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

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Date:   Thu, 14 Feb 2019 15:35:55 +0100
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Frank Lee <tiny.windzz@...il.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

Hi,

On Thu, Feb 14, 2019 at 10:07:02PM +0800, Frank Lee wrote:
> On Thu, Feb 14, 2019 at 9:46 PM Maxime Ripard <maxime.ripard@...tlin.com> wrote:
> > 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.

Ok, that should definitely be part of the commit log then :)

Thanks!
Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com