linux-kernel - Re: [PATCH 5/7] dt-bindings: pinctrl: add compatible for Allwinner A523/T527

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Message-ID: <20241120101228.26bbf100@donnerap.manchester.arm.com>
Date: Wed, 20 Nov 2024 10:12:28 +0000
From: Andre Przywara <andre.przywara@....com>
To: Chen-Yu Tsai <wens@...e.org>
Cc: Linus Walleij <linus.walleij@...aro.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Jernej Skrabec <jernej.skrabec@...il.com>, Samuel
 Holland <samuel@...lland.org>, linux-gpio@...r.kernel.org,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/7] dt-bindings: pinctrl: add compatible for Allwinner
 A523/T527

On Wed, 13 Nov 2024 16:50:19 +0800
Chen-Yu Tsai <wens@...e.org> wrote:

Hi Chen-Yu,

sorry for the late reply, I was away for a week.

> On Mon, Nov 11, 2024 at 8:58 AM Andre Przywara <andre.przywara@....com> wrote:
> >
> > The A523 contains a pin controller similar to previous SoCs, although
> > using 10 GPIO banks (PortB-PortK), all of them being IRQ capable.
> > This introduces a new style of binding, where the pinmux values for each
> > pin group is stored in the new "allwinner,pinmux" property in the DT
> > node, instead of requiring every driver to store a mapping between the
> > function names and the required pinmux.
> >
> > Add the new name to the list of compatible strings, and required it to
> > have 10 interrupts described. Also add the new pinmux property.
> >
> > Signed-off-by: Andre Przywara <andre.przywara@....com>
> > ---
> >  .../pinctrl/allwinner,sun4i-a10-pinctrl.yaml  | 23 +++++++++++++++++--
> >  1 file changed, 21 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/pinctrl/allwinner,sun4i-a10-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/allwinner,sun4i-a10-pinctrl.yaml
> > index 4502405703145..6fc18e92e1e94 100644
> > --- a/Documentation/devicetree/bindings/pinctrl/allwinner,sun4i-a10-pinctrl.yaml
> > +++ b/Documentation/devicetree/bindings/pinctrl/allwinner,sun4i-a10-pinctrl.yaml
> > @@ -56,6 +56,8 @@ properties:
> >        - allwinner,sun50i-h6-r-pinctrl
> >        - allwinner,sun50i-h616-pinctrl
> >        - allwinner,sun50i-h616-r-pinctrl
> > +      - allwinner,sun55i-a523-pinctrl
> > +      - allwinner,sun55i-a523-r-pinctrl
> >        - allwinner,suniv-f1c100s-pinctrl
> >        - nextthing,gr8-pinctrl
> >
> > @@ -64,7 +66,7 @@ properties:
> >
> >    interrupts:
> >      minItems: 1
> > -    maxItems: 8
> > +    maxItems: 10
> >      description:
> >        One interrupt per external interrupt bank supported on the
> >        controller, sorted by bank number ascending order.
> > @@ -119,13 +121,17 @@ patternProperties:
> >          $ref: /schemas/types.yaml#/definitions/uint32
> >          enum: [10, 20, 30, 40]
> >
> > +      allwinner,pinmux:
> > +        $ref: /schemas/types.yaml#/definitions/uint32-array
> > +        description: pinmux selector for each pin
> > +  
> 
> Why not just the standard "pinmux" property, as given in
> Documentation/devicetree/bindings/pinctrl/pinmux-node.yaml

I had it like this in my last post two years ago, but learned from
LinusW [1] that the generic pinmux property has a slightly different
meaning, and abusing it for just the pinmux index values would not match
the generic definition.
We *could* use the generic definition, but then this would include what's
in the "pins" property, like I sketched out in the cover letter, as an
alternative to this approach:
	pinmux = <SUNXI_PIN(PB, 9, 2)>, <SUNXI_PIN(PB, 10, 2)>;
Where the SUNXI_PIN macro would combine the pin number and the pinmux into
one 32-bit cell. See the Apple GPIO DT nodes for an example.
This looks indeed nicer, but requires quite some rewrite of the existing
pinctrl driver, AFAICS.

[1] Previous reply from LinusW:
https://lore.kernel.org/linux-sunxi/CACRpkdbMc-Q6wjgsiddu6-tWC1dt2uFk+4LyerMdgFk2KRGK4w@mail.gmail.com/

> 
> >      required:
> >        - pins
> >        - function  
> 
> This section should be made to apply only to the existing
> compatibles? Maybe we could just split the files and have
> a clean slate for sun55i?

Yeah, I couldn't find a good example how to make it *required* for one
compatible and *not allowed* for all the others. But creating a whole new
file is actually a good idea, as this also avoids adding another case to
the already quite indented if-else cascade.

Cheers,
Andre

> ChenYu
> 
> >      additionalProperties: false
> >
> > -  "^vcc-p[a-ilm]-supply$":
> > +  "^vcc-p[a-klm]-supply$":
> >      description:
> >        Power supplies for pin banks.
> >
> > @@ -156,6 +162,17 @@ allOf:
> >          - interrupts
> >          - interrupt-controller
> >
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          enum:
> > +            - allwinner,sun55i-a523-pinctrl
> > +
> > +    then:
> > +      properties:
> > +        interrupts:
> > +          minItems: 10
> > +
> >    - if:
> >        properties:
> >          compatible:
> > @@ -166,6 +183,7 @@ allOf:
> >        properties:
> >          interrupts:
> >            minItems: 8
> > +          maxItems: 8
> >
> >    - if:
> >        properties:
> > @@ -244,6 +262,7 @@ allOf:
> >              - allwinner,sun8i-v3s-pinctrl
> >              - allwinner,sun9i-a80-r-pinctrl
> >              - allwinner,sun50i-h6-r-pinctrl
> > +            - allwinner,sun55i-a523-r-pinctrl
> >
> >      then:
> >        properties:
> > --
> > 2.46.2
> >