Re: [linux-sunxi] [PATCH 10/10] ARM: dts: sun8i: Add SY8106A regulator to Orange Pi PC

[icenowy]

å 2017-07-26 15:30ïChen-Yu Tsai åéï
> On Wed, Jul 26, 2017 at 3:16 PM, Icenowy Zheng <icenowy@xxxxxxx> wrote:
> > ä 2017å7æ26æ GMT+08:00 äå3:08:06, Chen-Yu Tsai <wens@xxxxxxxx> åå:
> > > On Sun, Jul 23, 2017 at 6:27 PM, Icenowy Zheng <icenowy@xxxxxxx> 
> > > wrote:
> > > > From: Ondrej Jirman <megous@xxxxxxxxxx>
> > > >
> > > > Add SY8106A regulator to r_i2c bus and enable the r_i2c bus on
> > > > Orange Pi PC, then set the power supply of the ARM cores to this
> > > > regulator, in order to enable DVFS.
> > > >
> > > > Signed-off-by: Ondrej Jirman <megous@xxxxxxxxxx>
> > > > [Icenowy: Enable DVFS in this patch, slight changes and change 
> > > > commit
> > > >  message]
> > > > Signed-off-by: Icenowy Zheng <icenowy@xxxxxxx>
> > > > ---
> > > >  arch/arm/boot/dts/sun8i-h3-orangepi-pc.dts | 19 +++++++++++++++++++
> > > >  1 file changed, 19 insertions(+)
> > > >
> > > > diff --git a/arch/arm/boot/dts/sun8i-h3-orangepi-pc.dts
> > > b/arch/arm/boot/dts/sun8i-h3-orangepi-pc.dts
> > > > index 998b60f8d295..d855f8b6254e 100644
> > > > --- a/arch/arm/boot/dts/sun8i-h3-orangepi-pc.dts
> > > > +++ b/arch/arm/boot/dts/sun8i-h3-orangepi-pc.dts
> > > > @@ -98,6 +98,10 @@
> > > >         status = "okay";
> > > >  };
> > > >
> > > > +&cpu0 {
> > > > +       cpu-supply = <&reg_sy8106a>;
> > > > +};
> > > > +
> > > >  &ehci0 {
> > > >         status = "okay";
> > > >  };
> > > > @@ -160,6 +164,21 @@
> > > >         };
> > > >  };
> > > >
> > > > +&r_i2c {
> > > > +       status = "okay";
> > > > +
> > > > +       reg_sy8106a: regulator@65 {
> > > > +               compatible = "silergy,sy8106a";
> > > > +               reg = <0x65>;
> > > > +               regulator-name = "vdd-cpux";
> > > > +               regulator-min-microvolt = <1000000>;
> > >
> > > According to the H3 datasheet, the minimum voltage is 1.1V, not 1V.
> >
> > But the Armbian OPP table for H3 contains several
> > OPP under 1.1V...
>
> Can you provide a link?
>
> If Armbian users have actually field tested this (a big if),
> then I would like to see some evidence of the SoC running
> stably at those OPPs with those lower voltages under full load.

See [1].

[1] 
https://github.com/armbian/build/blob/master/config/fex/orangepipc.fex#L736

> Even then you should still leave a note describing why we allow
> voltages below the recommended range.
>
> ChenYu
>
> > > Otherwse
> > >
> > > > +               regulator-max-microvolt = <1400000>;
> > > > +               regulator-ramp-delay = <200>;
> > >
> > > Is this an actual constraint of the SoC? Or is it a characteristic
> > > of the regulator? If it is the latter, it belongs in the driver.
> > > AFAIK the regulator supports varying the ramp delay (slew rate).

I don't know...

Maybe I should ask Ondrej?

> > > ChenYu
> > >
> > > > +               regulator-boot-on;
> > > > +               regulator-always-on;
> > > > +       };
> > > > +};
> > > > +
> > > >  &r_pio {
> > > >         leds_r_opc: led_pins@0 {
> > > >                 pins = "PL10";
> > > > --
> > > > 2.13.0