linux-kernel - Re: [PATCH v2 2/8] dt-bindings: counter: Add new ti,am62-eqep compatible

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Date: Fri, 24 May 2024 16:44:05 -0500
From: Judith Mendez <jm@...com>
To: David Lechner <david@...hnology.com>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon
	<will@...nel.org>,
        William Breathitt Gray <william.gray@...aro.org>
CC: <linux-arm-kernel@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-iio@...r.kernel.org>,
        Nishanth Menon
	<nm@...com>, Vignesh Raghavendra <vigneshr@...com>
Subject: Re: [PATCH v2 2/8] dt-bindings: counter: Add new ti,am62-eqep
 compatible

On 5/24/24 3:57 PM, David Lechner wrote:
> On 5/24/24 3:50 PM, David Lechner wrote:
>> On 5/23/24 6:15 PM, Judith Mendez wrote:
>>> Add new compatible ti,am62-eqep for TI K3 devices. If a device
>>> uses this compatible, require power-domains property.
>>>
>>> Since there is only one functional and interface clock for eqep,
>>> clock-names is not really required. The clock-name also changed
>>> for TI K3 SoCs so make clock-names optional for the new compatible
>>> since there is only one clock that is routed to the IP.
>>>
>>> While we are here, add an example using ti,am62-eqep compatible.
>>>
>>> Signed-off-by: Judith Mendez <jm@...com>
>>> ---
>>> Changes since v1:
>>> - Fix eqep binding for new compatible, require
>>>   power-domains for new compatible
>>> ---
>>>   .../devicetree/bindings/counter/ti-eqep.yaml  | 53 +++++++++++++++++--
>>>   1 file changed, 48 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/counter/ti-eqep.yaml b/Documentation/devicetree/bindings/counter/ti-eqep.yaml
>>> index 85f1ff83afe72..c4bb0231f166a 100644
>>> --- a/Documentation/devicetree/bindings/counter/ti-eqep.yaml
>>> +++ b/Documentation/devicetree/bindings/counter/ti-eqep.yaml
>>> @@ -11,7 +11,9 @@ maintainers:
>>>   
>>>   properties:
>>>     compatible:
>>> -    const: ti,am3352-eqep
>>> +    enum:
>>> +      - ti,am3352-eqep
>>> +      - ti,am62-eqep
>>>   
>>>     reg:
>>>       maxItems: 1
>>> @@ -21,19 +23,43 @@ properties:
>>>       maxItems: 1
>>>   
>>>     clocks:
>>> -    description: The clock that determines the SYSCLKOUT rate for the eQEP
>>> -      peripheral.
>>> +    description: The functional and interface clock that determines the clock
>>> +      rate for the eQEP peripheral.
>>>       maxItems: 1
>>>   
>>>     clock-names:
>>> -    const: sysclkout
>>> +    enum:
>>> +      - sysclkout
>>> +      - fck
>>> +
>>
>> If we are making this optional for ti,am62-eqep, why add a new name?
>>
>> Also, we could change the description to say that sysclockout is not a
>> great name but is required for backwards compatibility.
>>
>>> +  power-domains:
>>> +    maxItems: 1
>>> +
>>> +allOf:
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            enum:
>>> +              - ti,am3352-eqep
>>> +    then:
>>> +      required:
>>> +        - clock-names
> 
> I just looked at the Linux driver for this and the clock name is
> not used in the driver. So we could probably just deprecate the
> clock-names property here and not make it required for
> ti,am3352-eqep (and not allowed for any new compatibles as
> suggested below).

We could do this, although I was under the impression that we should
not drop DT properties just because the linux driver isn't using it,
that is why I went with keeping clock-names around for am335x compatible
and making it optional for am62x compatible.

But if it is all the same, we could drop the the DT property.

~ Judith

> 
>>
>> What if we just add
>>
>>    else:
>>      clock-names: false
>>
>> since there is only one clock and not worry about the name?
>>
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            enum:
>>> +              - ti,am62-eqep
>>> +    then:
>>> +      required:
>>> +        - power-domains
>>>   
>>>   required:
>>>     - compatible
>>>     - reg
>>>     - interrupts
>>>     - clocks
>>> -  - clock-names
>>>   
>