linux-kernel - Re: [PATCH 2/2] ARM: dts: rockchip: Configure the GPU thermal zone for mickey

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Date:   Mon, 20 May 2019 14:21:02 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Heiko Stuebner <heiko@...ech.de>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        devicetree@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] ARM: dts: rockchip: Configure the GPU thermal zone
 for mickey

On Mon, May 20, 2019 at 01:21:33PM -0700, Doug Anderson wrote:
> Hi,
> 
> On Mon, May 20, 2019 at 10:01 AM Matthias Kaehlcke <mka@...omium.org> wrote:
> >
> > mickey crams a lot of hardware into a tiny package, which requires
> > more aggressive thermal throttling than for devices with a larger
> > footprint. Configure the GPU thermal zone to throttle the GPU
> > progressively at temperatures >= 60°C. Heat dissipated by the
> > CPUs also affects the GPU temperature, hence we cap the CPU
> > frequency to 1.4 GHz for temperatures above 65°C. Further throttling
> > of the CPUs may be performed by the CPU thermal zone.
> >
> > The configuration matches that of the downstram Chrome OS 3.14
> 
> s/downstram/downstream

ack

> 
> > +       cooling-maps {
> > +               /* After 1st level throttle the GPU down to as low as 400 MHz */
> > +               gpu_warmish_limit_gpu {
> > +                       trip = <&gpu_alert_warmish>;
> > +                       cooling-device = <&gpu THERMAL_NO_LIMIT 1>;
> 
> As per my comment in patch #1, you are probably ending up throttling
> to 500 MHz, not 400 MHz.  Below will all have similar problems unless
> we actually delete the 500 MHz operating point.

Thanks for pointing that out. As per disussion on patch #1 we'll
disable the 500 MHz OPP to stay in sync with downstream and avoid
problems in case someone decides to re-purpose NPLL.

> > +               };
> > +
> > +               /*
> > +                * Slightly after we throttle the GPU, we'll also make sure that
> > +                * the CPU can't go faster than 1.4 GHz.  Note that we won't
> > +                * throttle the CPU lower than 1.4 GHz due to GPU heat--we'll
> > +                * let the CPU do the rest itself.
> > +                */
> > +               gpu_warm_limit_cpu {
> > +                       trip = <&gpu_alert_warm>;
> > +                       cooling-device = <&cpu0 4 4>;
> 
> Shouldn't you list cpu1, cpu2, and cpu3 too?  That'd match what
> upstream did elsewhere in this file?

ack, should have noticed, I 'yelled' at others before for not doing this ...