linux-kernel - Re: [PATCH V2] ARM: dts: omap3: Add cpu trips and cooling map for omap34/36 families

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Message-ID: <20200818085853.GO2994@atomide.com>
Date:   Tue, 18 Aug 2020 11:58:53 +0300
From:   Tony Lindgren <tony@...mide.com>
To:     Andreas Kemnade <andreas@...nade.info>
Cc:     Adam Ford <aford173@...il.com>,
        Linux-OMAP <linux-omap@...r.kernel.org>,
        Adam Ford-BE <aford@...conembedded.com>,
        Benoît Cousson <bcousson@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "H. Nikolaus Schaller" <hns@...delico.com>
Subject: Re: [PATCH V2] ARM: dts: omap3: Add cpu trips and cooling map for
 omap34/36 families

* Andreas Kemnade <andreas@...nade.info> [200817 20:15]:
> On Mon, 17 Aug 2020 15:02:27 -0500
> Adam Ford <aford173@...il.com> wrote:
> 
> > On Mon, Aug 17, 2020 at 2:59 PM Andreas Kemnade <andreas@...nade.info> wrote:
> > >
> > > On Mon, 17 Aug 2020 08:39:31 -0500
> > > Adam Ford <aford173@...il.com> wrote:
> > >  
> > > > The OMAP3530, OMAP3630, and DM3730 all show thresholds of 90C and 105C
> > > > depending on commercial or industrial temperature ratings.
> > > >
> > > > This patch expands the thermal information to include the limits of 90
> > > > and 105C for alert and critical.  It sets the coolings-cells for the
> > > > 34xx and 36xx CPU's which both point to omap3-cpu-thermal.dtsi.
> > > >
> > > > For boards who never use industrial temperatures, these can be
> > > > changed on their respective device trees with something like:
> > > >
> > > > &cpu_alert0 {
> > > >       temperature = <85000>; /* millicelsius */
> > > > };
> > > >
> > > > &cpu_crit {
> > > >       temperature = <90000>; /* millicelsius */
> > > > };

I think you should set the lower temperatures by default and have
only the boards known to work with higher values configure them as
needed.

> > > > OMAP3_THERMAL will need to be enabled.  It is off by default.
> > > >  
> > > hmm, I think the patch for idling core when OMAP3_THERMAL is enabled
> > > got stuck somewhere. It still seems not to work. Shouldn't that patch
> > > be applied first?  
> > 
> > I rebased the idle stuff, and now I get errors, so I haven't pushed it
> > yet.  I put a note that OMAP3_THERMAL is off by default, but this
> > patch would at least get the framing in there.  I know at least two of
> > us that use 1GHZ processors which are not supposed to run at that
> > speed above 90MHz, so the idea was to tolerate the higher current for
> > now, and when the idle stuff works, we'll enable the OMAP3_THERMAL by
> > default.
> > 
> yes, makes sense, so with this patch we have the choice to either
> optimize for low speeds and currents (by disabling OMAP3_THERMAL and
> 1GHz) or high speeds (by enabling OMAP3_THERMAL and 1 Ghz).

Maybe add something like that to the patch description too?

Regards,

Tony