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Subject: Re: [EXT] Re: [PATCH v5] arm64: dts: ls1088a: add one more thermal
 zone node
To:     Andy Tang <andy.tang@nxp.com>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>
Cc:     Leo Li <leoyang.li@nxp.com>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "mark.rutland@arm.com" <mark.rutland@arm.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
        "rui.zhang@intel.com" <rui.zhang@intel.com>,
        "edubezval@gmail.com" <edubezval@gmail.com>
References: <20190411083236.9377-1-andy.tang@nxp.com>
 <915c86d8-d00e-f1e1-e7f5-24bc225c8e42@linaro.org>
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From:   Daniel Lezcano <daniel.lezcano@linaro.org>
Message-ID: <6be740a0-aaa7-6b49-ba82-8d04d47b2339@linaro.org>
Date:   Fri, 12 Apr 2019 14:19:02 +0200
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On 12/04/2019 09:47, Andy Tang wrote:
> 
>> -----Original Message-----
>> From: Daniel Lezcano <daniel.lezcano@linaro.org>
>> Sent: 2019年4月12日 3:15
>> To: Andy Tang <andy.tang@nxp.com>; shawnguo@kernel.org
>> Cc: Leo Li <leoyang.li@nxp.com>; robh+dt@kernel.org; mark.rutland@arm.com;
>> linux-arm-kernel@lists.infradead.org; devicetree@vger.kernel.org;
>> linux-kernel@vger.kernel.org; linux-pm@vger.kernel.org; rui.zhang@intel.com;
>> edubezval@gmail.com
>> Subject: [EXT] Re: [PATCH v5] arm64: dts: ls1088a: add one more thermal zone
>> node
>>
>> WARNING: This email was created outside of NXP. DO NOT CLICK links or
>> attachments unless you recognize the sender and know the content is safe.
>>
>>
>>
>> On 11/04/2019 10:32, Yuantian Tang wrote:
>>> Ls1088a has 2 thermal sensors, core cluster and SoC platform. Core
>>> cluster sensor is used to monitor the temperature of core and SoC
>>> platform is for platform. The current dts only support the first sensor.
>>> This patch adds the second sensor node to dts to enable it.
>>>
>>> Signed-off-by: Yuantian Tang <andy.tang@nxp.com>
>>> ---
>>> v5:
>>>       - update the thermal zone name due to the length limitation
>>>       - remove cooling map in platform zone
>>> v4:
>>>       - use hyphen instead of underscore in node name
>>> v3:
>>>       - use more descriptive name for each zone
>>> v2:
>>>       - Add more information about sensors to description
>>>  arch/arm64/boot/dts/freescale/fsl-ls1088a.dtsi |   28
>> ++++++++++++++++++++---
>>>  1 files changed, 24 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/arm64/boot/dts/freescale/fsl-ls1088a.dtsi
>>> b/arch/arm64/boot/dts/freescale/fsl-ls1088a.dtsi
>>> index de93b42..de39672 100644
>>> --- a/arch/arm64/boot/dts/freescale/fsl-ls1088a.dtsi
>>> +++ b/arch/arm64/boot/dts/freescale/fsl-ls1088a.dtsi
>>> @@ -129,19 +129,19 @@
>>>       };
>>>
>>>       thermal-zones {
>>> -             cpu_thermal: cpu-thermal {
>>> +             core-cluster {
>>>                       polling-delay-passive = <1000>;
>>>                       polling-delay = <5000>;
>>>                       thermal-sensors = <&tmu 0>;
>>>
>>>                       trips {
>>> -                             cpu_alert: cpu-alert {
>>> +                             core_cluster_alert: core-cluster-alert {
>>>                                       temperature = <85000>;
>>>                                       hysteresis = <2000>;
>>>                                       type = "passive";
>>>                               };
>>>
>>> -                             cpu_crit: cpu-crit {
>>> +                             core_cluster_crit: core-cluster-crit {
>>>                                       temperature = <95000>;
>>>                                       hysteresis = <2000>;
>>>                                       type = "critical"; @@ -150,7
>>> +150,7 @@
>>>
>>>                       cooling-maps {
>>>                               map0 {
>>> -                                     trip = <&cpu_alert>;
>>> +                                     trip = <&core_cluster_alert>;
>>>                                       cooling-device =
>>>                                               <&cpu0
>> THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
>>>                                               <&cpu1
>> THERMAL_NO_LIMIT
>>> THERMAL_NO_LIMIT>, @@ -163,6 +163,26 @@
>>>                               };
>>>                       };
>>>               };
>>> +
>>> +             platform {
>>> +                     polling-delay-passive = <1000>;
>>> +                     polling-delay = <5000>;
>>> +                     thermal-sensors = <&tmu 1>;
>>> +
>>> +                     trips {
>>> +                             platform-alert {
>>> +                                     temperature = <85000>;
>>> +                                     hysteresis = <2000>;
>>> +                                     type = "passive";
>>> +                             };
>>> +
>>> +                             platform-crit {
>>> +                                     temperature = <95000>;
>>> +                                     hysteresis = <2000>;
>>> +                                     type = "critical";
>>> +                             };
>>> +                     };
>>> +             };
>>
>>
>> Unfortunately, the documentation says the thermal zone node must contain a
>> "cooling-maps" entry.
> That's a question.
> If I add "cooling-maps", then multiple zones will use same cooling device.
> If I don't, documentation says it is a " Required properties".
> I am wondering how it was dealt with on other platform supporting multiple zones.

I think the problem comes from the fact there are no governors capable
of handling multiple thermal zones.

The additional cooling device is the devfreq but as the mali driver is
not upstream, the cooling map for this device does not appear. We can
find the definitions and the driver in the AOSP [1].

Moreover, the power is usually managed by the IPA governor, but this one
can not handle multiple thermal zones, so the cooling devices are joined
together into a single thermal zone with their contribution to the
cooling effect.

Other definitions I have seen upstream are incomplete or broken.

[1]
https://android.googlesource.com/kernel/hikey-linaro/+/refs/heads/android-hikey-linaro-4.14/arch/arm64/boot/dts/hisilicon/hi3660.dtsi#1340

> Hi Shawn,
> What's your opinions about this?


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