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Date: Sat, 20 Jan 2024 00:19:09 +0100
From: Sebastian Reichel <sebastian.reichel@collabora.com>
To: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: Rob Herring <robh+dt@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	Srinivas Kandagatla <srinivas.kandagatla@linaro.org>, kernel@pengutronix.de, linux-kernel@vger.kernel.org, 
	Liam Girdwood <lgirdwood@gmail.com>, Mark Brown <broonie@kernel.org>, 
	"Rafael J. Wysocki" <rafael@kernel.org>, Daniel Lezcano <daniel.lezcano@linaro.org>, 
	Zhang Rui <rui.zhang@intel.com>, Lukasz Luba <lukasz.luba@arm.com>, linux-pm@vger.kernel.org, 
	devicetree@vger.kernel.org, =?utf-8?B?U8O4cmVu?= Andersen <san@skov.dk>
Subject: Re: [RFC PATCH v1 0/7] Introduction of PSCR Framework and Related
 Components
Message-ID: <7gadkjffeljjwb2cgcmg6ixco3xtg4t4hrxtetfnjyzuxvfsjt@ze7u4glqnerb>
References: <20240119132521.3609945-1-o.rempel@pengutronix.de>
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Hi,

On Fri, Jan 19, 2024 at 02:25:14PM +0100, Oleksij Rempel wrote:
> This patch series introduces the Power State Change Reasons (PSCR)
> tracking framework and its related components into the kernel. The PSCR
> framework is designed for systems where traditional methods of storing
> power state change reasons, like PMICs or watchdogs, are inadequate. It
> provides a structured way to store reasons for system shutdowns and
> reboots, such as under-voltage or software-triggered events, in
> non-volatile hardware storage.
>=20
> These changes are critical for systems requiring detailed postmortem
> analysis and where immediate power-down scenarios limit traditional
> storage options. The framework also assists bootloaders and early-stage
> system components in making informed recovery decisions.

A couple of things come to my mind:

1. Do we need the DT based reason-string-to-integer mapping? Can we
   just use a fixed mapping instead? It simplifies the binding a
   lot. With that the generic part could be dropped completely.

2. I would expect the infrastructure to read and clear the reason
   during boot. If e.g. a watchdog triggers a reset you will otherwise
   get an incorrect value.

3. The reason is only stored, but not used? We have a sysfs ABI to
   expose the reboot reason to userspace since half a year ago, see
   d40befed9a58 (power: reset: at91-reset: add sysfs interface to
   the power on reason).

4. Available options should be synced with the list in
   include/linux/power/power_on_reason.h

-- Sebastian

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