Re: [PATCH v6 4/5] dt-bindings: phy: realtek: Add the doc about the Realtek SoC USB 2.0 PHY

Re: [PATCH v6 4/5] dt-bindings: phy: realtek: Add the doc about the Realtek SoC USB 2.0 PHY

[Rob Herring]

On Thu, Jun 29, 2023 at 01:45:12PM +0800, Stanley Chang wrote:
> Add the documentation explain the property about Realtek USB PHY driver.

In the subject, drop "the doc about the". It's redundant. And perhaps 
add 'DHC RTD SoC' if this isn't for *all* Realtek SoCs.

> Realtek DHC (digital home center) RTD SoCs support DWC3 XHCI USB
> controller. Added the driver to drive the USB 2.0 PHY transceivers.

driver? This is a binding for the h/w.

> 
> Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
> ---
> v5 to v6 change:
>     Drop the redundant examples
>     Drop the label of example
> v4 to v5 change:
>     1. Add more examples.
>     2. Remove the compatible realtek,usb2phy.
>     3. Revise the descriptor of the property.
>     4. Add the default of the property.
> v3 to v4 change:
>     1. Remove the parameter and non hardware properties from dts.
>     2. Using the compatible data included the config and parameter
>        in driver.
> v2 to v3 change:
>     1. Broken down into two patches, one for each of USB 2 & 3.
>     2. Add more description about Realtek RTD SoCs architecture.
>     3. Removed parameter v1 support for simplification.
>     4. Revised the compatible name for fallback compatible.
>     5. Remove some properties that can be set in the driver.
> v1 to v2 change:
>     Add phy-cells for generic phy driver
> ---
>  .../bindings/phy/realtek,usb2phy.yaml         | 153 ++++++++++++++++++
>  1 file changed, 153 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/phy/realtek,usb2phy.yaml
> 
> diff --git a/Documentation/devicetree/bindings/phy/realtek,usb2phy.yaml b/Documentation/devicetree/bindings/phy/realtek,usb2phy.yaml
> new file mode 100644
> index 000000000000..773663bf5c62
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/phy/realtek,usb2phy.yaml
> @@ -0,0 +1,153 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +# Copyright 2023 Realtek Semiconductor Corporation
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/phy/realtek,usb2phy.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Realtek DHC SoCs USB 2.0 PHY
> +
> +maintainers:
> +  - Stanley Chang <stanley_chang@realtek.com>
> +
> +description:

You need '|' if formatting (line breaks) are important.

