linux-kernel - Re: [PATCH v1 1/2] dt-bindings: net: motorcomm: Add pad driver strength cfg

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Message-ID: <2c43c2e3-afdb-6bee-37bc-655c0a1b0762@starfivetech.com>
Date:   Thu, 27 Apr 2023 14:43:17 +0800
From:   Guo Samin <samin.guo@...rfivetech.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <netdev@...r.kernel.org>, Peter Geis <pgwipeout@...il.com>,
        Frank <Frank.Sae@...or-comm.com>,
        "David S . Miller" <davem@...emloft.net>,
        "Eric Dumazet" <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Yanhong Wang <yanhong.wang@...rfivetech.com>
Subject: Re: [PATCH v1 1/2] dt-bindings: net: motorcomm: Add pad driver
 strength cfg

Re: [PATCH v1 1/2] dt-bindings: net: motorcomm: Add pad driver strength cfg
From: Andrew Lunn <andrew@...n.ch>
to: Samin Guo <samin.guo@...rfivetech.com>
data: 2023/4/26

> On Wed, Apr 26, 2023 at 02:35:40PM +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@...rfivetech.com>
>> ---
>>  .../devicetree/bindings/net/motorcomm,yt8xxx.yaml      | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/net/motorcomm,yt8xxx.yaml b/Documentation/devicetree/bindings/net/motorcomm,yt8xxx.yaml
>> index 157e3bbcaf6f..e648e486b6d8 100644
>> --- a/Documentation/devicetree/bindings/net/motorcomm,yt8xxx.yaml
>> +++ b/Documentation/devicetree/bindings/net/motorcomm,yt8xxx.yaml
>> @@ -18,6 +18,16 @@ properties:
>>        - ethernet-phy-id4f51.e91a
>>        - ethernet-phy-id4f51.e91b
>>  
>> +  rx-clk-driver-strength:
>> +    description: drive strength of rx_clk pad.
>> +    enum: [ 0, 1, 2, 3, 4, 5, 6, 7 ]
>> +    default: 3
> 
> What do the numbers mean? What are the units? mA?
> 
>      Andrew

Hi Andrew,

They represent the gradient of the current, which should be the higher the value, the greater the current.
However, there is no exact current value to determine from YT8531 datasheet.
Probably Motorcomm @Frank.sea knows what it means.

Description: Drive strenght of rx_clk pad.
3'b111: strongest;
3'b000: weakest.
Default: 0x3


Best regards,
Samin