linux-kernel - Re: [PATCH] arm64: dts: rockchip: fix nEXTRST on SOQuartz

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Date:   Fri, 21 Apr 2023 14:38:48 +0200
From:   Nicolas Frattaroli <frattaroli.nicolas@...il.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Peter Geis <pgwipeout@...il.com>,
        Heiko Stuebner <heiko@...ech.de>
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: rockchip: fix nEXTRST on SOQuartz

Hello,

On Friday, 21 April 2023 13:58:58 CEST Heiko Stuebner wrote:
> Hi,
> 
> Am Mittwoch, 19. April 2023, 19:17:31 CEST schrieb Nicolas Frattaroli:
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3566-soquartz.dtsi
> > b/arch/arm64/boot/dts/rockchip/rk3566-soquartz.dtsi index
> > ce7165d7f1a1..f589a4fdaccb 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3566-soquartz.dtsi
> > +++ b/arch/arm64/boot/dts/rockchip/rk3566-soquartz.dtsi
> > @@ -65,6 +65,17 @@ led_work: led-work {
> > 
> >  		};
> >  	
> >  	};
> > 
> > +	nextrst_pin: nextrst-pin-regulator {
> > +		compatible = "regulator-fixed";
> > +		enable-active-high;
> > +		gpio = <&gpio0 RK_PA5 GPIO_ACTIVE_HIGH>;
> > +		pinctrl-names = "default";
> > +		pinctrl-0 = <&nextrst_h>;
> > +		regulator-always-on;
> > +		regulator-boot-on;
> > +		regulator-name = "nextrst";
> > +	};
> > +
> 
> I agree with the sentiment and of course the rationale of the change,
> but not necessarily with the implementation ;-) .
> 
> Why is this done as a regulator?
> 
> If you want the nextrst line to be high, you could just use a gpio-hog
> for the line instead of doing a (fake?-)regulator.

Simply put: because I didn't know gpio hogs were a thing. I'll send a V2
to correct this. Thanks for pointing it out!

> 
> For example the px30-ringneck.dtsi does something similar:
> 
> &gpio2 {
>         /*
>          * The Qseven BIOS_DISABLE signal on the PX30-µQ7 keeps the
> on-module * eMMC powered-down initially (in fact it keeps the reset signal
> * asserted). BIOS_DISABLE_OVERRIDE pin allows to re-enable eMMC after * the
> SPL has been booted from SD Card.
>          */
>         bios-disable-override-hog {
>                 gpios = <RK_PB5 GPIO_ACTIVE_LOW>;
>                 output-high;
>                 line-name = "bios_disable_override";
>                 gpio-hog;
>         };
> ...
> };
> 
> 
> Thanks
> Heiko

Kind regards,
Nicolas Frattaroli