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Message-ID: <20250730-giga-cricket-of-development-f886fb@kuoka>
Date: Wed, 30 Jul 2025 09:50:49 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: ChiYuan Huang <cy_huang@...htek.com>
Cc: Sebastian Reichel <sre@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] dt-bindings: power: supply: Add Richtek RT9756 smart
 cap divider charger

On Wed, Jul 30, 2025 at 09:39:38AM +0200, Krzysztof Kozlowski wrote:
> On Wed, Jul 30, 2025 at 10:07:16AM +0800, ChiYuan Huang wrote:
> > On Tue, Jul 29, 2025 at 05:40:32PM +0200, Krzysztof Kozlowski wrote:
> > > On 29/07/2025 06:21, cy_huang@...htek.com wrote:
> > > > +
> > > > +  shunt-resistor-micro-ohms:
> > > > +    description: Battery current sense resistor mounted.
> > > > +    default: 2000
> > > > +
> > > > +required:
> > > > +  - compatible
> > > > +  - reg
> > > > +  - wakeup-source
> > > 
> > > Why do you require this? I cannot find any use of it, so maybe I missed
> > > some change in Linux code (and that's second question like that for
> > > Richtek, so refer to your other patchsets for contexr).
> > > 
> > 
> > This will mark the interrupt as wakeup capable.
> > https://elixir.bootlin.com/linux/v6.16/source/drivers/i2c/i2c-core-of.c#L57
> > https://elixir.bootlin.com/linux/v6.16/source/drivers/i2c/i2c-core-base.c#L547
> 
> OK, but this does not explain why this is required. Why it is impossible
> to make board which uses this PMIC and wires the interrupt in a way it
> is not waking up the system?
> 
> To my limited knowledge this should be possible, but what do I know
> about hardware...

Another question is still valid, although you provided more context - if
the device is ALWAYS waking up, this is implied by compatible and you do
not need this property at all.

That would be the first usage of I2C client wakeup flag in drivers, but
maybe that is how it should be done? You can consult I2C folks on IRC.

Best regards,
Krzysztof


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