From mboxrd@z Thu Jan 1 00:00:00 1970 From: Quentin Perret Subject: [PATCH 7/7] arm: dts: vexpress-v2p-ca15_a7: Add cpu dynamic-power-coefficient information Date: Mon, 28 Jan 2019 16:55:22 +0000 Message-ID: <20190128165522.31749-8-quentin.perret@arm.com> References: <20190128165522.31749-1-quentin.perret@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190128165522.31749-1-quentin.perret@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: rjw@rjwysocki.net, viresh.kumar@linaro.org, sudeep.holla@arm.com, liviu.dudau@arm.com, lorenzo.pieralisi@arm.com, robh+dt@kernel.org, mark.rutland@arm.com, nm@ti.com, sboyd@kernel.org Cc: linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, dietmar.eggemann@arm.com, mka@chromium.org, quentin.perret@arm.com List-Id: devicetree@vger.kernel.org From: Dietmar Eggemann A CPUfreq driver, like the ARM big.LITTLE driver used on the TC2 board, which provide the Energy Model with power cost information via the PM_OPP of_dev_pm_opp_get_cpu_power() function, do need the dynamic-power-coefficient (C) in the device tree. Method used to obtain the C value: C is computed by measuring energy (E) consumption of a frequency domain (FD) over a 10s runtime (t) sysbench workload running at each Operating Performance Point (OPP) affine to 1 or 2 CPUs of that FD while the other CPUs of the system are hotplugged out. By definition all CPUs of a FD have the the same micro-architecture. An OPP is characterized by a certain frequency (f) and voltage (V) value. The corresponding power values (P) are calculated by dividing the delta of the E values between the runs with 2 and 1 CPUs by t. With n data tuples (P, f, V), n equal to number of OPPs for this frequency domain, we can solve C by: P = Pstat + Pdyn P = Pstat + CV²f Cx = (Px - P1)/(Vx²fx - V1²f1) with x = {2, ..., n} The C value is the arithmetic mean out of {C2, ..., Cn}. Signed-off-by: Dietmar Eggemann Signed-off-by: Quentin Perret --- arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts b/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts index a2ccacd07f4f..00cd9f5bef2e 100644 --- a/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts +++ b/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts @@ -42,6 +42,7 @@ cci-control-port = <&cci_control1>; cpu-idle-states = <&CLUSTER_SLEEP_BIG>; capacity-dmips-mhz = <1024>; + dynamic-power-coefficient = <990>; }; cpu1: cpu@1 { @@ -51,6 +52,7 @@ cci-control-port = <&cci_control1>; cpu-idle-states = <&CLUSTER_SLEEP_BIG>; capacity-dmips-mhz = <1024>; + dynamic-power-coefficient = <990>; }; cpu2: cpu@2 { @@ -60,6 +62,7 @@ cci-control-port = <&cci_control2>; cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>; capacity-dmips-mhz = <516>; + dynamic-power-coefficient = <133>; }; cpu3: cpu@3 { @@ -69,6 +72,7 @@ cci-control-port = <&cci_control2>; cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>; capacity-dmips-mhz = <516>; + dynamic-power-coefficient = <133>; }; cpu4: cpu@4 { @@ -78,6 +82,7 @@ cci-control-port = <&cci_control2>; cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>; capacity-dmips-mhz = <516>; + dynamic-power-coefficient = <133>; }; idle-states { -- 2.20.1