linux-kernel - Re: [PATCH 1/3] arm64: dts: rockchip: adjust dcin regulator on ROCK 4D

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Message-ID: <5acizoywvjolaffojiawqlzixiclrqzohuhq55lbsjm6yhhlwi@w2amqugl3ee2>
Date: Tue, 1 Jul 2025 01:10:19 +0200
From: Sebastian Reichel <sebastian.reichel@...labora.com>
To: Diederik de Haas <didi.debian@...ow.org>
Cc: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Heiko Stuebner <heiko@...ech.de>, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org, kernel@...labora.com, 
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/3] arm64: dts: rockchip: adjust dcin regulator on ROCK
 4D

Hi,

On Mon, Jun 30, 2025 at 08:12:27PM +0200, Diederik de Haas wrote:
> Hi Nicolas,
> 
> On Mon Jun 30, 2025 at 5:36 PM CEST, Nicolas Frattaroli wrote:
> > The ROCK 4D's actual DC input is 5V, and the schematic names it as being
> > 5V as well.
> >
> > Rename the regulator, and change the voltage it claims to be at.
> 
> Shouldn't it have a fixes tag then? Providing 12V where 5V is expected
> sounds problematic ;-)

This is basically "just" documentation, as the DT just describes
a fixed regulator (i.e. nothing software controllable). This just
changes a number in sysfs :)

Note, that the 5V DCIN is a USB-C port, which does not do any PD
negotiation, but has the 5K1 resistors on the CC lines to "request"
5V. If for whatever reason a higher voltage is applied (which does
not happen as long as the power is provided by anything remotely
following the USB specifications) there also is an over-voltage
protection chip. So it's not problematic :)

OTOH adding a Fixes tag does not hurt ;)

-- Sebastian

> > Furthermore, fix vcc_1v1_nldo_s3's vin-supply as coming from
> > vcc_5v0_sys, and not the DCIN, as per the schematic. This makes no
> > functional change; both regulators are always on, and one feeds into the
> > other.
> >
> > Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@...labora.com>
> > ---
> >  arch/arm64/boot/dts/rockchip/rk3576-rock-4d.dts | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3576-rock-4d.dts b/arch/arm64/boot/dts/rockchip/rk3576-rock-4d.dts
> > index 6756403111e704cad42f6674d5ab55eb0306f1e3..352e3df165688219bfedc19734d9eb32c547ec44 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3576-rock-4d.dts
> > +++ b/arch/arm64/boot/dts/rockchip/rk3576-rock-4d.dts
> > @@ -57,13 +57,13 @@ user-led {
> >  		};
> >  	};
> >  
> > -	vcc_12v0_dcin: regulator-vcc-12v0-dcin {
> > +	vcc_5v0_dcin: regulator-vcc-5v0-dcin {
> >  		compatible = "regulator-fixed";
> >  		regulator-always-on;
> >  		regulator-boot-on;
> > -		regulator-min-microvolt = <12000000>;
> > -		regulator-max-microvolt = <12000000>;
> > -		regulator-name = "vcc_12v0_dcin";
> > +		regulator-min-microvolt = <5000000>;
> > +		regulator-max-microvolt = <5000000>;
> > +		regulator-name = "vcc_5v0_dcin";
> >  	};
> 
> With the name change, this block needs to be moved down.
> 
> Cheers,
>   Diederik
> >  
> >  	vcc_1v1_nldo_s3: regulator-vcc-1v1-nldo-s3 {
> > @@ -166,7 +166,7 @@ vcc_5v0_device: regulator-vcc-5v0-device {
> >  		regulator-min-microvolt = <5000000>;
> >  		regulator-max-microvolt = <5000000>;
> >  		regulator-name = "vcc_5v0_device";
> > -		vin-supply = <&vcc_12v0_dcin>;
> > +		vin-supply = <&vcc_5v0_sys>;
> >  	};
> >  
> >  	vcc_5v0_host: regulator-vcc-5v0-host {
> > @@ -190,7 +190,7 @@ vcc_5v0_sys: regulator-vcc-5v0-sys {
> >  		regulator-min-microvolt = <5000000>;
> >  		regulator-max-microvolt = <5000000>;
> >  		regulator-name = "vcc_5v0_sys";
> > -		vin-supply = <&vcc_12v0_dcin>;
> > +		vin-supply = <&vcc_5v0_dcin>;
> >  	};
> >  };
> >  
> 



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