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

Frank Li
2025-04-29T05:57:46Z

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

It should be standard unit. for example 0% to 100%. DT don't prefer you
direct use register value.

Frank

>
> 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.
>
> - 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
>