On Wed, Nov 5, 2014 at 4:42 PM, Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> wrote: > On Wed, Nov 05, 2014 at 10:15:36AM +0000, Chander Kashyap wrote: >> Exynos7 has core power down state where cores can be powered off independently. >> This patch adds support for this state. >> >> Entry latency for the core power down is calculated as follows: >> 1. Time difference is measured between cpuidle entry and exit. >> 2. WFI is skipped measuring the time. >> 3. The time is averaged out for 100000 cpuidle transactions with varying load. > - entry-latency-us > Usage: Required > "Definition: u32 value representing worst case latency in microseconds > required to enter the idle state. ..." > > Is that an average value in your opinion ? I am being pedantic, I know, > but we define bindings to be followed, not interpreted. Sorry i missed the point. The worst case value in a test set of 100000 cpuidle transactions is ~34us I will update this and resend the patch. > > Thanks, > Lorenzo > >> Exit latency and target residency are supplied as per HW team >> >> Signed-off-by: Chander Kashyap <k.chander@xxxxxxxxxxx> >> --- >> This patch has following dependencies: >> - [PATCH v5 0/8] arch: arm64: Enable support for Samsung Exynos7 SoC >> http://www.spinics.net/lists/linux-samsung-soc/msg37047.html >> Changes in v2: >> - Moved the cpu-idle-state property after reg property >> - removed the status property. >> >> Changes in v3: >> - Added the Entry latency calculation in commit message. >> >> arch/arm64/boot/dts/exynos/exynos7.dtsi | 17 +++++++++++++++++ >> 1 file changed, 17 insertions(+) >> >> diff --git a/arch/arm64/boot/dts/exynos/exynos7.dtsi b/arch/arm64/boot/dts/exynos/exynos7.dtsi >> index 50ae936..444dde1 100644 >> --- a/arch/arm64/boot/dts/exynos/exynos7.dtsi >> +++ b/arch/arm64/boot/dts/exynos/exynos7.dtsi >> @@ -37,6 +37,7 @@ >> compatible = "arm,cortex-a57", "arm,armv8"; >> enable-method = "psci"; >> reg = <0x0>; >> + cpu-idle-states = <&CPU_SLEEP>; >> }; >> >> cpu@1 { >> @@ -44,6 +45,7 @@ >> compatible = "arm,cortex-a57", "arm,armv8"; >> enable-method = "psci"; >> reg = <0x1>; >> + cpu-idle-states = <&CPU_SLEEP>; >> }; >> >> cpu@2 { >> @@ -51,6 +53,7 @@ >> compatible = "arm,cortex-a57", "arm,armv8"; >> enable-method = "psci"; >> reg = <0x2>; >> + cpu-idle-states = <&CPU_SLEEP>; >> }; >> >> cpu@3 { >> @@ -58,6 +61,20 @@ >> compatible = "arm,cortex-a57", "arm,armv8"; >> enable-method = "psci"; >> reg = <0x3>; >> + cpu-idle-states = <&CPU_SLEEP>; >> + }; >> + >> + idle-states { >> + entry-method = "arm,psci"; >> + >> + CPU_SLEEP: cpu-sleep { >> + compatible = "arm,idle-state"; >> + local-timer-stop; >> + arm,psci-suspend-param = <0x0010000>; >> + entry-latency-us = <20>; >> + exit-latency-us = <150>; >> + min-residency-us = <2100>; >> + }; >> }; >> }; >> >> -- >> 1.7.9.5 >> >> > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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