linux-kernel - Re: [PATCHv1 4/8] arm64: dts: qcom: msm8916: Use more generic idle state names

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Date:   Tue, 14 May 2019 18:12:20 +0200
From:   Niklas Cassel <niklas.cassel@...aro.org>
To:     Amit Kucheria <amit.kucheria@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        bjorn.andersson@...aro.org, andy.gross@...aro.org,
        David Brown <david.brown@...aro.org>,
        Li Yang <leoyang.li@....com>, Shawn Guo <shawnguo@...nel.org>,
        devicetree@...r.kernel.org
Subject: Re: [PATCHv1 4/8] arm64: dts: qcom: msm8916: Use more generic idle
 state names

On Fri, May 10, 2019 at 04:59:42PM +0530, Amit Kucheria wrote:
> Instead of using Qualcomm-specific terminology, use generic node names
> for the idle states that are easier to understand. Move the description
> into the "idle-state-name" property.
> 
> Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
> ---
>  arch/arm64/boot/dts/qcom/msm8916.dtsi | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/msm8916.dtsi b/arch/arm64/boot/dts/qcom/msm8916.dtsi
> index ded1052e5693..400b609bb3fd 100644
> --- a/arch/arm64/boot/dts/qcom/msm8916.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8916.dtsi
> @@ -110,7 +110,7 @@
>  			reg = <0x0>;
>  			next-level-cache = <&L2_0>;
>  			enable-method = "psci";
> -			cpu-idle-states = <&CPU_SPC>;
> +			cpu-idle-states = <&CPU_SLEEP_0>;
>  			clocks = <&apcs>;
>  			operating-points-v2 = <&cpu_opp_table>;
>  			#cooling-cells = <2>;
> @@ -122,7 +122,7 @@
>  			reg = <0x1>;
>  			next-level-cache = <&L2_0>;
>  			enable-method = "psci";
> -			cpu-idle-states = <&CPU_SPC>;
> +			cpu-idle-states = <&CPU_SLEEP_0>;
>  			clocks = <&apcs>;
>  			operating-points-v2 = <&cpu_opp_table>;
>  			#cooling-cells = <2>;
> @@ -134,7 +134,7 @@
>  			reg = <0x2>;
>  			next-level-cache = <&L2_0>;
>  			enable-method = "psci";
> -			cpu-idle-states = <&CPU_SPC>;
> +			cpu-idle-states = <&CPU_SLEEP_0>;
>  			clocks = <&apcs>;
>  			operating-points-v2 = <&cpu_opp_table>;
>  			#cooling-cells = <2>;
> @@ -146,7 +146,7 @@
>  			reg = <0x3>;
>  			next-level-cache = <&L2_0>;
>  			enable-method = "psci";
> -			cpu-idle-states = <&CPU_SPC>;
> +			cpu-idle-states = <&CPU_SLEEP_0>;
>  			clocks = <&apcs>;
>  			operating-points-v2 = <&cpu_opp_table>;
>  			#cooling-cells = <2>;
> @@ -160,8 +160,9 @@
>  		idle-states {
>  			entry-method="psci";

Please add a space before and after "=".

>  
> -			CPU_SPC: spc {
> +			CPU_SLEEP_0: cpu-sleep-0 {

While I like your idea of using power state names from
Server Base System Architecture document (SBSA) where applicable,
does each qcom power state have a matching state in SBSA?

These are the qcom power states:
https://source.codeaurora.org/quic/la/kernel/msm-4.4/tree/Documentation/devicetree/bindings/arm/msm/lpm-levels.txt?h=msm-4.4#n53

Note that qcom defines:
"wfi", "retention", "gdhs", "pc", "fpc"
while SBSA simply defines "idle_standby" (aka wfi), "idle_retention", "sleep".

Unless you know the equivalent name for each qcom power state
(perhaps several qcom power states are really the same SBSA state?),
I think that you should omit the renaming from this patch series.

>  				compatible = "arm,idle-state";
> +				idle-state-name = "standalone-power-collapse";
>  				arm,psci-suspend-param = <0x40000002>;
>  				entry-latency-us = <130>;
>  				exit-latency-us = <150>;
> -- 
> 2.17.1
>