RE: [PATCH] thermal: imx8mm: Add get_trend ops

[Anson Huang]

Hi, Daniel

> Subject: RE: [PATCH] thermal: imx8mm: Add get_trend ops
> 
> Hi, Daniel
> 
> > Subject: Re: [PATCH] thermal: imx8mm: Add get_trend ops
> >
> > On 25/05/2020 04:46, Anson Huang wrote:
> > > Hi, Daniel
> >
> > [ ... ]
> >
> > > I tried modifying the min/max to '2' in cooling map, it works that
> > > whenever cooling action is needed, the max cooling action will be
> > > applied. But I also noticed some behaviors which NOT as expected:
> > >

After looking further into the min/max setting in cooling map, it looks like NOT
suitable for our i.MX platforms, although OPP table is defined in DT, but the 
OPP
table is a full list of all available set points, and chips with different fuse 
settings
will ONLY enable some of set points in the OPP table, that introduces the 
trouble
of calculating the max state of cpufreq cooling, for example, on i.MX8MM, there 
are
3 set points defined in OPP table, but if the chip is with speed_grading fuse 
set to
1.6GHz, then ONLY 1.2GHz/1.6GHz are available for cpufreq, so the real max state
for cpufreq cooling is '1' actually, so how do I handle such scenario?

If thermal_zone_bind_cooling_device() can support parsing other macro new 
definition
like 'THERMAL_MAX_STATE' in DT, then in thermal_core.c, it can get real max 
state via
cdev->ops->get_max_state(cdev, _state) and set to lower/upper state, that 
will help
a lot for the case of our i.MX platforms. Do you have any suggestion?

122 opp-12 {
123 opp-hz = /bits/ 64 <12>;
124 opp-microvolt = <85>;
125 opp-supported-hw = <0xe>, <0x7>;
126 clock-latency-ns = <15>;
127 opp-suspend;
128 };
129
130 opp-16 {
131 opp-hz = /bits/ 64 <16>;
132 opp-microvolt = <90>;
133 opp-supported-hw = <0xc>, <0x7>;
134 clock-latency-ns = <15>;
135 opp-suspend;
136 };
137
138 opp-18 {
139 opp-hz = /bits/ 64 <18>;
140 opp-microvolt = <100>;
141 opp-supported-hw = <0x8>, <0x3>;
142 clock-latency-ns = <15>;
143 opp-suspend;
144 };

Thanks,
Anson

RE: [PATCH] thermal: imx8mm: Add get_trend ops

[Anson Huang]

Hi, Daniel

> Subject: Re: [PATCH] thermal: imx8mm: Add get_trend ops
> 
> On 25/05/2020 04:46, Anson Huang wrote:
> > Hi, Daniel
> 
> [ ... ]
> 
> > I tried modifying the min/max to '2' in cooling map, it works that
> > whenever cooling action is needed, the max cooling action will be
> > applied. But I also noticed some behaviors which NOT as expected:
> >
> > 1. to easy the test, I enable the " CONFIG_THERMAL_WRITABLE_TRIPS",
> > and just modify the passive trip threshold to trigger the cooling
> > action, this is much more easy then putting the board into an oven to
> > increase the SoC temperature or running many high loading test to
> > increase the temperature, but when I modify the passive trip threshold
> > to be lower than current temperature, the cooling action is NOT
> > triggered immediately, it is because the default step_wise governor
> > will NOT trigger the cooling action when the trend is
> > THERMAL_TREND_STABLE. But what expected is, when the temperature is
> > exceed the passive trip threshold, the cooling action can be triggered
> > immediately no matter the trend is stable or raising.
> 
> You are right, what is expected is, when the temperature exceeds the passive
> trip threshold, a cooling action happens, the trend is raising in this case.
> 
> But in your test, it is not what is happening: the trip point is changing, 
> not the
> temperature.
> 
> Probably, the cpufreq driver is at its lowest OPP, so there is no room for 
> more
> cooling effect when changing the trip point.
> 
> IMO, the test is not right as the trip point is decreased to a temperature 
> where
> actually the SoC is not hot.
> 
> If you want to test it easily, I recommend to use dhrystone, something like:
> 
>  dhrystone -t 6 -l 1
> 
> That will make your board to heat immediately.

