Re: [PATCH v3 2/2] ARM: dts: sun8i-r40: Add "cpu-supply" node for sun8i-r40 based board

[qianfan]

在 2022/5/13 15:38, Maxime Ripard 写道:
> Hi,
>
> On Thu, May 12, 2022 at 03:18:58PM +0800, qianfanguijin@xxxxxxx wrote:
> > From: qianfan Zhao <qianfanguijin@xxxxxxx>
> >
> > sun8i-r40 actived cpufreq feature now, let's add "cpu-supply" node on
> > board.
> >
> > Signed-off-by: qianfan Zhao <qianfanguijin@xxxxxxx>
> > ---
> >   arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dts | 4 ++++
> >   arch/arm/boot/dts/sun8i-r40-feta40i.dtsi          | 4 ++++
> >   arch/arm/boot/dts/sun8i-t3-cqa3t-bv3.dts          | 4 ++++
> >   arch/arm/boot/dts/sun8i-v40-bananapi-m2-berry.dts | 4 ++++
> >   4 files changed, 16 insertions(+)
> >
> > diff --git a/arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dts b/arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dts
> > index a6a1087a0c9b..4f30018ec4a2 100644
> > --- a/arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dts
> > +++ b/arch/arm/boot/dts/sun8i-r40-bananapi-m2-ultra.dts
> > @@ -113,6 +113,10 @@ &ahci {
> >   	status = "okay";
> >   };
> >   
> > +&cpu0 {
> > +	cpu-supply = <&reg_dcdc2>;
> > +};
> > +
> This will break bisection on those boards. Indeed, you added the OPPs on
> the first patch, and if you only apply that patch, the boards in the
> second patch will be missing their CPU regulator. The kernel will then
> ramp up the frequency to the highest OPP, but will not change the
> voltage, resulting in a crash.
This is a good point and I will merge those two patch.
> There's a similar issue for all the boards that don't have a regulator
> in the first place.
>
> The way we worked around this for the other SoCs is to have a DTSI with
> the OPPs with a frequency higher than what U-Boot boots with (1008MHz?),
> and only include that DTSI on boards that have a CPU regulator hooked in.
Is this really necessary? It seems like every board based on sun8i-r40
have a cpu regulator.
> Maxime