Re: [PATCH v4 3/4] dt-bindings: net: xilinx_axienet: add pcs-handle attribute

[Rob Herring <robh@kernel.org>]

On Mon, Mar 21, 2022 at 03:42:52PM +0000, Radhey Shyam Pandey wrote:
> > -----Original Message-----
> > From: Andy Chiu <andy.chiu@sifive.com>
> > Sent: Monday, March 21, 2022 8:55 PM
> > To: Radhey Shyam Pandey <radheys@xilinx.com>; robert.hancock@calian.com;
> > Michal Simek <michals@xilinx.com>
> > Cc: davem@davemloft.net; kuba@kernel.org; pabeni@redhat.com;
> > robh+dt@kernel.org; linux@armlinux.org.uk; andrew@lunn.ch;
> > netdev@vger.kernel.org; devicetree@vger.kernel.org; Andy Chiu
> > <andy.chiu@sifive.com>; Greentime Hu <greentime.hu@sifive.com>
> > Subject: [PATCH v4 3/4] dt-bindings: net: xilinx_axienet: add pcs-handle
> > attribute
> > 
> > Document the new pcs-handle attribute to support connecting to an external
> > PHY in SGMII or 1000Base-X modes through the internal PCS/PMA PHY.
> > 
> > Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
> > Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
> > ---
> >  Documentation/devicetree/bindings/net/xilinx_axienet.txt | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/net/xilinx_axienet.txt
> > b/Documentation/devicetree/bindings/net/xilinx_axienet.txt
> > index b8e4894bc634..ba720a2ea5fc 100644
> > --- a/Documentation/devicetree/bindings/net/xilinx_axienet.txt
> > +++ b/Documentation/devicetree/bindings/net/xilinx_axienet.txt
> > @@ -26,7 +26,8 @@ Required properties:
> >  		  specified, the TX/RX DMA interrupts should be on that node
> >  		  instead, and only the Ethernet core interrupt is optionally
> >  		  specified here.
> > -- phy-handle	: Should point to the external phy device.
> > +- phy-handle	: Should point to the external phy device if exists. Pointing
> > +		  this to the PCS/PMA PHY is deprecated and should be
> > avoided.
> >  		  See ethernet.txt file in the same directory.
> >  - xlnx,rxmem	: Set to allocated memory buffer for Rx/Tx in the hardware
> > 
> > @@ -68,6 +69,11 @@ Optional properties:
> >  		  required through the core's MDIO interface (i.e. always,
> >  		  unless the PHY is accessed through a different bus).
> > 
> > + - pcs-handle: 	  Phandle to the internal PCS/PMA PHY in SGMII or 1000Base-X
> > +		  modes, where "pcs-handle" should be preferably used to
> > point
> > +		  to the PCS/PMA PHY, and "phy-handle" should point to an
> > +		  external PHY if exists.
> 
> I would like to have Rob feedback on this pcs-handle DT property.
> 
> The use case is generic i.e. require separate handle to internal SGMII
> and external Phy so would prefer this new DT convention is 
> standardized or we discuss possible approaches on how to handle
> both phys and not add it as vendor specific property in the first 
> place.

IMO, you should use 'phys' for the internal PCS phy. That's aligned with 
other uses like PCIe, SATA, etc. (there is phy h/w that will do PCS, 
PCIe, SATA). 'phy-handle' is for the ethernet PHY.

Rob