Thanks, I understand. To aligned with the formal test method, I will inform our 
test
team to update the test case to meet the requirement.

> 
> > That
> > means we have to implement our own .get_trend callback?
> 
> From my POV it must disappear, because it has little meaning. The governor is
> the one which should be dealing with that and call the corresponding cooling
> index.

OK, I will use common .get_trend() implementation.

> 
> > 2. No margin for releasing the cooling action, for example, if cooling
> > action is triggered, when the temperature drops below the passive trip
> > threshold, the cooling action will be cancelled immediately, if SoC
> > keeps running at full performance, the temperature will increase very
> > soon, which may cause the SoC keep triggering/cancelling the cooling
> > action around the passive trip threshold. If there is a margin, the
> > situation will be much better.
> >
> > Do you have any idea/comment about them?
> 
> Yes, that is a good point. The hysteresis is supposed to do that. There is a 
> work
> done by Andrzej Pietrasiewicz to disable / enable the thermal zones [1]. I 
> think
> we should be able to fix that after the changes are done.

OK, then I will wait for this change. So to apply MAX cooling action 
immediately,
all expected changes for i.MX platforms are to assign min/max cooling index in
DT cooling map, I will summit a patch set then.

Thanks,
Anson.

Re: [PATCH] thermal: imx8mm: Add get_trend ops

[Daniel Lezcano]

On 25/05/2020 04:46, Anson Huang wrote:
> Hi, Daniel

[ ... ]

> I tried modifying the min/max to '2' in cooling map, it works that
> whenever cooling action is needed, the max cooling action will be
> applied. But I also noticed some behaviors which NOT as expected:
> 
> 1. to easy the test, I enable the " CONFIG_THERMAL_WRITABLE_TRIPS",
> and just modify the passive trip threshold to trigger the cooling
> action, this is much more easy then putting the board into an oven to
> increase the SoC temperature or running many high loading test to
> increase the temperature, but when I modify the passive trip
> threshold to be lower than current temperature, the cooling action is
> NOT triggered immediately, it is because the default step_wise
> governor will NOT trigger the cooling action when the trend is
> THERMAL_TREND_STABLE. But what expected is, when the temperature is
> exceed the passive trip threshold, the cooling action can be 
> triggered immediately no matter the trend is stable or raising.

You are right, what is expected is, when the temperature exceeds the
passive trip threshold, a cooling action happens, the trend is raising
in this case.

But in your test, it is not what is happening: the trip point is
changing, not the temperature.

Probably, the cpufreq driver is at its lowest OPP, so there is no room
for more cooling effect when changing the trip point.

IMO, the test is not right as the trip point is decreased to a
temperature where actually the SoC is not hot.

If you want to test it easily, I recommend to use dhrystone, something like:

 dhrystone -t 6 -l 1

That will make your board to heat immediately.

> That
> means we have to implement our own .get_trend callback?

>From my POV it must disappear, because it has little meaning. The
governor is the one which should be dealing with that and call the
corresponding cooling index.

> 2. No margin for releasing the cooling action, for example, if
> cooling action is triggered, when the temperature drops below the
> passive trip threshold, the cooling action will be cancelled
> immediately, if SoC keeps running at full performance, the
> temperature will increase very soon, which may cause the SoC keep
> triggering/cancelling the cooling action around the passive trip
> threshold. If there is a margin, the situation will be much better.
> 
> Do you have any idea/comment about them?

Yes, that is a good point. The hysteresis is supposed to do that. There
is a work done by Andrzej Pietrasiewicz to disable / enable the thermal
zones [1]. I think we should be able to fix that after the changes are done.

