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

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Date:   Fri, 21 Apr 2023 13:58:58 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Frattaroli <frattaroli.nicolas@...il.com>
Cc:     Nicolas Frattaroli <frattaroli.nicolas@...il.com>,
        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

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.

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