netdev - Re: [PATCH 1/3] dt-bindings: net: dp83826: add ti,cfg-dac-minus binding

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Message-ID: <a4af4a08-6eea-420b-b76f-47f4e836b476@leica-geosystems.com>
Date: Thu, 11 Jan 2024 16:45:26 +0000
From: POPESCU Catalin <catalin.popescu@...ca-geosystems.com>
To: Andrew Lunn <andrew@...n.ch>
CC: "davem@...emloft.net" <davem@...emloft.net>, "edumazet@...gle.com"
	<edumazet@...gle.com>, "kuba@...nel.org" <kuba@...nel.org>,
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	GEO-CHHER-bsp-development <bsp-development.geo@...ca-geosystems.com>
Subject: Re: [PATCH 1/3] dt-bindings: net: dp83826: add ti,cfg-dac-minus
 binding

On 11.01.24 17:35, Andrew Lunn wrote:
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> On Thu, Jan 11, 2024 at 05:19:25PM +0100, Catalin Popescu wrote:
>> Add property ti,cfg-dac-minus to allow for voltage tuning
>> of logical level -1 of the MLT-3 encoded data.
>>
>> Signed-off-by: Catalin Popescu <catalin.popescu@...ca-geosystems.com>
>> ---
>>   Documentation/devicetree/bindings/net/ti,dp83822.yaml | 9 +++++++++
>>   1 file changed, 9 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/net/ti,dp83822.yaml b/Documentation/devicetree/bindings/net/ti,dp83822.yaml
>> index db74474207ed..2f010333be49 100644
>> --- a/Documentation/devicetree/bindings/net/ti,dp83822.yaml
>> +++ b/Documentation/devicetree/bindings/net/ti,dp83822.yaml
>> @@ -62,6 +62,15 @@ properties:
>>          for the PHY.  The internal delay for the PHY is fixed to 3.5ns relative
>>          to transmit data.
>>
>> +  ti,cfg-dac-minus:
>> +    description: |
>> +       DP83826 PHY only.
>> +       Sets the voltage ratio of the logical level -1 for the MLT-3 encoded data.
>> +       0 = 50%, 1 = 56.25%, 2 = 62.50%, 3 = 68.75%, 4 = 75%, 5 = 81.25%, 6 = 87.50%,
>> +       7 = 93.75%, 8 = 100%, 9 = 106.25%, 10 = 112.50%, 11 = 118.75%, 12 = 125%,
>> +       13 = 131.25%, 14 = 137.50%, 15 = 143.75%, 16 = 150%.
>> +    enum: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]
> We try to avoid register values in DT. We use real units. This is a
> voltage you are configuring, so can you change the unit to millivolts?
> Have the driver do the conversion of volts to register value.
>
> Is it possible to configure any of the other logical levels?

Hi Andrew,
These are not raw register values and these are not voltage values but 
voltage ratios. I'm mapping the voltage ratios to enum values [0-16] 
which are converted to register raw values by the driver. I don't see a 
better way to do this.

>      Andrew
>
> ---
> pw-bot: cr