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Date:   Sun, 25 Jun 2017 20:48:13 +0530
From:   Anand Moon <linux.amoon@...il.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Willy Wolff <willy.mh.wolff@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>,
        Kukjin Kim <kgene@...nel.org>,
        Javier Martinez Canillas <javier@....samsung.com>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: dts: exynos: Exynos5422 Odroid-XU* incomplete
 thermal-zones definition

Hi Krzystof,

On 25 June 2017 at 19:01, Krzysztof Kozlowski <krzk@...nel.org> wrote:
> On Sun, Jun 25, 2017 at 06:53:24PM +0530, Anand Moon wrote:
>> Hi Willy,
>>
>> On 24 June 2017 at 02:39, Willy Wolff <willy.mh.wolff@...il.com> wrote:
>> > Odroid XU*-familly boards has thermal sensors per A15 cores, but the actual
>> >  thermal-zones define only cooling-maps action for cpu0.
>> >
>> > If the application is running on all cores but core4 (first core of the A15
>> >  cluster), the CPU can reach high temperature without any proper cooling
>> >  action.
>> >
>> > As already discus in prior mail, and on IRC, it's a quit big code
>> > duplication, but I don't found the write way to express that in a better
>> >  way.
>> >
>> > The situation for this board is that we have multiple sensors, but
>> >  matching cooling devices for these sensors act for the same physical
>> >  device (FAN and A15 cluster, as each core of the cluster share the same
>> >  frequency).
>> > In fact, of-thermal.c:473:thermal_zone_of_sensor_register() can't use
>> > multiple sensors for one single thermal zone.
>> > This patch follow the path taken in arch/arm/boot/dts/qcom-apq8084.dtsi:97
>> >
>> > I'm interested to extending the thermal driver, but it will takes time.
>> >  So this is a workaround before refactoring the driver.
>> > If somebody knows how to write it better, any advice and suggestions
>> > are more than welcome.
>> >
>> > Also, the comment for cpu_alert4 in cooling-maps definition is not
>> > accurate, 11 steps for A15 correspond to 700MHz, not 600MHz.
>> >
>>
>> [snip]
>>
>> Few point to from my side.
>>
>> 1: We should also increase the trip points temperature so that it can
>> throttle at high temperature.
>
> It is not related to this problem. If you wish to address different
> problem related to non-optimal choice of temperature, then please send a
> separate patch explaining chosen values.

Certain task  tends to run slow in current thermal zone setting.
If needed I will send a patch for this.

>> 2: We should also increase the tips from 4 to 8 to support different
>> cluster of cpu's.
>
> There are 4 CPU thermal zones on Exynos5422. What do you want to expand?

What I meant was to support more trip point to address below.
[    2.776320] exynos-tmu 100a0000.tmu: More trip points than
supported by this TMU.
[    2.782370] exynos-tmu 100a0000.tmu: 2 trip points should be
configured in polling mode.

>> 3: To avoid duplication of cooling-maps we can make tmu sensor work
>> differently for cluster of cpu's
>>       tmu_cpu0: handle pwm-fan control.
>>       tmu_cpu1: handle cpu[0-3] cpufreq mapping.
>>       tmu_cpu2: handle cpu[4-7] cpufreq mapping.
>
> I miss the point behind this. Why fan should work only when CPU4
> (tmu_cpu0) is heated and not CPU5-7 (rest of cpu tmu's)?

Ok fan should work on all the thermal zone. To avoid thermal shutdown.

But I want to avoid scaling down of all the cores of cpu to low freq
as cooling-maps cross the alert temperature. For below example.
----
 map3 {
              trip = <&cpu1_alert3>;
              cooling-device = <&cpu0 0 2>;
 };
 map4 {
              trip = <&cpu1_alert3>;
              cooling-device = <&cpu4 0 2>;
 };

 map5 {
              trip = <&cpu1_alert4>;
              cooling-device = <&cpu0 3 7>;
 };
 map6 {
             trip = <&cpu1_alert4>;
             cooling-device = <&cpu4 3 12>;
 };

What I want to configure thermal zone as.

cpu0_thermal: cpu0-thermal {
     configure cluster of cpu[0-3]
     {
        tips
     }
     cooling map
     {
         device handle cpu[0-3] with frequency scaling at particular
alert temperature.
     }
}

cpu1_thermal: cpu1-thermal {
     configure cluster of cpu[4-7]
     {
        tips
     }
     cooling map
     {
         device handle cpu[4-7] with frequency scaling at particular
alert temperature.
     }
}

We can chose to configure rest of the thermal-zone on this approach.
Please share your thoughts.

Best Regards
-Anand Moon

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