linux-kernel - Re: [PATCH 1/6] dt-bindings: regulator: pca9450: Document new usage of sd-vsel-gpios

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Date:   Wed, 15 Feb 2023 20:30:47 -0600
From:   Rob Herring <robh@...nel.org>
To:     Marek Vasut <marex@...x.de>
Cc:     Frieder Schrempf <frieder@...s.de>, devicetree@...r.kernel.org,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>,
        Robin Gong <yibin.gong@....com>,
        Frieder Schrempf <frieder.schrempf@...tron.de>,
        Per-Daniel Olsson <perdo@...s.com>,
        Rickard x Andersson <rickaran@...s.com>
Subject: Re: [PATCH 1/6] dt-bindings: regulator: pca9450: Document new usage
 of sd-vsel-gpios

On Wed, Feb 15, 2023 at 7:27 PM Marek Vasut <marex@...x.de> wrote:
>
> On 2/15/23 21:02, Rob Herring wrote:
> > On Mon, Feb 13, 2023 at 04:58:19PM +0100, Frieder Schrempf wrote:
> >> From: Frieder Schrempf <frieder.schrempf@...tron.de>
> >>
> >> The sd-vsel-gpios property is abandoned in its current meaning as an
> >> output. We now use it to specify an optional signal that can be
> >> evaluated by the driver in order to retrieve the current status
> >> of the SD_VSEL signal that is used to select the control register
> >> of LDO5.
> >>
> >> Signed-off-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> >> ---
> >>   .../regulator/nxp,pca9450-regulator.yaml      | 23 ++++++++++++++-----
> >>   1 file changed, 17 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/regulator/nxp,pca9450-regulator.yaml b/Documentation/devicetree/bindings/regulator/nxp,pca9450-regulator.yaml
> >> index 835b53302db8..c86534538a4e 100644
> >> --- a/Documentation/devicetree/bindings/regulator/nxp,pca9450-regulator.yaml
> >> +++ b/Documentation/devicetree/bindings/regulator/nxp,pca9450-regulator.yaml
> >> @@ -40,8 +40,24 @@ properties:
> >>       description: |
> >>         list of regulators provided by this controller
> >>
> >> +    properties:
> >> +      LDO5:
> >> +        type: object
> >> +        $ref: regulator.yaml#
> >> +        description:
> >> +          Properties for single LDO5 regulator.
> >> +
> >> +        properties:
> >> +          sd-vsel-gpios:
> >
> > It is a pin on the device, right? Then it belongs in the device node as
> > it was.
> >
> > Can't the direction of the signal tell you how it is used? Assuming the
> > pin is bidirectional?
>
> The pin is input to the PMIC, it is unidirection, i.e.
>
> SoC(output)---->(input)PMIC
>
> > The binding should support any possible way the device is wired, not
> > just what's been seen so far on some boards.
>
> The usage is always the above as far as I can tell.

This patch is saying the opposite though. Something else drives the
signal, but the signal is also routed to the SoC to sample the state.

Rob