Re: [PATCH 6/8] ARM: dts: mstar: miyoo-mini: Add vbat switch

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Missing `regulator-boot-on` will cause a power glitch if the rail is already on, or `regulator-always-on` will drain battery if it's an ADC switch.
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--- Patch [6]: [PATCH 6/8] ARM: dts: mstar: miyoo-mini: Add vbat switch ---
commit a658b11235430fff38550ae571d1b7afe1a12775
Author: Daniel Palmer <daniel@0x0f.com>

ARM: dts: mstar: miyoo-mini: Add vbat switch

This commit adds a GPIO-controlled fixed regulator for the battery voltage
rail on the Miyoo Mini device.

> diff --git a/arch/arm/boot/dts/sigmastar/mstar-infinity2m-ssd202d-miyoo-mini.dts b/arch/arm/boot/dts/sigmastar/mstar-infinity2m-ssd202d-miyoo-mini.dts
> index 5e927f41fa733..fde4703eb52bc 100644
> --- a/arch/arm/boot/dts/sigmastar/mstar-infinity2m-ssd202d-miyoo-mini.dts
> +++ b/arch/arm/boot/dts/sigmastar/mstar-infinity2m-ssd202d-miyoo-mini.dts
[ ... ]
> @@ -24,6 +26,15 @@ vibrator {
>  		enable-gpios = <&gpio SSD20XD_GPIO_UART0_TX GPIO_ACTIVE_LOW>;
>  	};
>  
> +	reg_vbat: regulator-vbat {
> +		compatible = "regulator-fixed";
> +		regulator-name = "vbat";
> +		regulator-min-microvolt = <4200000>;
> +		regulator-max-microvolt = <4200000>;
> +		gpio = <&gpio SSD20XD_GPIO_GPIO85 GPIO_ACTIVE_HIGH>;
> +		enable-active-high;
> +		regulator-always-on;

[Severity: Medium]
Will this configuration cause a power glitch during probe or an unintended
battery drain?

Because regulator-boot-on is omitted, the fixed regulator driver initializes
the GPIO request as GPIOD_OUT_LOW, instantly dropping the line to 0V. The
regulator core will later process regulator-always-on and re-enable it, but
this gap can cause a power glitch if this rail is a system power hold latch
already enabled by the bootloader.

Alternatively, if this GPIO controls a voltage divider switch for an ADC
reading, leaving it regulator-always-on will cause a continuous battery
drain. 

Should regulator-boot-on be added, or regulator-always-on be removed
depending on the exact hardware function?

> +	};
>  };

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260713105950.1346962-1-daniel@thingy.jp?part=6