linux-kernel - Re: [PATCH] arm64: dts: meson: remove CPU opps below 1GHz for G12B/SM1

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Date:   Wed, 09 Feb 2022 17:31:11 -0800
From:   Kevin Hilman <khilman@...libre.com>
To:     Christian Hewitt <christianshewitt@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Neil Armstrong <narmstrong@...libre.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Christian Hewitt <christianshewitt@...il.com>
Subject: Re: [PATCH] arm64: dts: meson: remove CPU opps below 1GHz for G12B/SM1

Christian Hewitt <christianshewitt@...il.com> writes:

> Amlogic G12B and SM1 devices experience CPU stalls and random board
> wedges when the system idles and CPU cores clock down to lower opp
> points. Recent vendor kernels include a change to remove 100-250MHz
> (with no explanation) [0] but other downstream sources also remove
> the 500/667MHz points (also with no explanation). Unless 100-667Mhz
> opps are removed or the CPU governor forced to performance, stalls
> are observed, so let's remove them an improve stability/uptime.

Just curious: what CPUfreq governor do you use by default for the
LibreELEC kernel?

Your patch greatly improves the stability I'm seeing, but doesn't quite
elimitate it.

I'm testing suspend/resume in a loop on VIM3, and with schedutil
(default) or ondemand, it eventually hangs.  With either powersave or
performance it's stable.  

Kevin