linux-kernel - Re: [PATCH v3 0/7] Add support for Allwinner H6 DVFS

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Date:   Mon, 20 Apr 2020 12:39:27 +0200
From:   Ondřej Jirman <megous@...ous.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Clément Péron <peron.clem@...il.com>,
        Chen-Yu Tsai <wens@...e.org>, Rob Herring <robh+dt@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH v3 0/7] Add support for Allwinner H6 DVFS

Hi Maxime,

On Mon, Apr 20, 2020 at 10:45:47AM +0200, Maxime Ripard wrote:
> Hi,
> 
> On Sun, Apr 19, 2020 at 03:50:04PM +0200, Clément Péron wrote:
> > Now that required drivers are merged we can contibute on DVFS
> > support for Allwinner H6.
> > 
> > This serie is based on Yangtao Li serie[0] and Ondřej Jirman work[1].
> > 
> > Most of the OPP tables are taken from original vendor kernel[2].
> > Plus there are new CPU frequencies at 1.6GHz, 1.7GHz and 1.8GHz.
> > 
> > I wrote a simple script to randomly set a frequency during
> > a random time[3]. This script is quite stressfull and set some high
> > frequency without checking temperature. This can result on behavior
> > that whould not occurs with the real cpufreq framework.
> > As Maxime point out I also tested with cpufreq-ljt-stress-test
> > (found here https://github.com/ssvb/cpuburn-arm).
> > This script doesn't trigger any issue.
> > I also test that that offlining CPU0 and doing DVFS on other CPUs
> > works. As CPU regulator is only set for CPU0.
> > 
> > The GPU devfreq was drop as the regulator is still not properly
> > drive by panfrost driver[4].
> > I will re-introduce it later.
> > 
> > Ondřej Jirman has an Orange Pi 3, Jernej has a PineH64 and a Tanix
> > TX6 boards and I have a Beelink GS1 board so I have enable these
> > boards. But CPU Devfreq is really touchy has it depends on:
> > board design, SoC speed_grade and environement which can affect
> > thermal cooling and have different behavior for different user.
> > 
> > If people can test this serie and give feedback, I will try to
> > introduce this in LibreElec tree, so LE community can test it.
> 
> Applied all of them, thanks!

Please also apply "[PATCH v2 1/7] arm64: dts: allwinner: h6: Add
clock to CPU cores" from the v2 series, otherwise cpufreq will
not work.

I can also send a missing patch adding the trip points, and cpu
as a cooling device, that I linked in my other reply to this patch
series afterwards, if Clément wants.

regards,
	o.

> Maxime