linux-kernel - Re: [PATCH 2/4] arm64: dts: qcom: x1e80100: Apply consistent critical thermal shutdown

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Message-ID: <Z7YGnN9XwDqOpwc4@linaro.org>
Date: Wed, 19 Feb 2025 17:28:12 +0100
From: Stephan Gerhold <stephan.gerhold@...aro.org>
To: Johan Hovold <johan@...nel.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Abel Vesa <abel.vesa@...aro.org>,
	Rajendra Nayak <quic_rjendra@...cinc.com>,
	Akhil P Oommen <quic_akhilpo@...cinc.com>,
	linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Neil Armstrong <neil.armstrong@...aro.org>
Subject: Re: [PATCH 2/4] arm64: dts: qcom: x1e80100: Apply consistent
 critical thermal shutdown

On Wed, Feb 19, 2025 at 04:36:45PM +0100, Johan Hovold wrote:
> On Wed, Feb 19, 2025 at 12:36:19PM +0100, Stephan Gerhold wrote:
> > The firmware configures the TSENS controller with a maximum temperature of
> > 120°C. When reaching that temperature, the hardware automatically triggers
> > a reset of the entire platform. Some of the thermal zones in x1e80100.dtsi
> > use a critical trip point of 125°C. It's impossible to reach those.
> > 
> > It's preferable to shut down the system cleanly before reaching the
> > hardware trip point. Make the critical temperature trip points consistent
> > by setting all of them to 115°C and apply a consistent hysteresis.
> > The ACPI tables also specify 115°C as critical shutdown temperature.
> > 
> > Cc: stable@...r.kernel.org
> > Fixes: 4e915987ff5b ("arm64: dts: qcom: x1e80100: Enable tsens and thermal zone nodes")
> > Signed-off-by: Stephan Gerhold <stephan.gerhold@...aro.org>
> 
> > @@ -8483,7 +8483,7 @@ trip-point1 {
> >  				};
> >  
> >  				cpu-critical {
> > -					temperature = <110000>;
> > +					temperature = <115000>;
> 
> Have you asked the authors where this lower limit came from (or
> determined it was just copy pasta some other way)?
> 

I haven't asked before sending the patch, but it looks like copy-paste
from sm8550.dtsi. That one also has these weird double passive trip
points for the CPU, which are dropped for x1e80100.dtsi in the last
patch of this series. Rajendra and Abel are in the Cc though in case
they would like to comment. :-)

> >  					hysteresis = <1000>;
> >  					type = "critical";
> >  				};
> 
> > @@ -8737,7 +8737,7 @@ trip-point0 {
> >  				};
> >  
> >  				video-critical {
> > -					temperature = <125000>;
> > +					temperature = <115000>;
> >  					hysteresis = <1000>;
> >  					type = "critical";
> >  				};
> 
> Ok, make sense to backport the first patch as well then.
> 

Exactly. :D

> Looks good to me:
> 
> Reviewed-by: Johan Hovold <johan+linaro@...nel.org>

Thanks!
Stephan