Re: [PATCH v2 1/3] dt-bindings: phy: imx8mq-usb: improve some tuning properties

[Conor Dooley <conor@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 4606 bytes --]

On Tue, Apr 29, 2025 at 11:30:07AM +0800, Xu Yang wrote:
> Commit b2e75563dc39 ("dt-bindings: phy: imx8mq-usb: add phy tuning
> properties") add many tuning properties, but some parameter value doesn't
> match the register description. It made some changes based on the original
> value: add offset to a negative number so turn it to a non-negative number.
> However, it's not easy to find an exact tuning value from register field
> with such conversion.
> 
> Because device-tree supports negative parameter number, this will improve
> some propertie's parameter.
> 
> Mainly include below properties:
>  - fsl,phy-tx-vref-tune-percent
>  - fsl,phy-tx-rise-tune-percent
>  - fsl,phy-comp-dis-tune-percent
> 
> The parameter value of above 3 properties are USB PHY specific. i.MX8MP
> and i.MX95 USB PHY has different meanings. So this add restrictions for
> them.

It's hard for me to understand from this if you're actually changing the
meaning of the property. Will the current/old values continue to
function as they have been?

> 
>  - fsl,phy-tx-vboost-level-microvolt
> 
> For this property, the parameter value is wrong in register description.
> This will correct it according to true value.
> 
> For detailed info, please refer to i.MX8MP and i.MX95 latest reference
> manual.
> 
> Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
> 
> ---
> Changes in v2:
>  - keep widest constraints
>  - use multipleOf for some properties
> ---
>  .../bindings/phy/fsl,imx8mq-usb-phy.yaml      | 60 +++++++++++++++----
>  1 file changed, 49 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/phy/fsl,imx8mq-usb-phy.yaml b/Documentation/devicetree/bindings/phy/fsl,imx8mq-usb-phy.yaml
> index daee0c0fc915..71e5940ef4b8 100644
> --- a/Documentation/devicetree/bindings/phy/fsl,imx8mq-usb-phy.yaml
> +++ b/Documentation/devicetree/bindings/phy/fsl,imx8mq-usb-phy.yaml
> @@ -42,16 +42,17 @@ properties:
>  
>    fsl,phy-tx-vref-tune-percent:
>      description:
> -      Tunes the HS DC level relative to the nominal level
> -    minimum: 94
> -    maximum: 124
> +      Tunes the HS DC level relative to the nominal level. It varies
> +      between different PHY versions
> +    minimum: -1000
> +    maximum: 875
>  
>    fsl,phy-tx-rise-tune-percent:
>      description:
>        Adjusts the rise/fall time duration of the HS waveform relative to
> -      its nominal value
> -    minimum: 97
> -    maximum: 103
> +      its nominal value. It varies between different PHY versions
> +    minimum: -10
> +    maximum: 20
>  
>    fsl,phy-tx-preemp-amp-tune-microamp:
>      description:
> @@ -63,15 +64,14 @@ properties:
>    fsl,phy-tx-vboost-level-microvolt:
>      description:
>        Adjust the boosted transmit launch pk-pk differential amplitude
> -    minimum: 880
> -    maximum: 1120
> +    enum: [844, 1008, 1156]
>  
>    fsl,phy-comp-dis-tune-percent:
>      description:
>        Adjust the voltage level used to detect a disconnect event at the host
> -      relative to the nominal value
> -    minimum: 91
> -    maximum: 115
> +      relative to the nominal value. It varies between different PHY versions
> +    minimum: -60
> +    maximum: 45
>  
>    fsl,phy-pcs-tx-deemph-3p5db-attenuation-db:
>      description:
> @@ -112,6 +112,44 @@ allOf:
>          reg:
>            maxItems: 1
>  
> +  - if:
> +      properties:
> +        compatible:
> +          enum:
> +            - fsl,imx8mq-usb-phy
> +            - fsl,imx8mp-usb-phy
> +    then:
> +      properties:
> +        fsl,phy-tx-vref-tune-percent:
> +          minimum: -6
> +          maximum: 24
> +          multipleOf: 2
> +        fsl,phy-tx-rise-tune-percent:
> +          enum: [-3, -1, 0, 3]
> +        fsl,phy-comp-dis-tune-percent:
> +          enum: [-9, -6, -3, 0, 4, 7, 11, 15]
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - fsl,imx95-usb-phy
> +    then:
> +      properties:
> +        fsl,phy-tx-vref-tune-percent:
> +          description: 100x the original
> +          minimum: -1000
> +          maximum: 875
> +          multipleOf: 125
> +        fsl,phy-tx-rise-tune-percent:
> +          enum: [-10, 0, 15, 20]
> +        fsl,phy-comp-dis-tune-percent:
> +          description: 10x the original
> +          minimum: -60
> +          maximum: 45
> +          multipleOf: 15
> +
>    - if:
>        required:
>          - orientation-switch
> -- 
> 2.34.1
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]