linux-kernel - Re: [PATCH v2 3/5] arm64: dts: freescale: add Ka-Ro Electronics tx8m-1610 COM

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Message-ID: <a7012995-c2a8-48a3-abe1-5c227272f21c@gmail.com>
Date: Tue, 28 Oct 2025 14:15:05 +0200
From: Matti Vaittinen <mazziesaccount@...il.com>
To: maudspierings@...ontroll.com, 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>
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 3/5] arm64: dts: freescale: add Ka-Ro Electronics
 tx8m-1610 COM

Hi Maud,

Thanks for the upstreaming work! :)

On 22/10/2025 10:22, Maud Spierings via B4 Relay wrote:
> From: Maud Spierings <maudspierings@...ontroll.com>
> 
> The Ka-Ro Electronics tx8m-1610 is a COM based on the imx8mm SOC. It has
> 1 GB of ram and 4 GB of eMMC storage on board.
> 
> Add it to enable boards based on this module
> 
> Signed-off-by: Maud Spierings <maudspierings@...ontroll.com>
> ---
>   .../arm64/boot/dts/freescale/imx8mm-tx8m-1610.dtsi | 439 +++++++++++++++++++++
>   1 file changed, 439 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mm-tx8m-1610.dtsi b/arch/arm64/boot/dts/freescale/imx8mm-tx8m-1610.dtsi
> new file mode 100644
> index 0000000000000..46d3ad80942cc
> --- /dev/null
> +++ b/arch/arm64/boot/dts/freescale/imx8mm-tx8m-1610.dtsi
> @@ -0,0 +1,439 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> +/*
> + * Copyright (C) 2021 Lothar Waßmann <LW@...O-electronics.de>
> + * 2025 Maud Spierings <maudspierings@...ontroll.com>
> + */
> +
> +#include "imx8mm.dtsi"
> +

// snip

> +	pmic: pmic@4b {
> +		compatible = "rohm,bd71847";
> +		reg = <0x4b>;
> +		interrupt-parent = <&gpio1>;
> +		interrupts = <3 IRQ_TYPE_LEVEL_LOW>;
> +		pinctrl-0 = <&pinctrl_pmic>;
> +		pinctrl-names = "default";
> +		rohm,reset-snvs-powered;
> +
> +		regulators {
> +			reg_vdd_soc: BUCK1 {
> +				regulator-always-on;
> +				regulator-boot-on;
> +				regulator-max-microvolt = <900000>;
> +				regulator-min-microvolt = <780000>;
> +				regulator-name = "buck1";
> +				regulator-ramp-delay = <1250>;
> +			};
> +
> +			reg_vdd_arm: BUCK2 {
> +				regulator-always-on;
> +				regulator-boot-on;
> +				regulator-max-microvolt = <950000>;
> +				regulator-min-microvolt = <805000>;
> +				regulator-name = "buck2";
> +				regulator-ramp-delay = <1250>;
> +				rohm,dvs-run-voltage = <950000>;
> +				rohm,dvs-idle-voltage = <810000>;
> +			};
> +
> +			reg_vdd_dram: BUCK3 {
> +				regulator-always-on;
> +				regulator-boot-on;
> +				regulator-max-microvolt = <900000>;
> +				regulator-min-microvolt = <805000>;
> +				regulator-name = "buck3";
> +			};
> +
> +			reg_vdd_3v3: BUCK4 {
> +				regulator-always-on;
> +				regulator-boot-on;
> +				regulator-max-microvolt = <3300000>;
> +				regulator-min-microvolt = <3300000>;
> +				regulator-name = "buck4";
> +			};
> +
> +			reg_vdd_1v8: BUCK5 {
> +				regulator-always-on;
> +				regulator-boot-on;
> +				regulator-max-microvolt = <1950000>;
> +				regulator-min-microvolt = <1700000>;
> +				regulator-name = "buck5";
> +			};
> +
> +			BUCK6 {
> +				regulator-always-on;
> +				regulator-boot-on;
> +				/*
> +				 * The default output voltage is 1.1V, bumped
> +				 * to 1.35V in HW by a 499R/2.2K voltage divider in the
> +				 * feedback path.
> +				 */

Could/Should this be described using the:
'rohm,feedback-pull-up-r1-ohms' and
'rohm,feedback-pull-up-r2-ohms'? If I understand the comment correctly, 
that might allow the driver to be able to use correctly scaled voltages.

https://elixir.bootlin.com/linux/v6.18-rc1/source/Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.yaml#L108

> +				regulator-max-microvolt = <1100000>;
> +				regulator-min-microvolt = <1100000>;
> +				regulator-name = "buck6";
> +			};

Yours,
	-- Matti