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Date:   Tue, 09 Feb 2021 18:07:41 -0800
From:   nnet <nnet@fastmail.fm>
To:     =?UTF-8?Q?Marek_Beh=C3=BAn?= <kabel@kernel.org>
Cc:     =?UTF-8?Q?Pali_Roh=C3=A1r?= <pali@kernel.org>, a.heider@gmail.com,
        andrew@lunn.ch, gerald@gk2.net, gregory.clement@bootlin.com,
        kostap@marvell.com, linux-arm-kernel@lists.infradead.org,
        linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org,
        luka.perkov@sartura.hr, miquel.raynal@bootlin.com,
        mturquette@baylibre.com, rmk+kernel@armlinux.org.uk,
        sboyd@kernel.org, tmn505@gmail.com, vladimir.vid@sartura.hr
Subject: =?UTF-8?Q?Re:_[PATCH_mvebu_v2_00/10]_Armada_37xx:_Fix_cpufreq_changing_b?=
 =?UTF-8?Q?ase_CPU_speed_to_800_MHz_from_1000_MHz?=
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On Tue, Feb 9, 2021, at 5:51 PM, nnet 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:
> > > 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 =
heat sinks).
> > > >=20
> > > > The second one ran under load for awhile and now has frozen as w=
ell.
> > > >=20
> > > > Under a moderate load `wget -O /dev/null <large.bin>` @X00Mbits =
they are fine.
> > > >=20
> > > > Under a 1 min speed test of load ~200Mbits routed WireGuard they=
 freeze.
> > > >=20
> > > > They fine with both those workloads @1000_800.
> > > >=20
> > > > Perhaps it's heat? Unfortunately I don't have any numbers on tha=
t ATM.
> > >=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
> > cat /sys/devices/system/cpu/cpufreq/policy0/scaling_available_freque=
ncies=20
> > 200000 300000 600000 1200000=20
> >=20
> > I'm not getting any freezes with 1.2GHz fixed after 20 minutes of lo=
ad:
> >=20
> > echo 1200000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_min_f=
req
> >=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_fr=
eq
> >=20
> > > Marek
> > >
>=20
> > +#define MIN_VOLT_MV_FOR_L0_L1_1GHZ 1108
>=20
> Based on the below at boot time might an equivalent of the above need=20=

> 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

I did this for a quick test for 1.2GHz:

+#define MIN_VOLT_MV_FOR_L0_L1_1GHZ 1225

This is working well so far. Frequency is shifting up/down with load app=
lied/stopped.