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From:   =?UTF-8?B?Q2zDqW1lbnQgUMOpcm9u?= <peron.clem@gmail.com>
Date:   Mon, 4 May 2020 21:34:17 +0200
Message-ID: <CAJiuCcdSmgp75ByEDDtH0AtqGsUyc9QrAcD9xqLZduh2ijnrqQ@mail.gmail.com>
Subject: Re: [linux-sunxi] [PATCH v2] arm64: dts: allwinner: h6: Use dummy
 regulator for Tanix TX6
To:     =?UTF-8?Q?Ond=C5=99ej_Jirman?= <megous@megous.com>,
        =?UTF-8?B?Q2zDqW1lbnQgUMOpcm9u?= <peron.clem@gmail.com>,
        Maxime Ripard <mripard@kernel.org>,
        Chen-Yu Tsai <wens@csie.org>, Rob Herring <robh+dt@kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        devicetree <devicetree@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-sunxi <linux-sunxi@googlegroups.com>,
        Piotr Oniszczuk <warpme@o2.pl>
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Hi Ondrej,

On Mon, 4 May 2020 at 14:27, Ond=C5=99ej Jirman <megous@megous.com> wrote:
>
> Hi Cl=C3=A9ment,
>

<snip>

>
> So I guess ignoring the voltage and not disabling this OPP may or may not=
 work
> based on SoC bin.
>
> On Orange Pi One, there's a regulator that supports two voltages (that ca=
n't
> support all the listed OPPs for H3), and cpufreq-dt can deal with that
> automagically, if you specify OPP voltages via a tripplet of [prefered mi=
n max].
> Kernell will log this in dmesg on boot:
>
> [    0.672440] core: _opp_supported_by_regulators: OPP minuV: 1320000 max=
uV: 1320000, not supported by regulator
> [    0.672454] cpu cpu0: _opp_add: OPP not supported by regulators (11040=
00000)
> [    0.672523] core: _opp_supported_by_regulators: OPP minuV: 1320000 max=
uV: 1320000, not supported by regulator
> [    0.672530] cpu cpu0: _opp_add: OPP not supported by regulators (12000=
00000)
> [    0.672621] core: _opp_supported_by_regulators: OPP minuV: 1340000 max=
uV: 1340000, not supported by regulator
> [    0.672628] cpu cpu0: _opp_add: OPP not supported by regulators (12960=
00000)
> [    0.672712] core: _opp_supported_by_regulators: OPP minuV: 1400000 max=
uV: 1400000, not supported by regulator
> [    0.672719] cpu cpu0: _opp_add: OPP not supported by regulators (13680=
00000)
>
> And the list of available OPPs will be reduced at runtime to a supportabl=
e
> set by the CPU regulator.
>
> If you look at:
>
>   https://megous.com/git/linux/commit/?h=3Dths-5.7&id=3Dd231770195913cf54=
3c0cf9539deee2ecec06680
>
> you'll see a bunch of OPPs for H3 that are specified as a range. So
> for example if you want 480MHz, and your regulator can't produce
> 1.04V exactly, cpufreq will set the voltage to something supportable
> in the range.
>
> I think the proper fix is to fix the OPP table for H6, so that it uses
> voltage ranges for each OPP and not a single fixed voltage, to support
> boards that don't have the standard PMIC that goes with H6.

Thanks for the suggestion and I agree with you, this is a good way to
keep the same OPP table for all the H6 devices and handle both board
with PMIC and with fixed regulator.

I will propose a patch.

Thanks clement

>
> regards,
>         o.