linux-kernel - Re: [RFC PATCH 6/7] dt-bindings: motion: Add adi,tmc5240 bindings

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Message-ID: <99c437db-6341-4d56-b99e-3ed3f2b8219d@kernel.org>
Date: Fri, 28 Feb 2025 10:35:38 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: David Jander <david@...tonic.nl>
Cc: linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
 Jonathan Corbet <corbet@....net>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, devicetree@...r.kernel.org,
 linux-doc@...r.kernel.org, Nuno Sa <nuno.sa@...log.com>,
 Jonathan Cameron <jic23@...nel.org>, Oleksij Rempel <o.rempel@...gutronix.de>
Subject: Re: [RFC PATCH 6/7] dt-bindings: motion: Add adi,tmc5240 bindings

On 28/02/2025 09:48, David Jander wrote:
> 
> Dear Krzysztof,
> 
> Thanks for reviewing...
> 
> On Fri, 28 Feb 2025 08:11:04 +0100
> Krzysztof Kozlowski <krzk@...nel.org> wrote:
> 
>> On Thu, Feb 27, 2025 at 05:28:22PM +0100, David Jander wrote:
>> [...]
>>> +
>>> +  enable-supply:
>>> +    description: Optional external enable supply to control SLEEPn pin. Can  
>>
>> That's odd. regular pins are not supplies. This must be named after
>> physical supplies. There is vdd18, vcc, vcp but nothing about enable
>> supply in datasheet.
>>
>>> +      be shared between several controllers.  
>>
>> Second sentence is both redundant and really not relevant to this
>> binding. It's not this binding which decides about sharing.
> 
> Good point. I think I should drop the whole property, since it is indeed
> irrelevant. If extra supplies need to be specified, they always can be, right?

You should specify all supplies now, because hardware should be fully
described by binding and DTS.

What's more, the necessary supplies (according to datasheet) should be
required, not optional.

> 
>>> +
>>> +  clocks:
>>> +    maxItems: 1
>>> +
>>> +required:
>>> +  - compatible
>>> +  - reg
>>> +  - interrupts
>>> +  - clocks
>>> +
>>> +allOf:
>>> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
>>> +  - $ref: /schemas/motion/common.yaml#
>>> +
>>> +unevaluatedProperties: false
>>> +
>>> +examples:
>>> +  - |
>>> +    spi {
>>> +        #address-cells = <1>;
>>> +        #size-cells = <0>;
>>> +
>>> +        motor@0 {
>>> +            compatible = "adi,tmc5240";
>>> +            reg = <0>;
>>> +            interrupts-extended = <&gpiok 7 0>;  
>>
>> Include header and use standard defines for flags.
> 
> Thanks. I didn't know I could include them here... will fix this.
> 
>>
>>> +            clocks = <&clock_tmc5240>;
>>> +            enable-supply = <&stpsleepn>;
>>> +            spi-max-frequency = <1000000>;  
>>
>> Where are any other properties from common schema?
> 
> The properties in common.yaml are optional. Do I need to explicitly specify
> this somehow (they are not listed under "required:")?

The common says default=1, so it is fine to skip them if that default
makes sense here.

Anyway, it's fine.


> In fact, the tmc5240 driver has its own known constants for these properties
> that it fills in. One can overrule them here if needed, but I suppose in the
> case of the tmc5240 the regular use-case is not to do that. Should I maybe add
> a second example that overrules the defaults?

Not necessarily, one real-world, complete example is enough.

Best regards,
Krzysztof