Re: [PATCH net] net: bcmgenet: Ensure MDIO unregistration has clocks enabled

[Andrew Lunn]

On Thu, Jun 22, 2023 at 03:31:07AM -0700, Florian Fainelli wrote:
> With support for Ethernet PHY LEDs having been added, while
> unregistering a MDIO bus and its child device liks PHYs there may be
> "late" accesses to the MDIO bus. One typical use case is setting the PHY
> LEDs brightness to OFF for instance.
> 
> We need to ensure that the MDIO bus controller remains entirely
> functional since it runs off the main GENET adapter clock.

So this clock is enabled in bcmgenet_open() and disabled in
bcmgenet_close(). The assumption being, the MDIO bus is only used when
the interface is up.

How does this work when there is an MDIO based switch attached? I had
similar problems with the FEC and mv88e6xxx. DSA would try to talk to
the switch with the master interface down, and MDIO would time out. I
needed to add runtime PM support to the MDIO bus ops.

       Andrew