linux-kernel - Re: [PATCH 1/2] dt-bindings: wkup-m3-ipc: Add vtt toggle bindings

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Message-ID: <YlHubYmrx2w/s20N@x1>
Date:   Sat, 9 Apr 2022 13:37:01 -0700
From:   Drew Fustini <dfustini@...libre.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Nishanth Menon <nm@...com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Dave Gerlach <d-gerlach@...com>,
        Tony Lindgren <tony@...mide.com>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: wkup-m3-ipc: Add vtt toggle bindings

On Sat, Apr 09, 2022 at 06:25:24PM +0200, Krzysztof Kozlowski wrote:
> On 09/04/2022 06:51, Drew Fustini wrote:
> > Document the Wakeup M3 IPC properties that can be used to toggle the VTT
> > regulator during low power mode transitions.
> >
> 
> (...)
> 
> > @@ -51,6 +61,15 @@ properties:
> >        mbox_wkupm3 child node.
> >      maxItems: 1
> >  
> > +  ti,needs-vtt-toggle:
> > +    type: boolean
> > +    description: boards requires VTT toggling during suspend/resume
> > +
> > +  ti,vtt-gpio-pin:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: pin on the GPIO0 module used for VTT toggle
> > +    maxItems: 1
> 
> No need for maxItems, it's a single uint32. You could add "maximum" if
> you know the constraints for the value.

Thank you for letting me know.

> Do you actually need two properties (bool + pin)? A case of
> "ti,vtt-gpio-pin" without the "ti,needs-vtt-toggle" is valid?

You raise a good point. In fact, the driver does nothing useful in the
case of "ti,needs-vtt-toggle" without "ti,vtt-gpio-pin". Therefore, I
will remove the "ti,needs-vtt-toggle" property.

> 
> The other way looks wrong, so you need to add a dependency (see
> example-schema).
> 
> 
> Best regards,
> Krzysztof

Thank you,
Drew