---
 Documentation/devicetree/bindings/arm/cpus.txt | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt
index 3a07a87..6aca64f 100644
--- a/Documentation/devicetree/bindings/arm/cpus.txt
+++ b/Documentation/devicetree/bindings/arm/cpus.txt
@@ -242,6 +242,23 @@ nodes to be present and contain the properties described below.
 		Definition: Specifies the syscon node controlling the cpu core
 			    power domains.
 
+	- dynamic-power-coefficient
+		Usage: optional
+		Value type: <prop-encoded-array>
+		Definition: A u32 value that represents the running time dynamic
+			    power coefficient in units of mW/MHz/uVolt^2. The
+			    coefficient can either be calculated from power
+			    measurements or derived by analysis.
+
+			    The dynamic power consumption of the CPU  is
+			    proportional to the square of the Voltage (V) and
+			    the clock frequency (f). The coefficient is used to
+			    calculate the dynamic power as below -
+
+			    Pdyn = dynamic-power-coefficient * V^2 * f
+
+			    where voltage is in uV, frequency is in MHz.
+
 Example 1 (dual-cluster big.LITTLE system 32-bit):
 
 	cpus {
-- 
2.6.2

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