linux-kernel - Re: [PATCH v6 1/3] dt-bindings: Add beaglecc1352

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Date:   Tue, 3 Oct 2023 08:05:56 -0500
From:   Nishanth Menon <nm@...com>
To:     Ayush Singh <ayushdevel1325@...il.com>
CC:     <greybus-dev@...ts.linaro.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <gregkh@...uxfoundation.org>,
        <vaishnav@...gleboard.org>, <jkridner@...gleboard.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <vigneshr@...com>,
        <kristo@...nel.org>, <robh+dt@...nel.org>, <conor+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v6 1/3] dt-bindings: Add beaglecc1352

On 18:17-20231003, Ayush Singh wrote:
> > > +
> > > +  reset-gpios:
> > > +    maxItems: 1
> > > +
> > > +  power-gpios:
> > > +    maxItems: 3
> > > +    description:
> > > +      The device has three power rails that are exposed on external pins VDDS,
> > > +      VDDR and DCOUPL.
> > Shouldn't these be regulators? The power rails are input to the MCU,
> > correct?
> > The properties should be something like:
> > vdds-supply
> > vddr-supply
> > dcoupl-supply ? (not sure what dcoupl is, but description should provide
> > 		that info).
> > 
> > the gpio controls for those can be modelled by regulator-gpio ?
> 
> I picked up power lines from "CC13xx/CC26xx Hardware Configuration and PCB
> Design Considerations Application Report" present under "8.14 Network
> Processor" of CC1352P7 data sheet.
> 
> But now looking closer, it doesn't seem like DCOUPL can be supplied
> externally for CC1352P7 and thus should probably be removed.
> 
> Also, it seems like for CC1352P7, VDDR must always be supplied internally
> (The data sheet states: "Internal supply, must be powered from the internal
> DC/DC converter or the internal LDO"). Thus, it should be safe to remove
> VDDR as well.
>From Figure 3-1. CC1312R 7x7 RF Part Schematic Overview (app report you
point out below)
Typical usage is vdds-supply supplying:
VDDS (pin 44)
VDDS2 (pin 13)
VDDS3 (pin 22)
VDDS_DCDC (pin 34)

And DCDC_SW (pin 33) supplies vddr supplying:
VDDR(pin 45)
VDDR_RF (Pin 48)

> 
> 
> That means only VDDS needs to be present for power line.

I agree that that would be the typical supply model. So, just
vdds-supply

> 
> 
> CC13xx/CC26xx Hardware Configuration and PCB Design Considerations
> Application Report: https://www.ti.com/lit/pdf/swra640
> 
> CC1352P7 Data sheet: https://www.ti.com/lit/gpn/CC1352P7

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D