Re: [EXT] Re: [PATCH 2/2] dt-bindings: i2c: imx-lpi2c: Add bus recovery example

[Krzysztof Kozlowski]

On 31/05/2023 12:22, Carlos Song wrote:
> Hi,
> 	Thanks for you reply. 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
>> Sent: Tuesday, May 30, 2023 10:59 PM
>> To: Carlos Song <carlos.song@xxxxxxx>; Aisheng Dong
>> <aisheng.dong@xxxxxxx>; shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx;
>> kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; robh+dt@xxxxxxxxxx;
>> krzysztof.kozlowski+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx;
>> Anson.Huang@xxxxxxx
>> Cc: Clark Wang <xiaoning.wang@xxxxxxx>; Bough Chen
>> <haibo.chen@xxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>;
>> linux-i2c@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx;
>> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
>> Subject: [EXT] Re: [PATCH 2/2] dt-bindings: i2c: imx-lpi2c: Add bus recovery
>> example
>>
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>>
>> On 29/05/2023 09:43, carlos.song@xxxxxxx wrote:
>>> From: Clark Wang <xiaoning.wang@xxxxxxx>
>>>
>>> Add i2c bus recovery configuration example.
>>
>> Why? That's just example... also with coding style issue.
>>
>>>
>>> Signed-off-by: Clark Wang <xiaoning.wang@xxxxxxx>
>>> Signed-off-by: Carlos Song <carlos.song@xxxxxxx>
>>> ---
>>>  .../devicetree/bindings/i2c/i2c-imx-lpi2c.yaml   | 16 ++++++++++++++++
>>>  1 file changed, 16 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.yaml
>>> b/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.yaml
>>> index 4656f5112b84..62ee457496e4 100644
>>> --- a/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.yaml
>>> +++ b/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.yaml
>>> @@ -58,6 +58,16 @@ properties:
>>>    power-domains:
>>>      maxItems: 1
>>>
>>> +  pinctrl-names:
>>> +    minItems: 1
>>> +    maxItems: 3
>>
>> What's the benefit of this? Entries should be defined but without it is not really
>> helpful. Anyway not explained in commit msg.
>>
>>> +
>>> +  scl-gpios:
>>> +    maxItems: 1
>>> +
>>> +  sda-gpios:
>>> +    maxItems: 1
>>
>> You don't need these two. Anyway not explained in commit msg.
>>
> 
> Sorry for confusing you with the poor commit log and without
> full description.
> 
> The reason why we need sending the patch for dt-binding is :
> We sent out a patch for I.MX LPI2C bus support recovery function.
> When LPI2C use recovery function, lpi2c controller need to switch the 
> SCL pin and SDA pin to their GPIO function.  So I think the scl-gpio and
> sda-gpio property need to be added in the dt-bindings.

Why do you think they are not in the bindings already?

> 
> And alternative pinmux settings are described in a separate pinctrl state "gpio". 
> So maybe "gpio" pinctrl item need to be added.
> 
> I would like to know whether the above changes are really unnecessary according to above case?
> Or because of the vague commit log, you are misled and think that our patch is not necessary to add examples.


I claim your patch has zero effect. Can you prove otherwise?

Proof is with DTS example and result of dtbs_check.

> 
> Is there no need to add sda/scl-gpios property or no need to add maxItems: 1?

I think entire patch can be dropped.

> We also find the sci-gpio and sda-gpio have been defined in the ref: /schemas/i2c/i2c-controller.yaml. 
> So is this the root cause of no need to add these properties?

Yes.


Best regards,
Krzysztof