linux-kernel - Re: [PATCH 09/13] arm64: dts: imx95-19x19-evk: Add Tsettle delay in m2 regulator

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Message-ID: <aJ9i3eKARrVZwI0v@lizhi-Precision-Tower-5810>
Date: Fri, 15 Aug 2025 12:39:57 -0400
From: Frank Li <Frank.li@....com>
To: Peng Fan <peng.fan@....com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, devicetree@...r.kernel.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, Richard Zhu <hongxing.zhu@....com>
Subject: Re: [PATCH 09/13] arm64: dts: imx95-19x19-evk: Add Tsettle delay in
 m2 regulator

On Fri, Aug 15, 2025 at 05:03:55PM +0800, Peng Fan wrote:
> From: Richard Zhu <hongxing.zhu@....com>
>
> M.2 device only can be enabled after all Power Rails reach their minimum
> operating voltage (PCI Express M.2 Specification r5.1 3.1.4 Power-up
> Timing). Set a delay equal to the max value of Tsettle in m2 regulator.
>
> Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> Signed-off-by: Peng Fan <peng.fan@....com>

Reviewed-by: Frank Li <Frank.Li@....com>

> ---
>  arch/arm64/boot/dts/freescale/imx95-19x19-evk.dts | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/freescale/imx95-19x19-evk.dts b/arch/arm64/boot/dts/freescale/imx95-19x19-evk.dts
> index feee6da65d37cae7413b09216014d6fe2b76b032..82e183dc581012a7c5be3d2bf749463d0a8a360d 100644
> --- a/arch/arm64/boot/dts/freescale/imx95-19x19-evk.dts
> +++ b/arch/arm64/boot/dts/freescale/imx95-19x19-evk.dts
> @@ -136,6 +136,13 @@ reg_m2_pwr: regulator-m2-pwr {
>  		regulator-max-microvolt = <3300000>;
>  		gpio = <&i2c7_pcal6524 20 GPIO_ACTIVE_HIGH>;
>  		enable-active-high;
> +		/*
> +		 * M.2 device only can be enabled(W_DISABLE1#) after all Power
> +		 * Rails reach their minimum operating voltage (PCI Express M.2
> +		 * Specification r5.1 3.1.4 Power-up Timing).
> +		 * Set a delay equal to the max value of Tsettle here.
> +		 */
> +		startup-delay-us = <5000>;
>  	};
>
>  	reg_pcie0: regulator-pcie {
>
> --
> 2.37.1
>