The SOC runs unthrotlled slowly to 80 degrees. This takes minutes. Polling interval 1 second or less does not matter much when looking at these temperature rise times After that in more then an hour it slowly creeps up to 85. I believe the design is so that the SOC, under normal circumstances, can run at 1.35 GHz without throttling frequency, without heatsink. It just needs a safeguard for different circumstances. Most of these SOCs can also run in industrial grade circumstances, which means up to 85 degrees ambient temperature already . If not industrial then this would be 60 degrees ambient already But only someone at Mediatek can confirm this Get BlueMail for Android On Jun 24, 2021, 12:21 PM, at 12:21 PM, Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> wrote: >On 24/06/2021 11:59, Eric Woudstra wrote: >> >> For Marvell: >> >> >https://www.google.com/url?sa=t&source=web&rct=j&url=https://wiki.kobol.io/helios4/files/som/brochure_a38x_microsom_2017-09-05.pdf >> >> Armada38x maximum die temperature 115 degrees Celcius. They really >get hotter then 100. >> >> But for mt7622 I cannot find this value > >Found that: > >https://download.kamami.pl/p579344-MT7622A_Datasheet_for_BananaPi_Only%281%29.pdf > >Chapter 3.3 - Thermal Characteristics > >Given the values I suggest: > > - Passive - 80°C > > - Hot - 90°C > > - Critical - 100°C > >And passive polling set to 250ms. > >It sounds like the sensor is not supporting the interrupt mode yet, so >a >big gap is needed with the Tj IMO to give the time to detect the trip >point crossing with the polling. > >> Get BlueMail for Android >> >> On Jun 23, 2021, 10:08 PM, at 10:08 PM, Daniel Lezcano ><daniel.lezcano@xxxxxxxxxx> wrote: >>> On 23/06/2021 20:43, Eric Woudstra wrote: >>>> >>>> I choose "hot" before, because 87 degrees seems ok to start >frequency >>>> throttling. But, yes, it should be passive. >>>> >>>> 87 is still quite low if I compare this temperature with the >>>> wrt3200acm Marvell dual core arm soc. They even went above 100 >>>> degrees so I feel for an arm processor inside a router box it is >fine >>>> to use 87 degrees But maybe someone at Mediatek can give some more >>>> details about operating temperatures. >>> >>> Sometimes, the SoC vendor puts a high temperature in the DT just to >>> export the thermal zone and deal with it from userspace. So putting >the >>> high temp allow the userspace (usually a thermal engine - Android >>> stuff) >>> to deal with the mitigation without a kernel interaction. >>> >>> Having more than 100°C could be this kind of setup. Only the >operating >>> temperature from the hardware documentation will tell the safe >>> temperature for the silicon. >>> >>> IMO, 77°C is a good compromise until getting the documented temp. >87°C >>> sounds to me a bit too hot. >>> >>>> It may be possible to leave the active map in the device tree as >some >>>> users of the bananapi might choose to install a fan as it is one of >>>> the options. >>> >>> The active trip only makes sense if the cooling device is a fan (or >any >>> active device), so the mapping points to a fan node, like: >>> >>> >https://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux.git/tree/arch/arm64/boot/dts/rockchip/rk3399-khadas-edge.dtsi#n192 >>> >>> If there is no such [pwm] fan output on the board, no active trip >point >>> should be added. >>> >>>> Get BlueMail for Android >>>> >>>> On Jun 23, 2021, 5:58 PM, at 5:58 PM, Daniel Lezcano >>>> <daniel.lezcano@xxxxxxxxxx> wrote: >>>>> On 23/06/2021 17:35, Eric Woudstra wrote: >>>>>> It