2014-11-11 05:31:54

by Chander Kashyap

Subject: [PATCH v5] arm64: dts: exynos7: add support for cpuidle core power down

Exynos7 supports multiple idle states. Core power down is one such
idle state, where cores can be powered off independently.

This patch adds support for core power down idle state.

Entry latency for core power down idle state is calculated as follows:
1. Time difference is measured between cpuidle entry and exit.
2. WFI is skipped for measuring the time.
3. Select the worst case time in a set of 100000 cpuidle transactions,
with varying load.

Exit latency and min residency values are supplied as per HW team.

Signed-off-by: Chander Kashyap <[email protected]>
Acked-by: Lorenzo Pieralisi <[email protected]>
---
This patch has following dependencies:
- [PATCH v5 0/8] arch: arm64: Enable support for Samsung Exynos7 SoC
http://www.spinics.net/lists/arm-kernel/msg375961.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.
Changes in v4:
- Corrected the commit message.
- Corrected the entry latency value.
Changes in v5:
- Commit message modified

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 d7a37c3..891eef4 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";
reg = <0x0>;
enable-method = "psci";
+ cpu-idle-states = <&CPU_SLEEP>;
};

cpu@1 {
@@ -44,6 +45,7 @@
compatible = "arm,cortex-a57", "arm,armv8";
reg = <0x1>;
enable-method = "psci";
+ cpu-idle-states = <&CPU_SLEEP>;
};

cpu@2 {
@@ -51,6 +53,7 @@
compatible = "arm,cortex-a57", "arm,armv8";
reg = <0x2>;
enable-method = "psci";
+ cpu-idle-states = <&CPU_SLEEP>;
};

cpu@3 {
@@ -58,6 +61,20 @@
compatible = "arm,cortex-a57", "arm,armv8";
reg = <0x3>;
enable-method = "psci";
+ 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 = <34>;
+ exit-latency-us = <150>;
+ min-residency-us = <2100>;
+ };
};
};

--
1.9.1

2014-11-27 07:21:24

by Kukjin Kim

Subject: RE: [PATCH v5] arm64: dts: exynos7: add support for cpuidle core power down

Chander Kashyap wrote:
>
> Exynos7 supports multiple idle states. Core power down is one such
> idle state, where cores can be powered off independently.
>
> This patch adds support for core power down idle state.
>
> Entry latency for core power down idle state is calculated as follows:
> 1. Time difference is measured between cpuidle entry and exit.
> 2. WFI is skipped for measuring the time.
> 3. Select the worst case time in a set of 100000 cpuidle transactions,
> with varying load.
>
> Exit latency and min residency values are supplied as per HW team.
>
> Signed-off-by: Chander Kashyap <[email protected]>
> Acked-by: Lorenzo Pieralisi <[email protected]>

Lorenzo, thanks for your ack. Will apply.

- Kukjin

> ---
> This patch has following dependencies:
> - [PATCH v5 0/8] arch: arm64: Enable support for Samsung Exynos7 SoC
> http://www.spinics.net/lists/arm-kernel/msg375961.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.
> Changes in v4:
> - Corrected the commit message.
> - Corrected the entry latency value.
> Changes in v5:
> - Commit message modified
>
> 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 d7a37c3..891eef4 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";
> reg = <0x0>;
> enable-method = "psci";
> + cpu-idle-states = <&CPU_SLEEP>;
> };
>
> cpu@1 {
> @@ -44,6 +45,7 @@
> compatible = "arm,cortex-a57", "arm,armv8";
> reg = <0x1>;
> enable-method = "psci";
> + cpu-idle-states = <&CPU_SLEEP>;
> };
>
> cpu@2 {
> @@ -51,6 +53,7 @@
> compatible = "arm,cortex-a57", "arm,armv8";
> reg = <0x2>;
> enable-method = "psci";
> + cpu-idle-states = <&CPU_SLEEP>;
> };
>
> cpu@3 {
> @@ -58,6 +61,20 @@
> compatible = "arm,cortex-a57", "arm,armv8";
> reg = <0x3>;
> enable-method = "psci";
> + 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 = <34>;
> + exit-latency-us = <150>;
> + min-residency-us = <2100>;
> + };
> };
> };
>
> --
> 1.9.1