linux-kernel - Re: [PATCH v2 2/2] regulator: fixed: add support for under-voltage IRQ

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Message-ID: <20231024140634.GD3803936@pengutronix.de>
Date:   Tue, 24 Oct 2023 16:06:34 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Mark Brown <broonie@...nel.org>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/2] regulator: fixed: add support for under-voltage
 IRQ

On Tue, Oct 24, 2023 at 02:26:24PM +0100, Mark Brown wrote:
> On Tue, Oct 24, 2023 at 03:08:42PM +0200, Oleksij Rempel wrote:
> 
> > Add interrupt support for under-voltage notification. This functionality
> > can be used on systems capable to detect under-voltage state and having
> > enough capacity to let the SoC do some emergency preparation.
> > 
> > This change enforce default policy to shutdown system as soon as
> > interrupt is triggered.
> 
> ...
> 
> > +static irqreturn_t reg_fixed_under_voltage_irq_handler(int irq, void *data)
> > +{
> > +	hw_protection_shutdown("Critical voltage drop reached",
> > +			       FV_DEF_EMERG_SHUTDWN_TMO);
> > +
> > +	return IRQ_HANDLED;
> > +}
> 
> We need a bit more policy here - the regulator could be critical to
> system function but it could also be well isolated and just affecting
> whatever device it's directly supplying in a way that the system can
> tolerate and might even want to (eg, for something like a SD card or USB
> port where end users are plugging in external hardware).

Hm, how about devicetree property to indicate system critical nature of
the regulator. For example "system-critical-regulator" or
"system-critical-undervoltage-interrupt" ?

Regards,
Oleksij
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