On Mon, Feb 24, 2020 at 06:23:28PM +0100, megous hlavni wrote:
> Hi,
>
> On Mon, Feb 24, 2020 at 06:06:20PM +0100, Daniel Lezcano wrote:
> > On 24/02/2020 17:54, Ondrej Jirman wrote:
> > > This enables passive cooling by down-regulating CPU voltage
> > > clocks = <&ccu CLK_C1CPUX>;
> > > @@ -1188,12 +1188,60 @@ cpu0_thermal: cpu0-thermal {
> > > polling-delay-passive = <0>;
> > > polling-delay = <0>;
> > > thermal-sensors = <&ths 0>;
> > > +
> > > + trips {
> > > + cpu0_hot: cpu-hot {
> > > + temperature = <80000>;
> > > + hysteresis = <2000>;
> > > + type = "passive";
> > > + };
> > > +
> > > + cpu0_very_hot: cpu-very-hot {
> > > + temperature = <100000>;
> > > + hysteresis = <0>;
> > > + type = "critical";
> > > + };
> > > + };
> > > +
> > > + cooling-maps {
> > > + cpu-hot-limit {
> > > + trip = <&cpu0_hot>;
> > > + cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> > > + <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> > > + <&cpu2 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> > > + <&cpu3 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
> > > + };
> > > + };
> > > };
> > >
> > > cpu1_thermal: cpu1-thermal {
> > > polling-delay-passive = <0>;
> >
> > No polling to mitigate?
>
> Polling to mitigate what?
>
> The driver is using interrupts whenever new reading is available, and
> notifies tz of the change. I don't have a reason to believe any new
> values are available from thermal sensor outside of the interrupt
> period.
To be more clear, new temperatures are available from the thermal sensor driver
at the rate of 4 per second, which should be enough to do quick adjustments to
the thermal zone/cooling device even for quick temperature rises.
https://elixir.bootlin.com/linux/v5.6-rc3/source/drivers/thermal/sun8i_thermal.c#L442
There's no slow/fast period depending on whether the cooling is active.
It's always fast and no polling of the thermal sensor is needed.
regards,
o.
> > > polling-delay = <0>;
> > > thermal-sensors = <&ths 1>;
> > > +
> > > + trips {
> > > + cpu1_hot: cpu-hot {
> > > + temperature = <80000>;
> > > + hysteresis = <2000>;
> > > + type = "passive";
> >
> > I'm curious, can you really reach this temperature with a cortex-a7
> > running at 1.2GHz max?
>
> That depends on ambient temperature. I'd say easily. My A83T is running
> iniside enclosed space with no cooling other than dissipating heat to
> the board.
>
> Anyway, I'm running my A83T boards at 1.8GHz. And A83T can run up to 2GHz
> at the best SoC bin.
>
> I'll probably submit updated cpufreq table at some point too, once I fix
> it up to use the SoC bin information.
>
> https://megous.com/git/linux/commit/?h=ths-5.6&id=171b7c3c3db98b5939d28d0c96b384edda95cec3
>
> regards,
> o.
>
> > > + };
> > > +
> > > + cpu1_very_hot: cpu-very-hot {
> > > + temperature = <100000>;
> > > + hysteresis = <0>;
> > > + type = "critical";
> > > + };
> > > + };
> > > +
> > > + cooling-maps {
> > > + cpu-hot-limit {
> > > + trip = <&cpu1_hot>;
> > > + cooling-device = <&cpu100 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> > > + <&cpu101 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> > > + <&cpu102 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> > > + <&cpu103 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
> > > + };
> > > + };
> > > };
> > >
> > > gpu_thermal: gpu-thermal {
> > >
> >
> >
> > --
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