[PATCH v2 3/3] dt-bindings: phy: realtek: Add the doc about the Realtek SoC USB 2.0/3.0 PHY

[Conor Dooley]

On Thu, Jun 01, 2023 at 02:24:28AM +0000, Stanley Chang[昌育德] wrote:
> Hi Conor,
> 
> > > > You have device-specific compatibles, which is great, but you also allow
> > > > only those two generic ones. I had a _brief_ look at the driver, and it
> > > > seems like there is no decision making done based on the compatibles,
> > > > only on the properties. Is that correct?
> > > > If it is, I would understand having "realtek,usb3phy" as a fallback
> > > > compatible for "realtek,rtd1619-usb3phy", but I do not get the current
> > > > setup.
> > >
> > > This driver is compatible with all Realtek RTD SoCs without specifying different settings.
> > > So use "realtek,usb3phy" as fallback compatible for all SoCs.
> > > This is the compatible name we use.
> > > Other compatible names simply indicate that the driver supports the SoCs.
> > 
> > Then you should write the binding such that having fallback compatibles
> > is permitted. Try plugging
> > compatible = "realtek,rtd1295-usb2phy", "realtek,rtd-usb2phy", "realtek,usb2phy";
> > into your example below and see what happens.
> > 
> > > The name "usbNphy" and "rtd-usbNphy" seem to be more generic for all RTD SoCs,
> > > but they are not device-specific compatible.
> > > Do you have a better suggestion?
> > 
> > Write the binding so that having fallback compatibles in the DT actually
> > works, don't add the SoC-specific ones merely as indicators that those
> > SoCs are supported and don't permit "realtek,usbNphy" or
> > "realtek,rtd-usbNphy" in isolation ;)
> >
> 
> As far as I understand what you mean.
> I should follow other docs to define compatible.
> Reference:
>   Documentation/devicetree/bindings/phy/mediatek,xsphy.yaml
>   drivers/phy/mediatek/phy-mtk-xsphy.c
> 
> For example:
> 
>   compatible:
>     items:
>       - enum:
>           - realtek,rtd1295-usb2phy
>           - realtek,rtd1395-usb2phy
>           - realtek,rtd1619-usb2phy
>           - realtek,rtd1319-usb2phy
>           - realtek,rtd1619b-usb2phy
>           - realtek,rtd1312c-usb2phy
>           - realtek,rtd1319d-usb2phy
>           - realtek,rtd1315e-usb2phy
>       - const: realtek,usb2phy
> 
> examples:
>   -
>     dwc3_u3drd_usb2phy: dwc3_u3drd_usb2phy at 98013e14 {
>         compatible = "realtek,rtd1319-usb2phy", "realtek,usb2phy";
>   
> And use only "Realtek, usb2phy" in the driver.
> static const struct of_device_id usbphy_rtk_dt_match[] = {
>         { .compatible = "realtek,usb2phy", },
>         {},
> };

Yes, this would be a vast improvement, thanks.
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