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References: <20240119132521.3609945-1-o.rempel@pengutronix.de>
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From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Fri, 19 Jan 2024 21:11:57 +0100
Message-ID: <CAJZ5v0jvJa-TaB_ifNdDCDMLozAuX=e7ddgUcU1tx_3Rzp3rcA@mail.gmail.com>
Subject: Re: [RFC PATCH v1 7/7] thermal: core: set Power State Change Reason
 before hw_protection_shutdown()
To: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>, devicetree@vger.kernel.org, 
	Conor Dooley <conor+dt@kernel.org>, Daniel Lezcano <daniel.lezcano@linaro.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Liam Girdwood <lgirdwood@gmail.com>, 
	Mark Brown <broonie@kernel.org>, Sebastian Reichel <sre@kernel.org>, linux-kernel@vger.kernel.org, 
	=?UTF-8?Q?S=C3=B8ren_Andersen?= <san@skov.dk>, 
	Rob Herring <robh+dt@kernel.org>, Srinivas Kandagatla <srinivas.kandagatla@linaro.org>, 
	kernel@pengutronix.de, linux-pm@vger.kernel.org, 
	Zhang Rui <rui.zhang@intel.com>, Lukasz Luba <lukasz.luba@arm.com>
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On Fri, Jan 19, 2024 at 8:34=E2=80=AFPM Oleksij Rempel <o.rempel@pengutroni=
x.de> wrote:
>
> On Fri, Jan 19, 2024 at 07:34:26PM +0100, Rafael J. Wysocki wrote:
> > On Fri, Jan 19, 2024 at 2:25=E2=80=AFPM Oleksij Rempel <o.rempel@pengut=
ronix.de> wrote:
> > >
> > > Store the state change reason to some black box for later investigati=
on.
> >
> > Seriously?
> >
> > What black box, where, how this is useful and who is going to use it,
> > pretty please.
>
> The 'black box' refers to a non-volatile memory (NVMEM) cell used by the
> Power State Change Reasons (PSCR) framework. This cell stores reasons
> for sudden power state changes, like voltage drops or over-temperature
> events. This data is invaluable for post-mortem analysis to understand
> system failures or abrupt shutdowns. It's particularly useful for
> systems where PMICs or watchdogs cannot record such events. The data can
> inform recovery routines in the bootloader or early kernel stages during
> subsequent boots, enhancing system reliability and aiding in debugging
> and diagnostics.

OK, so please add all of the above to the patch changelog.