RE: [PATCH V15 RESEND 5/5] arm64: dts: imx: add i.MX8QXP thermal support

Anson Huang
2020-02-22T12:19:32Z

Hi, Daniel

> Subject: Re: [PATCH V15 RESEND 5/5] arm64: dts: imx: add i.MX8QXP thermal
> support
>
> On 22/02/2020 00:53, Anson Huang wrote:
> > Hi, Daniel
> >
>
> [ ... ]
>
> >>> +
> >>> + thermal_zones: thermal-zones {
> >>> + cpu-thermal0 {
> >>> + polling-delay-passive = <250>;
> >>> + polling-delay = <2000>;
> >>> + thermal-sensors = <&tsens IMX_SC_R_SYSTEM>;
> >>> + trips {
> >>> + cpu_alert0: trip0 {
> >>> + temperature = <107000>;
> >>> + hysteresis = <2000>;
> >>> + type = "passive";
> >>> + };
> >>
> >> May be you can add a 'hot' trip point before 'critical' for future
> >> use before reaching the emergency shutdown.
> >
> > The 'passive' trip is actually the 'hot' trip point you mentioned, and
> > I have combined it to below cooling map which will throttle cpu-freq when
> passive (hot) point is reached.
> > We all use 'passive' as 'hot' alarm and trigger cpu-freq throttle on i.MX
> platforms.
>
> Sorry, I'm not sure to get the point. A 'hot' trip point is not a 'passive' trip
> point. The 'hot' trip point is a critical temperature and a notification is raised
> [1][2].
>
> It is the last chance for the system to do something before the next trip point
> 'critical' is reached and where an emergency shutdown is done.
>
> The 'passive' trip point is the target temperature for mitigation in a normal
> situation when the system is loaded.

Ah, now I understand your point, as all i.MX SoCs ONLY support passive and critical
point, and never support the notification of hot trip point, so I think it should be OK
to leave i.MX8QXP same as other i.MX SoCs, if we plan to support hot trip point notification,
I will cut another patch for all i.MX SoCs, does it make sense to you? If yes, please help
review the V16 patch set I sent out.

thanks again for review,
Anson

>
> [1]
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