Re: [v9 1/4] dt-bindings: i2c: Add Maxim MAX735x/MAX736x variants

Serge Semin
2022-10-09T18:03:49Z

On Sun, Oct 09, 2022 at 05:25:22PM +0200, Krzysztof Kozlowski wrote:
> On 08/10/2022 13:50, Serge Semin wrote:
> > On Fri, Oct 07, 2022 at 09:53:50AM +0200, Patrick Rudolph wrote:
> >> Update the pca954x bindings to add support for the Maxim MAX735x/MAX736x
> >> chips. The functionality will be provided by the exisintg pca954x driver.
> >>
> >> While on it make the interrupts support conditionally as not all of the
> >> existing chips have interrupts.
> >>
> >> For chips that are powered off by default add an optional regulator
> >> called vdd-supply.
> >>
> >> Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
> >> ---
> >> .../bindings/i2c/i2c-mux-pca954x.yaml | 39 ++++++++++++++++---
> >> 1 file changed, 34 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.yaml b/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.yaml
> >> index 9f1726d0356b..efad0a95806f 100644
> >> --- a/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.yaml
> >> +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.yaml
> >> @@ -4,21 +4,25 @@
> >> $id: http://devicetree.org/schemas/i2c/i2c-mux-pca954x.yaml#
> >> $schema: http://devicetree.org/meta-schemas/core.yaml#
> >>
> >> -title: NXP PCA954x I2C bus switch
> >> +title: NXP PCA954x I2C and compatible bus switches
> >>
> >> maintainers:
> >> - Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> >>
> >> description:
> >> - The binding supports NXP PCA954x and PCA984x I2C mux/switch devices.
> >> -
> >
> >> -allOf:
> >> - - $ref: /schemas/i2c/i2c-mux.yaml#
> >
> > Why do you move the allOf statement to the bottom of the schema?
>

> Because it goes with 'ifs' at the bottom of the schema...

Is there a requirement to move the allOf array to the bottom of the
schema if it contains the 'if' statement? If only there were some
kernel doc with all such implicit conventions...

>
> >
> >> + The binding supports NXP PCA954x and PCA984x I2C mux/switch devices,
> >> + and the Maxim MAX735x and MAX736x I2C mux/switch devices.
> >
> > What about combining the sentence: "The binding supports NXP
> > PCA954x/PCA984x and Maxim MAX735x/MAX736x I2C mux/switch devices." ?
> > Currently it does look a bit bulky.
>
> Drop "The binding supports". Instead describe the hardware.
>
> >
> >>
> >> properties:
> >> compatible:
> >> oneOf:
> >> - enum:
> >> + - maxim,max7356
> >> + - maxim,max7357
> >> + - maxim,max7358
> >> + - maxim,max7367
> >> + - maxim,max7368
> >> + - maxim,max7369
> >> - nxp,pca9540
> >> - nxp,pca9542
> >> - nxp,pca9543
> >> @@ -59,10 +63,33 @@ properties:
> >> description: if present, overrides i2c-mux-idle-disconnect
> >> $ref: /schemas/mux/mux-controller.yaml#/properties/idle-state
> >>
> >> + vdd-supply:
> >> + description: A voltage regulator supplying power to the chip.
> >> +
> >> required:
> >> - compatible
> >> - reg
> >>
> >> +allOf:
> >> + - $ref: /schemas/i2c/i2c-mux.yaml#
> >> + - if:
> >> + not:
> >> + properties:
> >> + compatible:
> >> + contains:
> >> + enum:
> >> + - maxim,max7367
> >> + - maxim,max7369
> >> + - nxp,pca9542
> >> + - nxp,pca9543
> >> + - nxp,pca9544
> >> + - nxp,pca9545
> >> + then:
> >
> >> + properties:
> >> + interrupts: false
> >> + "#interrupt-cells": false
> >> + interrupt-controller: false
> >
> > I'd suggest to add an opposite definition. Evaluate the properties for
> > the devices which expect them being evaluated instead of falsing their
> > existence for the devices which don't support the interrupts.
>

> The properties rather should be defined in top-level than in "if", so I
> am not sure how would you want to achieve opposite way.

With one more implicit convention like "preferably define the
properties in the top-level than in if" of course I can't. Otherwise I
thought something like this would work:
+allOf:
+ - ...
+ - if:
+ properties:
+ compatible:
+ contains:
+ enum: [...]
+ then:
+ properties:
+ interrupts: ...
+ "#interrupt-cells": ...
+ interrupt-controller: ...
...
- interrupts:
- "#interrupt-cells":
- interrupt-controller: ...

With unevaluatedProperties set to false and evaluation performed for
the particular compatibles such schema shall work with the same
semantic.

-Sergey

>
>
> Best regards,
> Krzysztof
>