Re: [PATCH net-next v9 04/10] net: phy: Create SFP phy_port before registering upstream

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Hi Andrew,

On 15/04/2026 01:46, Andrew Lunn wrote:
> On Fri, Apr 03, 2026 at 02:37:48PM +0200, Maxime Chevallier wrote:
>> When dealing with PHY-driven SFP, we create a phy_port representing the
>> SFP bus when we know we have such a bus.
> 
> I'm missing the big picture here.
> 
> Do we have three different things represented in the topology:
> 
> SFP bus-> SFP cage-> SFP module
> 
> 	Andrew

Ah by bad, this is a wording issue, this is the port for the cage indeed.

The model I ended-up with is to represent the SFP cage itself as a PHY
port, but I've been calling that the "sfp bus port" in the code so far :/

Let me try to summarize the phy_port usage, especially with SFP :


         phylink->sfp_bus_port (should be renamed sfp_cage_port)
          vacant = true
              |
              v
+-----+   +----------+
| MAC | - | SFP cage |
+-----+   +----------+


           phylink->sfp_bus_port, vacant = false
                |
                |             phylink->mod_port
                v                v
+-----+     +----------+     +------------+
| MAC | --- | SFP cage | --- | SFP Module |
+-----+     +----------+     +------------+


                    one of phydev->ports
                           v
+-----+     +-----+     +------+
| MAC | --- | PHY | --- | RJ45 |
+-----+     +-----+     +------+


                      one of phydev->ports
                             v
                          +------+
+-----+     +-----+   /-- | RJ45 |
| MAC | --- | PHY | -+    +------+
+-----+     |     | -+    +----------+
            +-----+   \-- | SFP Cage |
                          +----------+
                             ^
                      phydev->sfp_bus_port +
                   is also in phydev->ports
                     port->vacant = true


                      one of phydev->ports
                             v
                          +------+
+-----+     +-----+   /-- | RJ45 |         phydev->mod_port
| MAC | --- | PHY | -+    +------+              v
+-----+     |     | -+    +----------+     +------------+
            +-----+   \-- | SFP Cage | --- | SFP Module |
                          +----------+     +------------+
                             ^
                      phydev->sfp_bus_port +
                   is also in phydev->ports
                     port->vacant = false


I should probably add that at least in the cover. Does it clarify the
picture a little bit ?

Thanks a lot for the reviews :)

Maxime