> +  Realtek USB 2.0 PHY support the digital home center (DHC) RTD series SoCs.
> +  The USB 2.0 PHY driver is designed to support the XHCI controller. The SoCs
> +  support multiple XHCI controllers. One PHY device node maps to one XHCI
> +  controller.
> +
> +  RTD1295/RTD1619 SoCs USB
> +  The USB architecture includes three XHCI controllers.
> +  Each XHCI maps to one USB 2.0 PHY and map one USB 3.0 PHY on some
> +  controllers.
> +  XHCI controller#0 -- usb2phy -- phy#0
> +                    |- usb3phy -- phy#0
> +  XHCI controller#1 -- usb2phy -- phy#0
> +  XHCI controller#2 -- usb2phy -- phy#0
> +                    |- usb3phy -- phy#0
> +
> +  RTD1395 SoCs USB
> +  The USB architecture includes two XHCI controllers.
> +  The controller#0 has one USB 2.0 PHY. The controller#1 includes two USB 2.0
> +  PHY.
> +  XHCI controller#0 -- usb2phy -- phy#0
> +  XHCI controller#1 -- usb2phy -- phy#0
> +                               |- phy#1
> +
> +  RTD1319/RTD1619b SoCs USB
> +  The USB architecture includes three XHCI controllers.
> +  Each XHCI maps to one USB 2.0 PHY and map one USB 3.0 PHY on controllers#2.
> +  XHCI controller#0 -- usb2phy -- phy#0
> +  XHCI controller#1 -- usb2phy -- phy#0
> +  XHCI controller#2 -- usb2phy -- phy#0
> +                    |- usb3phy -- phy#0
> +
> +  RTD1319d SoCs USB
> +  The USB architecture includes three XHCI controllers.
> +  Each xhci maps to one USB 2.0 PHY and map one USB 3.0 PHY on controllers#0.
> +  XHCI controller#0 -- usb2phy -- phy#0
> +                    |- usb3phy -- phy#0
> +  XHCI controller#1 -- usb2phy -- phy#0
> +  XHCI controller#2 -- usb2phy -- phy#0
> +
> +  RTD1312c/RTD1315e SoCs USB
> +  The USB architecture includes three XHCI controllers.
> +  Each XHCI maps to one USB 2.0 PHY.
> +  XHCI controller#0 -- usb2phy -- phy#0
> +  XHCI controller#1 -- usb2phy -- phy#0
> +  XHCI controller#2 -- usb2phy -- phy#0
> +
> +properties:
> +  compatible:
> +    enum:
> +      - realtek,rtd1295-usb2phy
> +      - realtek,rtd1312c-usb2phy
> +      - realtek,rtd1315e-usb2phy
> +      - realtek,rtd1319-usb2phy
> +      - realtek,rtd1319d-usb2phy
> +      - realtek,rtd1395-usb2phy
> +      - realtek,rtd1395-usb2phy-2port
> +      - realtek,rtd1619-usb2phy
> +      - realtek,rtd1619b-usb2phy
> +
> +  reg:
> +    items:
> +      - description: PHY data registers
> +      - description: PHY control registers
> +
> +  "#phy-cells":
> +    const: 0
> +
> +  nvmem-cells:
> +    maxItems: 2
> +    description:
> +      Phandles to nvmem cell that contains the trimming data.
> +      If unspecified, default value is used.
> +
> +  nvmem-cell-names:
> +    items:
> +      - const: usb-dc-cal
> +      - const: usb-dc-dis
> +    description:
> +      The following names, which correspond to each nvmem-cells.
> +      usb-dc-cal is the driving level for each phy specified via efuse.
> +      usb-dc-dis is the disconnection level for each phy specified via efuse.
> +
> +  realtek,inverse-hstx-sync-clock:
> +    description:
> +      For one of the phys of RTD1619b SoC, the synchronous clock of the
> +      high-speed tx must be inverted.

"invert" assumes I know what non-inverted means. I do not. Better to 
state in terms of active high, low, falling edge, rising edge, etc.

> +    type: boolean
> +
> +  realtek,driving-level:
> +    description:
> +      Control the magnitude of High speed Dp/Dm output swing.
> +      For a different board or port, the original magnitude maybe not meet
> +      the specification. In this situation we can adjust the value to meet
> +      the specification.

What are the units?

> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    default: 8
> +    minimum: 0
> +    maximum: 31
> +
> +  realtek,driving-compensate:

compensate what?

> +    description:
> +      For RTD1315e SoC, the driving level can be adjusted by reading the
> +      efuse table. This property provides drive compensation.
> +      If the magnitude of High speed Dp/Dm output swing still not meet the
> +      specification, then we can set this value to meet the specification.
> +    $ref: /schemas/types.yaml#/definitions/int32
> +    default: 0
> +    minimum: -8
> +    maximum: 8
> +
> +  realtek,disconnection-compensate:
> +    description:
> +      This adjusts the disconnection level compensation for the different
> +      boards with different disconnection level.
> +    $ref: /schemas/types.yaml#/definitions/int32
> +    default: 0
> +    minimum: -8
> +    maximum: 8
> +
> +required:
> +  - compatible
> +  - reg
> +  - "#phy-cells"
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    usb-phy@13214 {
> +        compatible = "realtek,rtd1619b-usb2phy";
> +        reg = <0x13214 0x4>, <0x28280 0x4>;
> +        #phy-cells = <0>;
> +        nvmem-cells = <&otp_usb_port0_dc_cal>, <&otp_usb_port0_dc_dis>;
> +        nvmem-cell-names = "usb-dc-cal", "usb-dc-dis";
> +
> +        realtek,inverse-hstx-sync-clock;
> +        realtek,driving-level = <0xa>;
> +        realtek,driving-compensate = <(-1)>;
> +        realtek,disconnection-compensate = <(-1)>;
> +    };
> -- 
> 2.34.1
> 

