Re: [PATCH 1/2] dt-bindings: phy: imx8mq-usb: add phy tuning properties

[Johannes Zink]

Hi Krysztof,

thanks for your review, please find my questions below.

On Wed, 2023-04-05 at 13:51 +0200, Krzysztof Kozlowski wrote:
> [snip]
> >        A phandle to the regulator for USB VBUS.
> >  
> > +  fsl,phy-tx-vref-tune:
> > +    description:
> > +      HS DC Voltage level adjustment
> 
> "Level" in what units?
> 

The datasheet just shows percent, ranging from -6 to +24%, in 2%
increments. What unit would you suggest?

> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    enum: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
> > 16]
> > +
> > +  fsl,phy-tx-rise-tune:
> > +    description:
> > +      HS Transmitter Rise/Fall Time Adjustment
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    enum: [0, 1, 2, 3]
> > +
> > +  fsl,phy-tx-preemp-amp-tune:
> > +    description:
> > +      HS Transmitter Pre-Emphasis Current Control
> 
> If this is current then use standard unit suffixes.

According to the datasheet this is in "unit amonts" of 600uA, basically
0x600uA, 1x600uA etc. Should I just suffix it with uA then?

> 
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    enum: [0, 1, 2, 3]
> > +
> > +  fsl,phy-tx-vboost-level:
> > +    description:
> > +      TX Voltage Boost Level
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    enum: [0, 2, 3]
> > +
> > +  fsl,phy-comp-dis-tune:
> > +    description:
> > +      Disconnect Threshold Adjustment
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    enum: [0, 1, 2, 3, 4, 5, 6, 7]
> > +
> > +  fsl,phy-pcs-tx-deemph-3p5db:
> > +    description:
> > +      TX De-Emphasis at 3.5 dB
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +
> > +  fsl,phy-pcs-tx-swing-full:
> > +    description:
> > +      TX Amplitude
> 
> I have feeling you just pasted here short titles from datasheet. They
> are not that helpful.

ack, I will add some more text from the register description, since I
have no other source of information on these.

Best regards
Johannes

> 
> 
> 
> Best regards,
> Krzysztof
> 
> 
> 

-- 
Pengutronix e.K.                | Johannes Zink                  |
Steuerwalder Str. 21            | https://www.pengutronix.de/    |
31137 Hildesheim, Germany       | Phone: +49-5121-206917-0       |
Amtsgericht Hildesheim, HRA 2686| Fax:   +49-5121-206917-5555    |