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From:   Erwan Velu <erwanaliasr1@gmail.com>
Date:   Wed, 20 Feb 2019 12:24:38 +0100
Message-ID: <CAL2JzuyyFeX6rE3vTASV2gikXp8xB-WtnSo4YazccaxfcE_nQg@mail.gmail.com>
Subject: Re: [PATCH] cpufreq: Report if CPU doesn't report boost technologies
To:     "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     Erwan Velu <e.velu@criteo.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        "open list:CPU FREQUENCY SCALING FRAMEWORK" 
        <linux-pm@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
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I tried to put the message in a way to stay neutral, not saying if its
a real error or not.
Just reporting we were not able to find any boost cap on it.
Erwan,

Le mer. 20 f=C3=A9vr. 2019 =C3=A0 12:16, Rafael J. Wysocki <rafael@kernel.o=
rg> a =C3=A9crit :
>
> On Wed, Feb 20, 2019 at 11:52 AM Erwan Velu <e.velu@criteo.com> wrote:
> >
> >
> > Le 20/02/2019 =C3=A0 11:41, Rafael J. Wysocki a =C3=A9crit :
> > > On Wed, Feb 20, 2019 at 11:11 AM Erwan Velu <erwanaliasr1@gmail.com> =
wrote:
> > >> There is some rare cases where CPB (and possibly IDA) are missing on=
 processors.
> > >> This is the case fixed by commit f7f3dc00f612 ("x86/cpu/AMD: Fix err=
atum 1076 (CPB bit)") and following.
> > >>
> > >> In such context, the boost status isn't reported by /sys/devices/sys=
tem/cpu/cpufreq/boost.
> > > So I'm not really sure why the extra message is needed.  It looks lik=
e
> > > this message will always be printed (with debug output enabled) if th=
e
> > > current cpufreq driver is acpi-cpufreq and the boost attribute is not
> > > present in sysfs, which only is the case if CPB/IDA aren't there.
> > >
> > > Does it provide any additional information, then?
> >
> > When you know and read the code, yes this patch is too obvious.
> >
> > As a user when I was troubleshooting why the boost entry was _not_
> > populated on one CPU and was populated on another.
> >
> > Running acpi-cpufreq with dyndbg, I would have found useful to get that
> > hint.
> >
> > So that could helps users that never read that part of the code and
> > which are tricked into that configuration.
>
> OK, I see your point.
>
> I'll queue up the patch, but I guess I'll change the message.