linux-kernel - Re: [PATCH 1/9] arm64: dts: imx8mn-bsh-smm-s2-common: Define suspend voltage threshold

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Message-ID: <057c6bc2-adf9-4160-9184-6438cbe6e9d4@gmail.com>
Date: Thu, 15 May 2025 11:52:45 +0300
From: Matti Vaittinen <mazziesaccount@...il.com>
To: Dario Binacchi <dario.binacchi@...rulasolutions.com>,
 linux-kernel@...r.kernel.org
Cc: Simon Holesch <simon.holesch@...g.com>,
 Karthikdatt Anantharamrao <karthikdatt.anantharamrao@...bosch.com>,
 michael@...rulasolutions.com, linux-amarula@...rulasolutions.com,
 Wolfgang Birkner <wolfgang.birkner@...g.com>,
 Conor Dooley <conor+dt@...nel.org>, Fabio Estevam <festevam@...il.com>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Pengutronix Kernel Team <kernel@...gutronix.de>,
 Rob Herring <robh@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Shawn Guo <shawnguo@...nel.org>, devicetree@...r.kernel.org,
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/9] arm64: dts: imx8mn-bsh-smm-s2-common: Define suspend
 voltage threshold

On 14/05/2025 11:24, Dario Binacchi wrote:
> From: Michael Trimarchi <michael@...rulasolutions.com>
> 
> Voltage threshold should be adjust according to the worst case.

I would love to understand why these voltages are set.

Could you please explain a bit further why this change is done. What 
worst case? What happens if voltages aren't adjusted? What is the 
current voltage (before this patch is applied?).

> Signed-off-by: Michael Trimarchi <michael@...rulasolutions.com>
> Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>
> ---
> 
>   .../boot/dts/freescale/imx8mn-bsh-smm-s2-common.dtsi  | 11 +++++++++++
>   1 file changed, 11 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mn-bsh-smm-s2-common.dtsi b/arch/arm64/boot/dts/freescale/imx8mn-bsh-smm-s2-common.dtsi
> index bbb07c650da9..5a1ec2f6a552 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mn-bsh-smm-s2-common.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mn-bsh-smm-s2-common.dtsi
> @@ -105,6 +105,12 @@ buck1_reg: BUCK1 {
>   				regulator-boot-on;
>   				regulator-always-on;
>   				regulator-ramp-delay = <1250>;
> +
> +				/* enable autosuspend threshold */
> +				rohm,dvs-run-voltage = <850000>;
> +				rohm,dvs-idle-voltage = <850000>;
> +				rohm,dvs-suspend-voltage = <850000>;
> +				rohm,no-regulator-enable-control;

The commit message does not explain why the software control of the 
regulator's enable state is changed? Maybe this should be in the 2/9?

>   			};
>   
>   			buck2_reg: BUCK2 {
> @@ -115,6 +121,11 @@ buck2_reg: BUCK2 {
>   				regulator-boot-on;
>   				regulator-always-on;
>   				regulator-ramp-delay = <1250>;
> +
> +				/* enable autosuspend threshold */
> +				rohm,dvs-run-voltage = <960000>;
> +				rohm,dvs-idle-voltage = <860000>;
> +				rohm,no-regulator-enable-control;

same here?

>   			};
>   
>   			buck3_reg: BUCK3 {

Yours,
	-- Matti