linux-kernel - Re: [PATCH 1/4] arm64: dts: allwinner: h6: orangepi: Add CPU supply regulator

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Message-ID: <CAEExFWvG4Vz2KsDnHJ6BL72nD6x=Lp+Hzj+q7LfggzFtzrgRow@mail.gmail.com>
Date:   Thu, 14 Feb 2019 22:07:02 +0800
From:   Frank Lee <tiny.windzz@...il.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     Chen-Yu Tsai <wens@...e.org>, robh+dt@...nel.org,
        mark.rutland@....com,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        devicetree@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/4] arm64: dts: allwinner: h6: orangepi: Add CPU supply regulator

On Thu, Feb 14, 2019 at 9:46 PM Maxime Ripard <maxime.ripard@...tlin.com> wrote:
>
> Hi!
>
> Thanks for your patches
>
> On Thu, Feb 14, 2019 at 08:09:07AM -0500, Yangtao Li wrote:
> > The original orangepi use the dcdca to supply the CPU cores. According
> > to the axp805 spec, the range of dcdca is 0.6 to 1.1v, 1.12 to 1.52v.
> > In order to support more CPU frequency, slightly increase the voltage
> > maximum and minimum.
> >
> > Signed-off-by: Yangtao Li <tiny.windzz@...il.com>
> > ---
> >  arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi.dtsi | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi.dtsi b/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi.dtsi
> > index b2526dac2fcf..e7aebaf91ede 100644
> > --- a/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi.dtsi
> > +++ b/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi.dtsi
> > @@ -159,8 +159,8 @@
> >
> >                       reg_dcdca: dcdca {
> >                               regulator-always-on;
> > -                             regulator-min-microvolt = <810000>;
> > -                             regulator-max-microvolt = <1080000>;
> > +                             regulator-min-microvolt = <800000>;
> > +                             regulator-max-microvolt = <1160000>;
>
> This violates the minimum and maximum recommended voltages in the H6
> datasheet. Could you clarify why you are doing so (ideally in the
> commit log)?
In fact, in sunxi's sdk, the actual minimum and maximum voltage of the
cpu is smaller or larger than the datasheet.

For some better quality ic, the minimum voltage can be smaller.
For some poor quality ic, the maximum voltage needs to be increased a little.

MBR,
Yangtao
>
> Thanks!
> Maxime
>
> --
> Maxime Ripard, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com