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

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Date: Wed, 29 May 2024 13:54:34 -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

Hi David,

On 5/25/24 12:49 PM, David Lechner wrote:
> On 5/24/24 4:44 PM, Judith Mendez wrote:
>> 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
>>
> 
> I wasn't suggesting to remove clock-names from the bindings, just
> deprecate that property in this binding and not use it with any
> new compatibles.
> 
> In the AM62x technical reference manual, it looks like it calls
> the functional and interface clock FICLK rather than FCK. So
> I'm just suggesting maybe it just easier to not give it a name
> rather than try to get the right name? No name will work with
> any future SoCs as well. :-)

Understood, so I will make clock-names optional for ti,am3352-eqep
compatible and not allowed for ti,am62-eqep compatible.

Thanks for your feedback (:

~ Judith
>