Message-ID: <1735add6-4a6a-452b-bf26-1cf19c95493e@microchip.com>
Date: Thu, 21 Mar 2024 12:00:56 +0000
From: <Parthiban.Veerasooran@...rochip.com>
To: <krzysztof.kozlowski@...aro.org>, <conor@...nel.org>, <andrew@...n.ch>
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Subject: Re: [PATCH net-next v3 12/12] dt-bindings: net: add Microchip's
 LAN865X 10BASE-T1S MACPHY

Hi Krzysztof,

On 21/03/24 2:10 pm, Krzysztof Kozlowski wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On 21/03/2024 09:38, Parthiban.Veerasooran@...rochip.com wrote:
>> Hi Krzysztof,
>>
>> On 20/03/24 3:23 pm, Krzysztof Kozlowski wrote:
>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>
>>> On 20/03/2024 09:40, Parthiban.Veerasooran@...rochip.com wrote:
>>>> Hi Conor & Andrew,
>>>>
>>>> Please find my reply below by consolidating other two emails comments
>>>> related to this.
>>>>
>>>> On 07/03/24 12:31 am, Conor Dooley wrote:
>>>>> On Wed, Mar 06, 2024 at 07:48:57PM +0100, Andrew Lunn wrote:
>>>>>>>> +description:
>>>>>>>> +  The LAN8650/1 combines a Media Access Controller (MAC) and an Ethernet
>>>>>>>> +  PHY to enable 10BASE‑T1S networks. The Ethernet Media Access Controller
>>>>>>>> +  (MAC) module implements a 10 Mbps half duplex Ethernet MAC, compatible
>>>>>>>> +  with the IEEE 802.3 standard and a 10BASE-T1S physical layer transceiver
>>>>>>>> +  integrated into the LAN8650/1. The communication between the Host and
>>>>>>>> +  the MAC-PHY is specified in the OPEN Alliance 10BASE-T1x MACPHY Serial
>>>>>>>> +  Interface (TC6).
>>>>>>>> +
>>>>>>>> +allOf:
>>>>>>>> +  - $ref: ethernet-controller.yaml#
>>>>>>>> +
>>>>>>>> +properties:
>>>>>>>> +  compatible:
>>>>>>>> +    oneOf:
>>>>>>>> +      - items:
>>>>>>>> +          - const: microchip,lan8650
>>>>>>>> +          - const: microchip,lan8651
>>>>>>> The order here is wrong, lan8561 needs to come before the fallback of
>>>>>>> lan8650.
>>>>>> I don't think it is a fallback. There are two devices, and hence two
>>>>>> different compatibles. So i suspect the -items: is wrong here?
>>>>> It'd just be a two entry enum then, but I did take a quick look at the
>>>>> driver earlier and saw:
>>>>> +static const struct of_device_id lan865x_dt_ids[] = {
>>>>> +    { .compatible = "microchip,lan8650" },
>>>>> +    { .compatible = "microchip,lan8651" },
>>>>> +    { /* Sentinel */ }
>>>>> +};
>>>>>
>>>>> That, along with no other of_device_is_compatible() type operations
>>>>> made me think that having a fallback actually was suitable.
>>>>>
>>>>> You cropped it out, but the patch had:
>>>>>> +  compatible:
>>>>>> +    oneOf:
>>>>>> +      - items:
>>>>>> +          - const: microchip,lan8650
>>>>>> +          - const: microchip,lan8651
>>>>>> +      - enum:
>>>>>> +          - microchip,lan8650
>>>>> So it doesn't appear to be an accidental items in place of an enum,
>>>>> since the other compatible is in another enum.
>>>> As per Andrew's comment in another email, both LAN8650 and LAN8651 are
>>>> two different variants but they both share almost all characteristics
>>>> except one thing that is LAN8651 has "Single 3.3V supply with integrated
>>>> 1.8V regulator" which doesn't have anything to do with driver. That's
>>>
>>> So why this is not reflected in your driver? Why didn't you address that
>>> part, but ignored?
>> No, it is not ignored. This difference is specific to hardware and there
>> is no configuration/setting to be done from driver.
>>>
>>>> why I have kept them as fallback as Conor said in this email. Hope you
>>>> all OK with this.
>>>
>>> Did you read the feedback? Your response is not solving here anything.
>>> How 8650 can be used twice? Please point me to DTS showing both usages.
>> May be I have a misunderstanding here. Let's clarify it.
>>
>> LAN8650 and LAN8651 both are two different variants but both implements
>> same functionality. The only difference is LAN8651 has "Single 3.3V
>> supply with integrated" where LAN8650 doesn't have this. This is
>> hardware specific difference and there is no configuration/setting to be
>> done in the driver specific to this difference in the LAN8651. So
>> basically the driver can support for both variants without any
>> additional settings.
>>
>> LAN8650: https://www.microchip.com/en-us/product/lan8650
>> LAN8651: https://www.microchip.com/en-us/product/lan8651
>>
>> The below link shows the difference between them,
>> https://www.microchip.com/en-us/product-comparison.lan8650.lan8651
>>
>> With the above details, I would change the microchip,lan865x.yaml with
>> the below details.
>>
>> compatible:
>>     enum:
>>       - microchip,lan8650
>>       - microchip,lan8651
>>
>> And in the lan865x.c, I would remove the below line because
>> .compatible = "microchip,lan8650" already supports for LAN8651 as well.
>>
>> .compatible = "microchip,lan8651"
>>
>> Let me know your opinion on this proposal? or do you have any
>> misunderstanding here?
> 
> It's still wrong. Upstream your DTS and then test it. You will
> immediately see that it does not work. So first make it working, then
> send code to review.
Sorry for the inconvenience. I did the below changes in my 
microchip,lan865x.yaml file and executed dt_binding_check. It 
successfully created the microchip,lan865x.example.dts without any 
errors. Herewith I have attached the updated microchip,lan865x.yaml file 
and the generated microchip,lan865x.example.dts file for your reference.

properties:
   compatible:
     oneOf:
       - items:
           - const: microchip,lan8651
           - const: microchip,lan8650
....

       ethernet@0 {
         compatible = "microchip,lan8651", "microchip,lan8650";
         reg = <0>;
         pinctrl-names = "default";
         pinctrl-0 = <&eth0_pins>;
         interrupt-parent = <&gpio>;
         interrupts = <6 IRQ_TYPE_EDGE_FALLING>;
         local-mac-address = [04 05 06 01 02 03];
         spi-max-frequency = <15000000>;
       };

LAN8650 is the fallback here as the driver uses the compatible string as 
"microchip,lan8650". I am using LAN8651 in my RPI4 test setup. So I 
added the below compatible string

compatible = "microchip,lan8651", "microchip,lan8650"

in my RPI 4 DT overlay file and tested in my RPI 4 test setup and it 
worked well.

Herewith I have attached my RPI 4 dt overlay file lan8651-overlay.dts 
for your reference.

Hope this is OK now?

Best regards,
Parthiban V
> 
> Best regards,
> Krzysztof
> 
> 

Download attachment "microchip,lan865x.yaml" of type "application/x-yaml" (2021 bytes)

Download attachment "microchip,lan865x.example.dts" of type "audio/vnd.dts" (1028 bytes)

Download attachment "lan8651-overlay.dts" of type "audio/vnd.dts" (1058 bytes)

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