  -- Daniel

[1] https://www.spinics.net/lists/netdev/msg644762.html


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RE: [PATCH] thermal: imx8mm: Add get_trend ops

[Anson Huang]

Hi, Daniel


> Subject: RE: [PATCH] thermal: imx8mm: Add get_trend ops
> 
> Hi, Daniel
> 
> > Subject: Re: [PATCH] thermal: imx8mm: Add get_trend ops
> >
> > On 23/05/2020 02:35, Anson Huang wrote:
> > > Hi, Daniel
> > >
> > >
> > >> Subject: Re: [PATCH] thermal: imx8mm: Add get_trend ops
> > >>
> > >> On 13/05/2020 04:58, Anson Huang wrote:
> > >>> Add get_trend ops for i.MX8MM thermal to apply fast cooling
> > >>> mechanism, when temperature exceeds passive trip point, the
> > >>> highest cooling action will be applied, and when temperature drops
> > >>> to lower than the margin below passive trip point, the lowest
> > >>> cooling action will be applied.
> > >>
> > >> You are not describing what is the goal of this change.
> > >
> > > The goal of this change is to make sure whenever temperature exceeds
> > > passive trip point, the highest cooling action will be applied
> > > immediately, e.g., if there are many cpufreq OPP, the default
> > > cooling will be step by step, it will take some more rounds to make
> > > cpufreq drop to
> > lowest OPP, while on i.MX, we expect the cpufreq drop to lowest OPP
> > immediately.
> >
> > Whatever the slope of the temperature increase?
> 
> Yes.
> 
> >
> > >> IIUC, the resulting change will be an on/off action. The thermal
> > >> zone is mitigated with the highest cooling effect, so the lowest
> > >> OPP, then the temperature trend is stable until it goes below the
> > >> trip - margin where the mitigation is stopped.
> > >
> > > Yes, your understanding is correctly, once the temperature exceeds
> > > passive trip point, the highest cooling action will be applied
> > > immediately and then it will be stable there until temperature drop
> > > to trip - margin, then the cooling action will be cancelled, the
> > > margin is to avoid
> > the back and forth near the passive trip point.
> > >
> > >>
> > >> Except, I'm missing something, setting a trip point with a 1
> > >> hysteresis and a cooling map min/max set to the highest opp will
> > >> result on
> > the same.
> > >
> > > Yes setting cooling map min/max cooling state to highest OPP will
> > > make the highest cooling action applied immediately, and to have the
> > > function of cooling action being cancelled when temperature drops to
> > > trip - margin, I have to define another trip point, say passive trip
> > > point is 85000, and cooling map min/max set to highest OPP in
> > > passive trip point then add another trip point named "active" with
> > > 75000, and
> > without any cooling map in it, right?
> >
> > May be I misunderstood but only the change as below is needed. No need
> > to add a trip point, especially an 'active' trip which is a for an
> > active cooling device like a fan.
> >
> > diff --git a/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> > b/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> > index cc7152ecedd9..bea263bd06b4 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> > +++ b/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> > @@ -231,10 +231,10 @@ cooling-maps {
> > map0 {
> > trip = <_alert0>;
> > cooling-device =
> > -   <_0 THERMAL_NO_LIMIT
> > THERMAL_NO_LIMIT>,
> > -   <_1 THERMAL_NO_LIMIT
> > THERMAL_NO_LIMIT>,
> > -   <_2 THERMAL_NO_LIMIT
> > THERMAL_NO_LIMIT>,
> > -   <_3 THERMAL_NO_LIMIT
> > THERMAL_NO_LIMIT>;
> > +   <_0 2 2>,
> > +   <_1 2 2>,
> > +   <_2 2 2>,
> > +   <_3 2 2>
> > };
> > };
> > };
> >
> >
> 
> Thanks, I will have a try to see if it meets our expectation.

