linux-kernel - Re: [PATCH] arm64: dts: imx8mp-verdin: board regulators: add always-on

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Date:   Thu, 1 Sep 2022 21:29:13 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Max Krummenacher <max.oss.09@...il.com>
Cc:     Max Krummenacher <max.krummenacher@...adex.com>,
        Fabio Estevam <festevam@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        Rob Herring <robh+dt@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH] arm64: dts: imx8mp-verdin: board regulators: add
 always-on

Hi Max,

(CC'ing Mark and Liam)

Thank you for the patch.

On Thu, Sep 01, 2022 at 01:04:22PM +0200, Max Krummenacher wrote:
> From: Max Krummenacher <max.krummenacher@...adex.com>
> 
> These regulators are switched on by HW during power up and can not
> be influenced by SW.
> Set the always-on property.

Is this needed ? When a fixed regulator has no control GPIO or clock, as
is the case here, I would expect the driver and/or regulator core to
understand that it's always on, as the alternative is always-off, which
is pointless :-) Mark, Liam, what do you think ?

> Signed-off-by: Max Krummenacher <max.krummenacher@...adex.com>
> 
> ---
> 
>  arch/arm64/boot/dts/freescale/imx8mp-verdin.dtsi | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mp-verdin.dtsi b/arch/arm64/boot/dts/freescale/imx8mp-verdin.dtsi
> index 557cfef8f049..76cc89296150 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mp-verdin.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mp-verdin.dtsi
> @@ -62,6 +62,7 @@ button-wakeup {
>  	/* Carrier Board Supplies */
>  	reg_1p8v: regulator-1p8v {
>  		compatible = "regulator-fixed";
> +		regulator-always-on;
>  		regulator-max-microvolt = <1800000>;
>  		regulator-min-microvolt = <1800000>;
>  		regulator-name = "+V1.8_SW";
> @@ -69,6 +70,7 @@ reg_1p8v: regulator-1p8v {
>  
>  	reg_3p3v: regulator-3p3v {
>  		compatible = "regulator-fixed";
> +		regulator-always-on;
>  		regulator-max-microvolt = <3300000>;
>  		regulator-min-microvolt = <3300000>;
>  		regulator-name = "+V3.3_SW";
> @@ -76,6 +78,7 @@ reg_3p3v: regulator-3p3v {
>  
>  	reg_5p0v: regulator-5p0v {
>  		compatible = "regulator-fixed";
> +		regulator-always-on;
>  		regulator-max-microvolt = <5000000>;
>  		regulator-min-microvolt = <5000000>;
>  		regulator-name = "+V5_SW";

-- 
Regards,

Laurent Pinchart