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

From: Lorenzo Pieralisi
Date: Wed Oct 15 2014 - 05:00:23 EST


On Wed, Oct 15, 2014 at 07:35:20AM +0100, Chander Kashyap wrote:
> Exynos7 has core power down state where cores can be powered off independently.
> This patch adds support for this state.

Please tell us more about the idle-state values you are adding, in particular
entry, exit latencies and min-residency values.

> 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
> - [PATCH v9 0/8] ARM generic idle states
> http://permalink.gmane.org/gmane.linux.power-management.general/49224

Series above was merged, so dependency is stale.

> arch/arm64/boot/dts/exynos/exynos7.dtsi | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/exynos/exynos7.dtsi b/arch/arm64/boot/dts/exynos/exynos7.dtsi
> index ce221ac..8e0a034 100644
> --- a/arch/arm64/boot/dts/exynos/exynos7.dtsi
> +++ b/arch/arm64/boot/dts/exynos/exynos7.dtsi
> @@ -36,6 +36,7 @@
> device_type = "cpu";
> compatible = "arm,cortex-a57", "arm,armv8";
> enable-method = "psci";
> + cpu-idle-states = <&CPU_SLEEP>;

I would add cpu-idle-states phandle after the reg property, as defined
in the idle states bindings.

> reg = <0x0>;
> };
>
> @@ -43,6 +44,7 @@
> device_type = "cpu";
> compatible = "arm,cortex-a57", "arm,armv8";
> enable-method = "psci";
> + cpu-idle-states = <&CPU_SLEEP>;
> reg = <0x1>;
> };
>
> @@ -50,6 +52,7 @@
> device_type = "cpu";
> compatible = "arm,cortex-a57", "arm,armv8";
> enable-method = "psci";
> + cpu-idle-states = <&CPU_SLEEP>;
> reg = <0x2>;
> };
>
> @@ -57,8 +60,23 @@
> device_type = "cpu";
> compatible = "arm,cortex-a57", "arm,armv8";
> enable-method = "psci";
> + cpu-idle-states = <&CPU_SLEEP>;
> reg = <0x3>;
> };
> +
> + 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>;
> + status = "enabled";

status ? This is not a documented property. If you need it please explain
why, define its bindings and we can see how to accommodate it.

Thank you,
Lorenzo

> + };
> + };
> };
>
> psci {
> --
> 1.7.9.5
>
>

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