I tried modifying the min/max to '2' in cooling map, it works that whenever 
cooling
action is needed, the max cooling action will be applied. But I also noticed 
some behaviors
which NOT as expected:

1. to easy the test, I enable the " CONFIG_THERMAL_W

RE: [PATCH] thermal: imx8mm: Add get_trend ops

[Anson Huang]

Hi, Daniel

> Subject: Re: [PATCH] thermal: imx8mm: Add get_trend ops
> 
> On 23/05/2020 02:35, Anson Huang wrote:
> > Hi, Daniel
> >
> >
> >> Subject: Re: [PATCH] thermal: imx8mm: Add get_trend ops
> >>
> >> On 13/05/2020 04:58, Anson Huang wrote:
> >>> Add get_trend ops for i.MX8MM thermal to apply fast cooling
> >>> mechanism, when temperature exceeds passive trip point, the highest
> >>> cooling action will be applied, and when temperature drops to lower
> >>> than the margin below passive trip point, the lowest cooling action
> >>> will be applied.
> >>
> >> You are not describing what is the goal of this change.
> >
> > The goal of this change is to make sure whenever temperature exceeds
> > passive trip point, the highest cooling action will be applied
> > immediately, e.g., if there are many cpufreq OPP, the default cooling
> > will be step by step, it will take some more rounds to make cpufreq drop to
> lowest OPP, while on i.MX, we expect the cpufreq drop to lowest OPP
> immediately.
> 
> Whatever the slope of the temperature increase?

Yes.

> 
> >> IIUC, the resulting change will be an on/off action. The thermal zone
> >> is mitigated with the highest cooling effect, so the lowest OPP, then
> >> the temperature trend is stable until it goes below the trip - margin
> >> where the mitigation is stopped.
> >
> > Yes, your understanding is correctly, once the temperature exceeds
> > passive trip point, the highest cooling action will be applied
> > immediately and then it will be stable there until temperature drop to
> > trip - margin, then the cooling action will be cancelled, the margin is to 
> > avoid
> the back and forth near the passive trip point.
> >
> >>
> >> Except, I'm missing something, setting a trip point with a 1
> >> hysteresis and a cooling map min/max set to the highest opp will result on
> the same.
> >
> > Yes setting cooling map min/max cooling state to highest OPP will make
> > the highest cooling action applied immediately, and to have the
> > function of cooling action being cancelled when temperature drops to
> > trip - margin, I have to define another trip point, say passive trip
> > point is 85000, and cooling map min/max set to highest OPP in passive
> > trip point then add another trip point named "active" with 75000, and
> without any cooling map in it, right?
> 
> May be I misunderstood but only the change as below is needed. No need to
> add a trip point, especially an 'active' trip which is a for an active cooling
> device like a fan.
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> b/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> index cc7152ecedd9..bea263bd06b4 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> @@ -231,10 +231,10 @@ cooling-maps {
>   map0 {
>   trip = <_alert0>;
>   cooling-device =
> - <_0 THERMAL_NO_LIMIT
> THERMAL_NO_LIMIT>,
> - <_1 THERMAL_NO_LIMIT
> THERMAL_NO_LIMIT>,
> - <_2 THERMAL_NO_LIMIT
> THERMAL_NO_LIMIT>,
> - <_3 THERMAL_NO_LIMIT
> THERMAL_NO_LIMIT>;
> + <_0 2 2>,
> + <_1 2 2>,
> + <_2 2 2>,
> + <_3 2 2>
>   };
>   };
>   };
> 
> 

Thanks, I will have a try to see if it meets our expectation.

