RE: [EXT] Re: [PATCH 2/3] dt-bindings: usb: ci-hdrc-usb2: add samsung,picophy-rise-fall-time-adjust property

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Hi Krzysztof,

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> Sent: Monday, June 26, 2023 11:45 PM
> To: Xu Yang <xu.yang_2@xxxxxxx>; peter.chen@xxxxxxxxxx; robh+dt@xxxxxxxxxx; krzysztof.kozlowski+dt@xxxxxxxxxx;
> gregkh@xxxxxxxxxxxxxxxxxxx
> Cc: conor+dt@xxxxxxxxxx; shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>; Peng Fan
> <peng.fan@xxxxxxx>; linux-usb@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; Jun Li <jun.li@xxxxxxx>
> Subject: [EXT] Re: [PATCH 2/3] dt-bindings: usb: ci-hdrc-usb2: add samsung,picophy-rise-fall-time-adjust property
> 
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> 
> On 26/06/2023 11:29, Xu Yang wrote:
> > The samsung,picophy-rise-fall-time-adjust property can help to adjust the
> > rise/fall times of the high-speed transmitter waveform. The value can be
> > 0~3.
> >
> > Signed-off-by: Xu Yang <xu.yang_2@xxxxxxx>
> > ---
> >  .../devicetree/bindings/usb/ci-hdrc-usb2.yaml          | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.yaml b/Documentation/devicetree/bindings/usb/ci-
> hdrc-usb2.yaml
> > index 782402800d4a..d84c66c342ac 100644
> > --- a/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.yaml
> > +++ b/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.yaml
> > @@ -292,6 +292,16 @@ properties:
> >      minimum: 0x0
> >      maximum: 0xf
> >
> > +  samsung,picophy-rise-fall-time-adjust:
> > +    description:
> > +      HS Transmitter Rise/Fall Time Adjustment. Adjust the rise/fall times
> 
> Adjust with/by what? What are the units?

This property is used to adjust the rise/fall time of the high-speed
transmitter waveform. It has no unit. According to the description of
USBNC_n_PHY_CFG1 register, the rise/fall time will be increased or
decreased by a certain percentage relative to design default time if
a value is given to this property.

The actions as below:
  - 0: -10%
  - 1: design default 
  - 2: +15%
  - 3: +20%

> 
> > +      of the high-speed transmitter waveform. The range is from 0x0 to 0x3,
> > +      the default value is 0x1. Details can refer to TXRISETUNE0 bit of
> 
> default: 1
> 
> Don't repeat constraints in free form text.

Okay, will remove.

> 
> > +      USBNC_n_PHY_CFG1.
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    minimum: 0x0
> > +    maximum: 0x3
> 
> Why "samsung" prefix? If this is specific to samsung, make it
> specific/narrowed like other properties.
> 
> There are no Samsung compatibles here, so what is exactly here made by
> Samsung? Which device?

Reviewed the design, this is not specific to samsung. I will rename it to
fsl,picophy-rise-fall-time-adjust since it's related to imx chip.

Thanks,
Xu Yang

> 
> Best regards,
> Krzysztof





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