Re: [PATCH 2/2] dt-bindings: net: dsa: qca8k: add internal-PHY-to-PHY CPU link example

[Andrew Lunn]

> (Port0 and Port6). Could I just keep this or should I need to add a new
> case ?

The existing examples are probably sufficient. Just check the text to
make sure it does not limit it to ports 0 and 6.

> > So is this actually internally? Or do you have a IPQ50xx SoC connected
> > to a qca8337 switch, with copper traces on a PCB? If so, it is not
> > internal.
> 
> The "internal" is used to describe the localcation of PHY not the link.
> In current code, qca8k has supported to use a external PHY to do a
> PHY-to-PHY link (Port0 and Port6). This patch make the internal PHYs
> support it too (Port1-5).
> 
> The followiing topology is existed in most IPQ50xx-based router:
>     _______________________         _______________________
>    |        IPQ5018        |       |        QCA8337        |
>    | +------+   +--------+ |       | +--------+   +------+ |
>    | | MAC0 |---| GE Phy |-+--MDI--+-|  Phy4  |---| MAC5 | |
>    | +------+   +--------+ |       | +--------+   +------+ |
>    | +------+   +--------+ |       | +--------+   +------+ |
>    | | MAC1 |---| Uniphy |-+-SGMII-+-| SerDes |---| MAC0 | |
>    | +------+   +--------+ |       | +--------+   +------+ |
>    |_______________________|       |_______________________|

So logically, it does not matter if the PHY is internal or
external. The patch would be the same. I've even see setups where the
SGMII link would have a PHY, then a connection to a daughter board,
and then a PHY back to SGMII before connecting to the switch. Running
Ethernet over the connector is easier than SERDES lines.

So i would probably drop the word internal from this discussion,
unless it is really relevant.

	Andrew