Anson

Re: [PATCH] thermal: imx8mm: Add get_trend ops

[Daniel Lezcano]

On 23/05/2020 02:35, Anson Huang wrote:
> Hi, Daniel
> 
> 
>> Subject: Re: [PATCH] thermal: imx8mm: Add get_trend ops
>>
>> On 13/05/2020 04:58, Anson Huang wrote:
>>> Add get_trend ops for i.MX8MM thermal to apply fast cooling mechanism,
>>> when temperature exceeds passive trip point, the highest cooling
>>> action will be applied, and when temperature drops to lower than the
>>> margin below passive trip point, the lowest cooling action will be
>>> applied.
>>
>> You are not describing what is the goal of this change.
> 
> The goal of this change is to make sure whenever temperature exceeds passive 
> trip point,
> the highest cooling action will be applied immediately, e.g., if there are 
> many cpufreq OPP,
> the default cooling will be step by step, it will take some more rounds to 
> make cpufreq drop
> to lowest OPP, while on i.MX, we expect the cpufreq drop to lowest OPP 
> immediately.

Whatever the slope of the temperature increase?

>> IIUC, the resulting change will be an on/off action. The thermal zone is
>> mitigated with the highest cooling effect, so the lowest OPP, then the
>> temperature trend is stable until it goes below the trip - margin where the
>> mitigation is stopped.
> 
> Yes, your understanding is correctly, once the temperature exceeds passive 
> trip point,
> the highest cooling action will be applied immediately and then it will be 
> stable there
> until temperature drop to trip - margin, then the cooling action will be 
> cancelled, the
> margin is to avoid the back and forth near the passive trip point.
> 
>>
>> Except, I'm missing something, setting a trip point with a 1 hysteresis 
>> and
>> a cooling map min/max set to the highest opp will result on the same.
> 
> Yes setting cooling map min/max cooling state to highest OPP will make the 
> highest
> cooling action applied immediately, and to have the function of cooling 
> action being
> cancelled when temperature drops to trip - margin, I have to define another 
> trip point,
> say passive trip point is 85000, and cooling map min/max set to highest OPP 
> in passive
> trip point then add another trip point named "active" with 75000, and without 
> any
> cooling map in it, right?

May be I misunderstood but only the change as below is needed. No need
to add a trip point, especially an 'active' trip which is a for an
active cooling device like a fan.

diff --git a/arch/arm64/boot/dts/freescale/imx8mm.dtsi
b/arch/arm64/boot/dts/freescale/imx8mm.dtsi
index cc7152ecedd9..bea263bd06b4 100644
--- a/arch/arm64/boot/dts/freescale/imx8mm.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8mm.dtsi
@@ -231,10 +231,10 @@ cooling-maps {
map0 {
trip = <_alert0>;
cooling-device =
-   <_0 THERMAL_NO_LIMIT 
THERMAL_NO_LIMIT>,
-   <_1 THERMAL_NO_LIMIT 
THERMAL_NO_LIMIT>,
-   <_2 THERMAL_NO_LIMIT 
THERMAL_NO_LIMIT>,
-   <_3 THERMAL_NO_LIMIT 
THERMAL_NO_LIMIT>;
+   <_0 2 2>,
+   <_1 2 2>,
+   <_2 2 2>,
+   <_3 2 2>
};
};
};


> If yes, then I think I can try to make the changes in DT instead of thermal 
> driver. 


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RE: [PATCH] thermal: imx8mm: Add get_trend ops

[Anson Huang]

Hi, Daniel


> Subject: Re: [PATCH] thermal: imx8mm: Add get_trend ops
> 
> On 13/05/2020 04:58, Anson Huang wrote:
> > Add get_trend ops for i.MX8MM thermal to apply fast cooling mechanism,
> > when temperature exceeds passive trip point, the highest cooling
> > action will be applied, and when temperature drops to lower than the
> > margin below passive trip point, the lowest cooling action will be
> > applied.
> 
> You are not describing what is the goal of this change.

The goal of this change is to make sure whenever temperature exceeds passive 
trip point,
the highest cooling action will be applied immediately, e.g., if there are many 
cpufreq OPP,
the default cooling will be step by step, it will take some more rounds to make 
cpufreq drop
to lowest OPP, while on i.MX, we expect the cpufreq drop to lowest OPP 
immediately.

