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SubjectRe: [PATCH v3 1/2] dt-bindings: net: motorcomm: Add pad driver strength cfg
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Re: [PATCH v3 1/2] dt-bindings: net: motorcomm: Add pad driver strength cfg
From: Guo Samin <samin.guo@starfivetech.com>
to: Conor Dooley <conor@kernel.org>; Andrew Lunn <andrew@lunn.ch>
data: 2023/5/29

> Re: [PATCH v3 1/2] dt-bindings: net: motorcomm: Add pad driver strength cfg
> From: Conor Dooley <conor@kernel.org>
> to: Samin Guo <samin.guo@starfivetech.com>
> data: 2023/5/27
>
>> On Fri, May 26, 2023 at 05:05:01PM +0800, Samin Guo wrote:
>>> The motorcomm phy (YT8531) supports the ability to adjust the drive
>>> strength of the rx_clk/rx_data, the value range of pad driver
>>> strength is 0 to 7.
>>>
>>> Signed-off-by: Samin Guo <samin.guo@starfivetech.com>
>>> ---
>>> .../devicetree/bindings/net/motorcomm,yt8xxx.yaml | 12 ++++++++++++
>>> 1 file changed, 12 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/net/motorcomm,yt8xxx.yaml b/Documentation/devicetree/bindings/net/motorcomm,yt8xxx.yaml
>>> index 157e3bbcaf6f..29a1997a1577 100644
>>> --- a/Documentation/devicetree/bindings/net/motorcomm,yt8xxx.yaml
>>> +++ b/Documentation/devicetree/bindings/net/motorcomm,yt8xxx.yaml
>>> @@ -52,6 +52,18 @@ properties:
>>> for a timer.
>>> type: boolean
>>>
>>> + motorcomm,rx-clk-driver-strength:
>>> + description: drive strength of rx_clk pad.
>>> + $ref: /schemas/types.yaml#/definitions/uint32
>>> + enum: [ 0, 1, 2, 3, 4, 5, 6, 7 ]
>>
>> I think you should use minimum & maximum instead of these listed out
>> enums.
>
> Thanks Conor, This can be improved in the next version.
>
> You have also had this comment since v1 & were reminded of it on
>> v2 by Krzysztof: "What do the numbers mean? What are the units? mA?"
>>
>
>
> The good news is that we just got some data about units from Motorcomm.
> Maybe I can post the data show of the unit later after I get the complete data.
>

Hi Andrew & Conor,

Sorry, haven't updated in a while.
I just got the detailed data of Driver Strength(DS) from Motorcomm , which applies to both rx_clk and rx_data.

|----------------------|
| ds map table |
|----------------------|
| DS(3b) | Current (mA)|
|--------|-------------|
| 000 | 1.20 |
| 001 | 2.10 |
| 010 | 2.70 |
| 011 | 2.91 |
| 100 | 3.11 |
| 101 | 3.60 |
| 110 | 3.97 |
| 111 | 4.35 |
|--------|-------------|

Since these currents are not integer values and have no regularity, it is not very good to use in the drive/dts in my opinion.

Therefore, I tend to continue to use DS(0-7) in dts/driver, and adding a description of the current value corresponding to DS in dt-bindings.

Like This:

+ motorcomm,rx-clk-driver-strength:
+ description: drive strength of rx_clk pad.
+ |----------------------|
+ | rx_clk ds map table |
+ |----------------------|
+ | DS(3b) | Current (mA)|
+ | 000 | 1.20 |
+ | 001 | 2.10 |
+ | 010 | 2.70 |
+ | 011 | 2.91 |
+ | 100 | 3.11 |
+ | 101 | 3.60 |
+ | 110 | 3.97 |
+ | 111 | 4.35 |
+ |--------|-------------|
+ $ref: /schemas/types.yaml#/definitions/uint32
+ enum: [ 0, 1, 2, 3, 4, 5, 6, 7 ]
+ default: 3
+
+ motorcomm,rx-data-driver-strength:
+ description: drive strength of rx_data/rx_ctl rgmii pad.
+ |----------------------|
+ | rx_data ds map table |
+ |----------------------|
+ | DS(3b) | Current (mA)|
+ | 000 | 1.20 |
+ | 001 | 2.10 |
+ | 010 | 2.70 |
+ | 011 | 2.91 |
+ | 100 | 3.11 |
+ | 101 | 3.60 |
+ | 110 | 3.97 |
+ | 111 | 4.35 |
+ |--------|-------------|
+ $ref: /schemas/types.yaml#/definitions/uint32
+ enum: [ 0, 1, 2, 3, 4, 5, 6, 7 ]
+ default: 3
+


Or use minimum & maximum instead of these listed out enums(Suggested by Conor)

+ motorcomm,rx-clk-driver-strength:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ default: 3
+ minimum: 0
+ maximum: 7
+ description: drive strength of rx_clk pad.
+ |----------------------|
+ | rx_clk ds map table |
+ |----------------------|
+ | DS(3b) | Current (mA)|
+ | 000 | 1.20 |
+ | 001 | 2.10 |
+ | 010 | 2.70 |
+ | 011 | 2.91 |
+ | 100 | 3.11 |
+ | 101 | 3.60 |
+ | 110 | 3.97 |
+ | 111 | 4.35 |
+ |--------|-------------|
+
+ motorcomm,rx-data-driver-strength:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ default: 3
+ minimum: 0
+ maximum: 7
+ description: drive strength of rx_data/rx_ctl rgmii pad.
+ |----------------------|
+ | rx_data ds map table |
+ |----------------------|
+ | DS(3b) | Current (mA)|
+ | 000 | 1.20 |
+ | 001 | 2.10 |
+ | 010 | 2.70 |
+ | 011 | 2.91 |
+ | 100 | 3.11 |
+ | 101 | 3.60 |
+ | 110 | 3.97 |
+ | 111 | 4.35 |
+ |--------|-------------|
+


Looking forward to your suggestions.


Best regards,
Samin

>
>
>> This information should go into the binding, not sit in a thread on a
>> mailing list that noone will look at when trying to write a DT :(
>>
>> Thanks,
>> Conor.
>>
>
> Yes,when we have the complete 'unit' data, it will be placed in DT.
>
> Best regards,
> Samin
>
>>> + default: 3
>>> +
>>> + motorcomm,rx-data-driver-strength:
>>> + description: drive strength of rx_data/rx_ctl rgmii pad.
>>> + $ref: /schemas/types.yaml#/definitions/uint32
>>> + enum: [ 0, 1, 2, 3, 4, 5, 6, 7 ]
>>> + default: 3
>>> +
>>> motorcomm,tx-clk-adj-enabled:
>>> description: |
>>> This configuration is mainly to adapt to VF2 with JH7110 SoC.
>>> --
>>> 2.17.1
>>>

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