linux-kernel - Re: [PATCH V5 5/5] arm64: dts: imx8mm: Enable cpu-idle driver

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Message-ID: <34c03d76-ae61-63b4-153f-3f9911cc962e@linaro.org>
Date:   Thu, 15 Aug 2019 18:12:50 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Anson.Huang@....com, catalin.marinas@....com, will@...nel.org,
        robh+dt@...nel.org, mark.rutland@....com, shawnguo@...nel.org,
        s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
        linux-imx@....com, tglx@...utronix.de, leonard.crestez@....com,
        aisheng.dong@....com, daniel.baluta@....com, ping.bai@....com,
        l.stach@...gutronix.de, abel.vesa@....com,
        andrew.smirnov@...il.com, ccaione@...libre.com, angus@...ea.ca,
        agx@...xcpu.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH V5 5/5] arm64: dts: imx8mm: Enable cpu-idle driver


Hi Anson,

sorry for the late review, I've been pretty busy.

If Shawn is ok, I can pick the patches 1-4 in my tree and then this one
after you fix the comments below.

On 10/07/2019 08:30, Anson.Huang@....com wrote:

[ ... ]

> +		idle-states {
> +			entry-method = "psci";
> +
> +			cpu_sleep_wait: cpu-sleep-wait {

Is that a retention state or a powerdown? It is preferable to change the
name to the idle state naming convention given in the PSCI documentation
[1] page 16-17


> +				compatible = "arm,idle-state";
> +				arm,psci-suspend-param = <0x0010033>;
> +				local-timer-stop;
> +				entry-latency-us = <1000>;
> +				exit-latency-us = <700>;
> +				min-residency-us = <2700>;
> +				wakeup-latency-us = <1500>;

It is pointless to specify the entry + exit *and* the wakeup-latency [2].

Thanks

  -- Daniel

[1]
http://infocenter.arm.com/help/topic/com.arm.doc.den0022d/Power_State_Coordination_Interface_PDD_v1_1_DEN0022D.pdf

[2]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/cpuidle/dt_idle_states.c#n41



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