RE: [PATCH v6 1/2] dt-bindings: net: Add FSD EQoS device tree bindings

["Swathi K S" <swathi.ks@samsung.com>]

> -----Original Message-----
> From: Andrew Lunn <andrew@lunn.ch>
> Sent: 17 February 2025 20:48
> To: Swathi K S <swathi.ks@samsung.com>
> Cc: krzk+dt@kernel.org; andrew+netdev@lunn.ch; davem@davemloft.net;
> edumazet@google.com; kuba@kernel.org; pabeni@redhat.com;
> robh@kernel.org; conor+dt@kernel.org; richardcochran@gmail.com;
> mcoquelin.stm32@gmail.com; alexandre.torgue@foss.st.com;
> rmk+kernel@armlinux.org.uk; netdev@vger.kernel.org;
> devicetree@vger.kernel.org; linux-stm32@st-md-mailman.stormreply.com;
> linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org;
'Pankaj
> Dubey' <pankaj.dubey@samsung.com>; ravi.patel@samsung.com
> Subject: Re: [PATCH v6 1/2] dt-bindings: net: Add FSD EQoS device tree
> bindings
> 
> > > > > > +  phy-mode:
> > > > > > +    enum:
> > > > > > +      - rgmii-id
> > > > >
> > > > > phy-mode is normally a board property, in the .dts file, since
> > > > > the board
> > > > might
> > > > > decide to have extra long clock lines and so want 'rgmii'.
> 
> > Hi Andrew,
> > What you said is right. Generally, PCB provides internal delay.
> 
> It is actually pretty unusual for the PCB to add the delays. But there are
some
> boards which do this. Which is why you should support it.
> 
> > But in this case, due to customer request, the delay was added into SoC.
> 
> Idealy, by the PHY. However, in terms of DT, the board .dts file just
needs to
> say 'rmgii-id', meaning that the board does not provide the delays, so the
> MAC/PHY pair needs to provide the delay.
> 
> > The following doc on rgmii says that "Devices which implement internal
> > delay shall be referred to as RGMII-ID.
> > Devices may offer an option to operate with/without internal delay and
> > still remain compliant with this spec"
> >
> https://community.nxp.com/pwmxy87654/attachments/pwmxy87654/imx-
> proces
> > sors/2
> > 0655/1/RGMIIv2_0_final_hp.pdf
> >
> > Also, the driver is in such a way that it handles all four rgmii in
> > the same way.
> >
> > Considering this, could you let us know what will be the right
> > approach to take in this case?
> 
> List all four phy-modes in the binding. They should all be valid. However,
the
> .dtsi file should not list a phy-mode, since it is a board property, not a
SoC
> property.

Hi Andrew, 
Thanks for the clarification.
Will post v7 with the following updates:

1. Changing phy-mode in dt-binding as shown below:
  phy-mode:
    enum:
      - rgmii
      - rgmii-id
      - rgmii-rxid
      - rgmii-txid
	  
2. Removing phy-mode from .dtsi and example given in dt-binding
3. Add phy-mode to .dts file and specify 'rgmii-id' there.

Hope this will address your review comment.

Thanks,
Swathi

> 
> 	Andrew