is only useful to set 1 map with the regulated temperature for >>>>>> cpu frequency throttling. Same as in the kernel document >>>>>> example. >>>>>> >>>>>> >>>>>> It has no use to set frequency scaling on 2 different >>>>>> temperature trip points, as the lowest one makes sure the higher >>>>>> one(s) are never reached. >>>>> >>>>> I looked more closely the DT and there is a misunderstanding of >>>>> the thermal framework in the definition. >>>>> >>>>> There is one trip point with the passive type and the cpu cooling >>>>> device, followed by a second trip point with the active type *but* >>>>> the same cpu cooling device. That is wrong. >>>>> >>>>> And finally, there is the hot trip point as a third mapping and >>>>> the same cooling device. >>>>> >>>>> The hot trip point is only there to notify userspace and let it >>>>> take an immediate action to prevent an emergency shutdown when >>>>> reaching the critical temperature. >>>>> >>>>>> It can be applied only at 1 trip point. Multiple trip points is >>>>>> only usefully for fan control to make sure the fan is not too >>>>>> noisy when it is not necessary to be noisy. >>>>>> >>>>>> >>>>>> The CPU will almost come to a dead stop when it starts to pass >>>>>> the lowest thermal map with frequency throttling. >>>>>> >>>>>> This is why it is a bug and needs a fix, not only adjustment. >>>>> >>>>> Yes, you are right. It should be something like (verbatim copy): >>>>> >>>>> diff --git a/arch/arm64/boot/dts/mediatek/mt7622.dtsi >>>>> b/arch/arm64/boot/dts/mediatek/mt7622.dtsi index >>>>> 890a942ec608..88c81d24f4ff 100644 --- >>>>> a/arch/arm64/boot/dts/mediatek/mt7622.dtsi +++ >>>>> b/arch/arm64/boot/dts/mediatek/mt7622.dtsi @@ -136,24 +136,18 @@ >>>>> secmon_reserved: secmon@43000000 { >>>>> >>>>> thermal-zones { cpu_thermal: cpu-thermal { - >>>>> polling-delay-passive = <1000>; + polling-delay-passive = <250>; > >>>>> polling-delay = <1000>; >>>>> >>>>> thermal-sensors = <&thermal 0>; >>>>> >>>>> trips { cpu_passive: cpu-passive { - temperature = <47000>; + >>>>> temperature = <77000>; hysteresis = <2000>; type = "passive"; }; >>>>> >>>>> - cpu_active: cpu-active { - temperature = <67000>; - >>>>> hysteresis = <2000>; - type = "active"; - }; - cpu_hot: >>>>> cpu-hot { temperature = <87000>; hysteresis = <2000>; @@ -173,18 >>>>> +167,6 @@ map0 { cooling-device = <&cpu0 THERMAL_NO_LIMIT >>>>> THERMAL_NO_LIMIT>, <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>; }; - > >>>>> - map1 { - trip = <&cpu_active>; - cooling-device = >>>>> <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>, - <&cpu1 >>>>> THERMAL_NO_LIMIT THERMAL_NO_LIMIT>; - }; - - map2 { - >>>>> trip = <&cpu_hot>; - cooling-device = <&cpu0 THERMAL_NO_LIMIT >>>>> THERMAL_NO_LIMIT>, - <&cpu1 THERMAL_NO_LIMIT >>>>> THERMAL_NO_LIMIT>; - }; }; }; }; >>>>> >>>>> >>>>> -- <http://www.linaro.org/> Linaro.org │ Open source software for >>>>> ARM SoCs >>>>> >>>>> Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | >>>>> <http://twitter.com/#!/linaroorg> Twitter | >>>>> <http://www.linaro.org/linaro-blog/> Blog >>>> >>> >>> >>> -- >>> <http://www.linaro.org/> Linaro.org │ Open source software for ARM >SoCs >>> >>> Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | >>> <http://twitter.com/#!/linaroorg> Twitter | >>> <http://www.linaro.org/linaro-blog/> Blog >> > > >-- ><http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs > >Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | ><http://twitter.com/#!/linaroorg> Twitter | ><http://www.linaro.org/linaro-blog/> Blog
