linux-kernel - Re: [PATCH v3 1/5] dt-bindings: mfd: rk806: allow to customize PMIC reset mode

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Message-ID: <20250619-unselfish-gorilla-of-joy-13fb93@kuoka>
Date: Thu, 19 Jun 2025 11:54:15 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Quentin Schulz <foss+kernel@...il.net>
Cc: Lee Jones <lee@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Heiko Stuebner <heiko@...ech.de>, Sebastian Reichel <sebastian.reichel@...labora.com>, 
	Lukasz Czechowski <lukasz.czechowski@...umatec.com>, Daniel Semkowicz <dse@...umatec.com>, 
	Nicolas Frattaroli <nicolas.frattaroli@...labora.com>, devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Quentin Schulz <quentin.schulz@...rry.de>
Subject: Re: [PATCH v3 1/5] dt-bindings: mfd: rk806: allow to customize PMIC
 reset mode

On Wed, Jun 18, 2025 at 12:32:40PM GMT, Quentin Schulz wrote:
> From: Quentin Schulz <quentin.schulz@...rry.de>
> 
> The RK806 PMIC allows to configure its reset/restart behavior whenever
> the PMIC is reset either programmatically or via some external pins
> (e.g. PWRCTRL or RESETB).
> 
> The following modes exist:
>  - 0; restart PMU,
>  - 1; reset all power off reset registers and force state to switch to
>    ACTIVE mode,
>  - 2; same as mode 1 and also pull RESETB pin down for 5ms,
> 
> For example, some hardware may require a full restart (mode 0) in order
> to function properly as regulators are shortly interrupted in this mode.
> 
> This is the case for RK3588 Jaguar and RK3588 Tiger which have a
> companion microcontroller running on an independent power supply and
> monitoring the PMIC power rail to know the state of the main system.
> When it detects a restart, it resets its own IPs exposed to the main
> system as if to simulate its own reset. Failing to perform this fake
> reset of the microcontroller may break things (e.g. watchdog not
> automatically disabled, buzzer still running until manually disabled,
> leftover configuration from previous main system state, etc...).

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>

Best regards,
Krzysztof