linux-kernel - Re: [PATCH 2/3] dt-bindings: pinctrl: rockchip: Add io domain properties

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Message-ID: <20230906072121.GA492117@pengutronix.de>
Date:   Wed, 6 Sep 2023 09:21:21 +0200
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     Robin Murphy <robin.murphy@....com>
Cc:     linux-rockchip@...ts.infradead.org,
        Heiko Stuebner <heiko@...ech.de>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-gpio@...r.kernel.org,
        kernel@...gutronix.de,
        Quentin Schulz <quentin.schulz@...obroma-systems.com>,
        Michael Riesch <michael.riesch@...fvision.net>,
        Linus Walleij <linus.walleij@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Subject: Re: [PATCH 2/3] dt-bindings: pinctrl: rockchip: Add io domain
 properties

On Tue, Sep 05, 2023 at 10:03:20AM +0100, Robin Murphy wrote:
> On 2023-09-04 12:58, Sascha Hauer wrote:
> > Add rockchip,io-domains property to the Rockchip pinctrl driver. This
> > list of phandles points to the IO domain device(s) the pins of the
> > pinctrl driver are supplied from.
> > 
> > Also a rockchip,io-domain-boot-on property is added to pin groups
> > which can be used for pin groups which themselves are needed to access
> > the regulators an IO domain is driven from.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> > ---
> >   .../bindings/pinctrl/rockchip,pinctrl.yaml          | 13 ++++++++++++-
> >   1 file changed, 12 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/pinctrl/rockchip,pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/rockchip,pinctrl.yaml
> > index 10c335efe619e..92075419d29cf 100644
> > --- a/Documentation/devicetree/bindings/pinctrl/rockchip,pinctrl.yaml
> > +++ b/Documentation/devicetree/bindings/pinctrl/rockchip,pinctrl.yaml
> > @@ -62,6 +62,11 @@ properties:
> >         Required for at least rk3188 and rk3288. On the rk3368 this should
> >         point to the PMUGRF syscon.
> > +  rockchip,io-domains:
> > +    $ref: /schemas/types.yaml#/definitions/phandle-array
> > +    description:
> > +      Phandles to io domains
> > +
> >     "#address-cells":
> >       enum: [1, 2]
> > @@ -137,7 +142,13 @@ additionalProperties:
> >               - description:
> >                   The phandle of a node contains the generic pinconfig options
> >                   to use as described in pinctrl-bindings.txt.
> > -
> > +      rockchip,io-domain-boot-on:
> 
> I don't think "on" is a particularly descriptive or useful property name for
> something that has no "off" state.

In fact it has an "off" state. A IO Domain can be disabled in the SoC
registers and also the corresponding regulator can be disabled.

> Furthermore it's no help at all if the DT
> consumer *is* the bootloader that's expected to configure this in the first
> place. IMO it would seem a lot more sensible to have an integer (or enum)
> property which describes the actual value for the initial I/O domain
> setting.

I agree though that a particular setting instead of a boolean is better
and could help the bootloader.

> Then Linux can choose to assume the presence of the property at all
> implies that the bootloader should have set it up already, but also has the
> option of actively enforcing it as well if we want to.

Ok.

Thanks,
 Sascha

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