* [PATCH v3] arm64: dts: exynos7: add support for cpuidle core power down
@ 2014-11-05 10:15 Chander Kashyap
2014-11-05 11:12 ` Lorenzo Pieralisi
0 siblings, 1 reply; 3+ messages in thread
From: Chander Kashyap @ 2014-11-05 10:15 UTC (permalink / raw)
To: linux-arm-kernel
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.
Exit latency and target residency are supplied as per HW team
Signed-off-by: Chander Kashyap <k.chander@samsung.com>
---
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 at 1 {
@@ -44,6 +45,7 @@
compatible = "arm,cortex-a57", "arm,armv8";
enable-method = "psci";
reg = <0x1>;
+ cpu-idle-states = <&CPU_SLEEP>;
};
cpu at 2 {
@@ -51,6 +53,7 @@
compatible = "arm,cortex-a57", "arm,armv8";
enable-method = "psci";
reg = <0x2>;
+ cpu-idle-states = <&CPU_SLEEP>;
};
cpu at 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
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH v3] arm64: dts: exynos7: add support for cpuidle core power down
2014-11-05 10:15 [PATCH v3] arm64: dts: exynos7: add support for cpuidle core power down Chander Kashyap
@ 2014-11-05 11:12 ` Lorenzo Pieralisi
2014-11-05 13:07 ` Chander Kashyap
0 siblings, 1 reply; 3+ messages in thread
From: Lorenzo Pieralisi @ 2014-11-05 11:12 UTC (permalink / raw)
To: linux-arm-kernel
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.
Thanks,
Lorenzo
> Exit latency and target residency are supplied as per HW team
>
> Signed-off-by: Chander Kashyap <k.chander@samsung.com>
> ---
> 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 at 1 {
> @@ -44,6 +45,7 @@
> compatible = "arm,cortex-a57", "arm,armv8";
> enable-method = "psci";
> reg = <0x1>;
> + cpu-idle-states = <&CPU_SLEEP>;
> };
>
> cpu at 2 {
> @@ -51,6 +53,7 @@
> compatible = "arm,cortex-a57", "arm,armv8";
> enable-method = "psci";
> reg = <0x2>;
> + cpu-idle-states = <&CPU_SLEEP>;
> };
>
> cpu at 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
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH v3] arm64: dts: exynos7: add support for cpuidle core power down
2014-11-05 11:12 ` Lorenzo Pieralisi
@ 2014-11-05 13:07 ` Chander Kashyap
0 siblings, 0 replies; 3+ messages in thread
From: Chander Kashyap @ 2014-11-05 13:07 UTC (permalink / raw)
To: linux-arm-kernel
On Wed, Nov 5, 2014 at 4:42 PM, Lorenzo Pieralisi
<lorenzo.pieralisi@arm.com> 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@samsung.com>
>> ---
>> 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 at 1 {
>> @@ -44,6 +45,7 @@
>> compatible = "arm,cortex-a57", "arm,armv8";
>> enable-method = "psci";
>> reg = <0x1>;
>> + cpu-idle-states = <&CPU_SLEEP>;
>> };
>>
>> cpu at 2 {
>> @@ -51,6 +53,7 @@
>> compatible = "arm,cortex-a57", "arm,armv8";
>> enable-method = "psci";
>> reg = <0x2>;
>> + cpu-idle-states = <&CPU_SLEEP>;
>> };
>>
>> cpu at 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 at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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2014-11-05 10:15 [PATCH v3] arm64: dts: exynos7: add support for cpuidle core power down Chander Kashyap
2014-11-05 11:12 ` Lorenzo Pieralisi
2014-11-05 13:07 ` Chander Kashyap
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