> 
> IIUC, the resulting change will be an on/off action. The thermal zone is
> mitigated with the highest cooling effect, so the lowest OPP, then the
> temperature trend is stable until it goes below the trip - margin where the
> mitigation is stopped.

Yes, your understanding is correctly, once the temperature exceeds passive trip 
point,
the highest cooling action will be applied immediately and then it will be 
stable there
until temperature drop to trip - margin, then the cooling action will be 
cancelled, the
margin is to avoid the back and forth near the passive trip point.

> 
> Except, I'm missing something, setting a trip point with a 1 hysteresis 
> and
> a cooling map min/max set to the highest opp will result on the same.

Yes setting cooling map min/max cooling state to highest OPP will make the 
highest
cooling action applied immediately, and to have the function of cooling action 
being
cancelled when temperature drops to trip - margin, I have to define another 
trip point,
say passive trip point is 85000, and cooling map min/max set to highest OPP in 
passive
trip point then add another trip point named "active" with 75000, and without 
any
cooling map in it, right?

If yes, then I think I can try to make the changes in DT instead of thermal 
driver. 

Thanks,
Anson

Re: [PATCH] thermal: imx8mm: Add get_trend ops

[Daniel Lezcano]

On 13/05/2020 04:58, Anson Huang wrote:
> Add get_trend ops for i.MX8MM thermal to apply fast cooling
> mechanism, when temperature exceeds passive trip point, the
> highest cooling action will be applied, and when temperature
> drops to lower than the margin below passive trip point, the
> lowest cooling action will be applied.

You are not describing what is the goal of this change.

IIUC, the resulting change will be an on/off action. The thermal zone is
mitigated with the highest cooling effect, so the lowest OPP, then the
temperature trend is stable until it goes below the trip - margin where
the mitigation is stopped.

Except, I'm missing something, setting a trip point with a 1
hysteresis and a cooling map min/max set to the highest opp will result
on the same.


> Signed-off-by: Anson Huang 
> ---
>  drivers/thermal/imx8mm_thermal.c | 27 +++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/thermal/imx8mm_thermal.c 
> b/drivers/thermal/imx8mm_thermal.c
> index e6061e2..8f6a0b8 100644
> --- a/drivers/thermal/imx8mm_thermal.c
> +++ b/drivers/thermal/imx8mm_thermal.c
> @@ -38,6 +38,8 @@
>  #define TMU_VER1 0x1
>  #define TMU_VER2 0x2
>  
> +#define IMX_TEMP_COOL_MARGIN 1
> +
>  struct thermal_soc_data {
>   u32 num_sensors;
>   u32 version;
> @@ -103,8 +105,33 @@ static int tmu_get_temp(void *data, int *temp)
>   return tmu->socdata->get_temp(data, temp);
>  }
>  
> +static int tmu_get_trend(void *p, int trip, enum thermal_trend *trend)
> +{
> + struct tmu_sensor *sensor = p;
> + int trip_temp, temp, ret;
> +
> + if (!sensor->tzd)
> + return -EINVAL;
> +
> + ret = sensor->tzd->ops->get_trip_temp(sensor->tzd, trip, _temp);
> + if (ret)
> + return ret;
> +
> + temp = READ_ONCE(sensor->tzd->temperature);
> +
> + if (temp > trip_temp)
> + *trend = THERMAL_TREND_RAISE_FULL;
> + else if (temp < (trip_temp - IMX_TEMP_COOL_MARGIN))
> + *trend = THERMAL_TREND_DROP_FULL;
> + else
> + *trend = THERMAL_TREND_STABLE;
> +
> + return 0;
> +}
> +
>  static struct thermal_zone_of_device_ops tmu_tz_ops = {
>   .get_temp = tmu_get_temp,
> + .get_trend = tmu_get_trend,
>  };
>  
>  static void imx8mm_tmu_enable(struct imx8mm_tmu *tmu, bool enable)
> 


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