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Re: [PATCH v6 4/5] dt-bindings: phy: realtek: Add the doc about the Realtek SoC USB 2.0 PHY

[Conor Dooley]

[-- Attachment #1.1: Type: text/plain, Size: 3334 bytes --]

On Fri, Jun 30, 2023 at 07:33:45AM +0000, Stanley Chang[昌育德] wrote:
> Hi Rob,
> 
> > On Thu, Jun 29, 2023 at 01:45:12PM +0800, Stanley Chang wrote:
> > > Add the documentation explain the property about Realtek USB PHY driver.
> > 
> > In the subject, drop "the doc about the". It's redundant. And perhaps add 'DHC
> > RTD SoC' if this isn't for *all* Realtek SoCs.
> > 
> > > Realtek DHC (digital home center) RTD SoCs support DWC3 XHCI USB
> > > controller. Added the driver to drive the USB 2.0 PHY transceivers.
> > 
> > driver? This is a binding for the h/w.
> 
> I mean, the driver is drivers/phy/realtek/phy-rtk-usb2.c
> I will revise as
>     dt-bindings: phy: realtek: Add the Realtek DHC RTD SoC USB 2.0 PHY
> 
>     Add the documentation explain the property about Realtek USB PHY driver.
> 
>     Realtek DHC (digital home center) RTD SoCs support DWC3 XHCI USB
>     controller and uses phy-rtk-usb2 as driver for USB 2.0 PHY transceiver..

No, you should mention nothing to do with how a particular operating
system chooses to structure its code here. Bindings describe hardware,
and the commit message should reflect that.

> 
> > > +$id: http://devicetree.org/schemas/phy/realtek,usb2phy.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Realtek DHC SoCs USB 2.0 PHY
> > > +
> > > +maintainers:
> > > +  - Stanley Chang <stanley_chang@realtek.com>
> > > +
> > > +description:
> > 
> > You need '|' if formatting (line breaks) are important.
> 
> I think I need it. I will add it.
> 
> > > +  realtek,inverse-hstx-sync-clock:
> > > +    description:
> > > +      For one of the phys of RTD1619b SoC, the synchronous clock of the
> > > +      high-speed tx must be inverted.
> > 
> > "invert" assumes I know what non-inverted means. I do not. Better to state in
> > terms of active high, low, falling edge, rising edge, etc.
> 
> Meaning, the clock must be reversed.

Maybe that means something to Rob, but "reversed" doesn't seem any more
meaningful than inverse. I agree that it should be described in terms of
"active high" etc, as they have well understood meanings.

> > > +    type: boolean
> > > +
> > > +  realtek,driving-level:
> > > +    description:
> > > +      Control the magnitude of High speed Dp/Dm output swing.
> > > +      For a different board or port, the original magnitude maybe not
> > meet
> > > +      the specification. In this situation we can adjust the value to meet
> > > +      the specification.
> > 
> > What are the units?
> 
> There is no unit. It is only a gain for adjusting the magnitude.

Gain has units too.

> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +    default: 8
> > > +    minimum: 0
> > > +    maximum: 31
> > > +
> > > +  realtek,driving-compensate:
> > 
> > compensate what?
> 
> It is to compensate the driving level.

Should it be called "driving-level-compensate" then?

> In other word, to adjust the driving level.

So, "realtek,driving-level" sets the gain and
"realtek,driving-compensate" adjusts the driving level.
By that logic, is this also a gain?

Also this property is only for the RTD1315e? That should be
described in/constrained by the binding itself, not in the text
description alone IMO.


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