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Date:   Wed, 10 Feb 2021 03:12:37 +0100
From:   Marek =?UTF-8?B?QmVow7pu?= <kabel@kernel.org>
To:     nnet <nnet@fastmail.fm>
Cc:     Pali =?UTF-8?B?Um9ow6Fy?= <pali@kernel.org>, a.heider@gmail.com,
        andrew@lunn.ch, gerald@gk2.net, gregory.clement@bootlin.com,
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        mturquette@baylibre.com, rmk+kernel@armlinux.org.uk,
        sboyd@kernel.org, tmn505@gmail.com, vladimir.vid@sartura.hr
Subject: Re: [PATCH mvebu v2 00/10] Armada 37xx: Fix cpufreq changing base
 CPU speed to 800 MHz from 1000 MHz
Message-ID: <20210210031237.6229b7ef@kernel.org>
In-Reply-To: <1cd0c2ee-aa3a-4da2-9c0c-57cc5a1dad49@www.fastmail.com>
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On Tue, 09 Feb 2021 17:51:53 -0800
nnet <nnet@fastmail.fm> wrote:

> On Tue, Feb 9, 2021, at 5:31 PM, nnet wrote:
> > On Tue, Feb 9, 2021, at 3:26 PM, Marek Beh=C3=BAn wrote: =20
> > > On Tue, 09 Feb 2021 15:16:45 -0800
> > > nnet <nnet@fastmail.fm> wrote:
> > >  =20
> > > > I've two of these and I've just swapped them (and re-pasted the hea=
t sinks).
> > > >=20
> > > > The second one ran under load for awhile and now has frozen as well.
> > > >=20
> > > > Under a moderate load `wget -O /dev/null <large.bin>` @X00Mbits the=
y are fine.
> > > >=20
> > > > Under a 1 min speed test of load ~200Mbits routed WireGuard they fr=
eeze.
> > > >=20
> > > > They fine with both those workloads @1000_800.
> > > >=20
> > > > Perhaps it's heat? Unfortunately I don't have any numbers on that A=
TM. =20
> > >=20
> > > Try disabling cpufreq in kernel completely, compile boot image at
> > > 1200 MHz. If it continues freezing, then I fear we can't help you with
> > > 1200 MHz :( =20
> >=20
> > cat /sys/devices/system/cpu/cpufreq/policy0/scaling_available_frequenci=
es=20
> > 200000 300000 600000 1200000=20
> >=20
> > I'm not getting any freezes with 1.2GHz fixed after 20 minutes of load:
> >=20
> > echo 1200000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_min_freq
> >=20
> > Setting it back to min 200MHz I get a freeze within a minute:
> >=20
> > echo 200000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_min_freq
> >  =20
> > > Marek
> > > =20
>=20
> > +#define MIN_VOLT_MV_FOR_L0_L1_1GHZ 1108 =20
>=20
> Based on the below at boot time might an equivalent of the above need to =
be 1225 for 1.2GHz?
>=20
> 1200_750
> SVC REV: 5, CPU VDD voltage: 1.225V
>=20
> 1000_800
> SVC REV: 5, CPU VDD voltage: 1.108V

It may be... But it is possible that the value 1.225 is computed by the
code by default.

Marek