linux-kernel - Re: [PATCH 1/1] ARM: dts: dra7: Reduce cpu thermal shutdown temperature

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Date:   Tue, 16 May 2017 09:28:17 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     Ravikumar <rk@...com>
Cc:     "bcousson@...libre.com" <bcousson@...libre.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] ARM: dts: dra7: Reduce cpu thermal shutdown
 temperature

* Ravikumar <rk@...com> [170503 06:57]:
> Hi,
> 
> On Wednesday 12 April 2017 11:54 AM, Kattekola, Ravikumar wrote:
> > On dra7, as per TRM, the HW shutdown (TSHUT) temperature is hardcoded
> > to 123C and cannot be modified by SW. This means when the temperature
> > reaches 123C HW asserts TSHUT output which signals a warm reset.
> > This reset is held until the temperature goes below the TSHUT low (105C).
> > 
> > While in SW, the thermal driver continuously monitors current temperature
> > and takes decisions based on whether it reached an alert or a critical point.
> > The intention of setting a SW critical point is to prevent force reset by HW
> > and instead do an orderly_poweroff(). But if the SW critical temperature is
> > greater than or equal to that of HW then it defeats the purpose. To address
> > this and let SW take action before HW does keep the SW critical temperature
> > less than HW TSHUT value.
> > 
> > The value for SW critical temperature was chosen as 120C just to ensure
> > we give SW sometime before HW catches up.
> > 
> > Document reference
> > SPRUI30C – DRA75x, DRA74x Technical Reference Manual - November 2016
> > SPRUHZ6H - AM572x Technical Reference Manual - November 2016
> > 
> > Tested on:
> > DRA75x PG 2.0 Rev H EVM
> > 
> > Signed-off-by: Ravikumar Kattekola <rk@...com>
> > ---
> >   arch/arm/boot/dts/dra7.dtsi | 4 ++++
> >   1 file changed, 4 insertions(+)
> > 
> > diff --git a/arch/arm/boot/dts/dra7.dtsi b/arch/arm/boot/dts/dra7.dtsi
> > index 57892f2..e714466 100644
> > --- a/arch/arm/boot/dts/dra7.dtsi
> > +++ b/arch/arm/boot/dts/dra7.dtsi
> > @@ -2017,4 +2017,8 @@
> >   	coefficients = <0 2000>;
> >   };
> > +&cpu_crit {
> > +	temperature = <120000>; /* milli Celsius */
> > +};
> > +
> >   /include/ "dra7xx-clocks.dtsi"
> Ping..
> Any comments?

Seems good to have thanks. Applying into omap-for-v4.12/fixes.

Regards,

Tony