On 17/12/2020 20:01, Dmitry Osipenko wrote:
> 17.12.2020 21:28, Daniel Lezcano пишет:
>> On 17/12/2020 19:06, Dmitry Osipenko wrote:
>>> Enable CPU voltage scaling and thermal throttling on Tegra20 Ventana board.
>>>
>>> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
>>> ---
>>> arch/arm/boot/dts/tegra20-ventana.dts | 40 ++++++++++++++++++++++++++-
>>> 1 file changed, 39 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/boot/dts/tegra20-ventana.dts b/arch/arm/boot/dts/tegra20-ventana.dts
>>> index 14ace2ef749c..c2d9f38960bc 100644
>>> --- a/arch/arm/boot/dts/tegra20-ventana.dts
>>> +++ b/arch/arm/boot/dts/tegra20-ventana.dts
>>> @@ -2,8 +2,10 @@
>>> /dts-v1/;
>>>
>>> #include <dt-bindings/input/input.h>
>>> +#include <dt-bindings/thermal/thermal.h>
>>> #include "tegra20.dtsi"
>>> #include "tegra20-cpu-opp.dtsi"
>>> +#include "tegra20-cpu-opp-microvolt.dtsi"
>>>
>>> / {
>>> model = "NVIDIA Tegra20 Ventana evaluation board";
>>> @@ -527,9 +529,10 @@ ldo_rtc {
>>> };
>>> };
>>>
>>> - temperature-sensor@4c {
>>> + nct1008: temperature-sensor@4c {
>>> compatible = "onnn,nct1008";
>>> reg = <0x4c>;
>>> + #thermal-sensor-cells = <1>;
>>> };
>>> };
>>>
>>> @@ -615,10 +618,13 @@ clk32k_in: clock@0 {
>>>
>>> cpus {
>>> cpu0: cpu@0 {
>>> + cpu-supply = <&vdd_cpu>;
>>> operating-points-v2 = <&cpu0_opp_table>;
>>> + #cooling-cells = <2>;
>>> };
>>>
>>> cpu@1 {
>>> + cpu-supply = <&vdd_cpu>;
>>> operating-points-v2 = <&cpu0_opp_table>;
>>> };
>>> };
>>> @@ -717,4 +723,36 @@ sound {
>>> <&tegra_car TEGRA20_CLK_CDEV1>;
>>> clock-names = "pll_a", "pll_a_out0", "mclk";
>>> };
>>> +
>>> + thermal-zones {
>>> + cpu-thermal {
>>> + polling-delay-passive = <1000>; /* milliseconds */
>>> + polling-delay = <5000>; /* milliseconds */
>>> +
>>> + thermal-sensors = <&nct1008 1>;
>>> +
>>> + trips {
>>> + trip0: cpu-alert0 {
>>> + /* start throttling at 50C */
>>> + temperature = <50000>;
>>> + hysteresis = <200>;
>>
>> Did you mean <2000> ?
>
> The <200> is correct.
>
> Please see this commit for example:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2b22393b27670b45a2c870bce3df6579efd9a86a
Ok, thanks for the pointer.
>>> + type = "passive";
>>> + };
>>> +
>>> + trip1: cpu-crit {
>>> + /* shut down at 60C */
>>> + temperature = <60000>;
>>> + hysteresis = <2000>;
>>
>> I think you can drop the hysteresis here, when the critical temperature
>> is reached, there is an emergency shutdown.
>
> Yes, perhaps you're right. Hysteresis doesn't make sense for a critical
> trip. I'll improve it in the next revision, thanks.
>
>> 50°C and 60°C sound very low values, no ?
>
> Tegra20 CPU is very cold in comparison to later generations, it should
> stay under 50°C even at a full load.
Interesting, thanks.
>>> + type = "critical";
>>> + };
>>> + };
>>> +
>>> + cooling-maps {
>>> + map0 {
>>> + trip = <&trip0>;
>>> + cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
>>
>> You should add all CPUs here.
>
>
> All CPU cores are coupled on Tegra in regards to CPUFreq, hence I think
> it won't make any difference if secondary CPU cores will be added here,
> isn't it?
The explanation is in the description of commit ef4734500407ce4d
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