Re: [PATCH net-next v2 4/6] net: mdio: scan bus based on bus capabilities for C22 and C45

[Klaus Kudielka]

On Sun, 2023-03-12 at 10:04 +0100, Klaus Kudielka wrote:
> On Sun, 2023-03-12 at 03:53 +0100, Andrew Lunn wrote:
> > 
> > Correct. But their also should not of been any noticeable slow down,
> > because there should not be any additional scanning when everything is
> > described in DT. And the move of the MDIO bus registration from probe
> > to setup should actually make it faster than before.
> > 
> 
> But then, why *do* I see such a big difference on the Omnia?
> 
> mdiobus_scan_bus_c45() takes:
> ~2.7 seconds without phy_mask patch
> ~0.2 seconds with phy_mask patch

Following up myself, the answer is in the call path
mv88e6xxx_mdios_register()
	 -> mv88e6xxx_mdio_register()
		-> of_mdiobus_register()

A child node "mdio" would be needed for the scan to be limited by
the device tree. And this one is *not* in armada-385-turris-omnia.dts.

My (incorrect) understanding was, the child node "ports" would trigger
that behaviour.

Best regards, Klaus