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
