Re: [RFC PATCH net-next 0/9] net: pcs: Add support for devices probed in the "usual" manner

[Vladimir Oltean]

Hi Sean,

On Mon, Jul 11, 2022 at 12:05:10PM -0400, Sean Anderson wrote:
> For a long time, PCSs have been tightly coupled with their MACs. For
> this reason, the MAC creates the "phy" or mdio device, and then passes
> it to the PCS to initialize. This has a few disadvantages:
> 
> - Each MAC must re-implement the same steps to look up/create a PCS
> - The PCS cannot use functions tied to device lifetime, such as devm_*.
> - Generally, the PCS does not have easy access to its device tree node
> 
> I'm not sure if these are terribly large disadvantages. In fact, I'm not
> sure if this series provides any benefit which could not be achieved
> with judicious use of helper functions. In any case, here it is.
> 
> NB: Several (later) patches in this series should not be applied. See
> the notes in each commit for details on when they can be applied.

Sorry to burst your bubble, but the networking drivers on NXP LS1028A
(device tree at arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi, drivers
at drivers/net/ethernet/freescale/enetc/ and drivers/net/dsa/ocelot/)
do not use the Lynx PCS through a pcs-handle, because the Lynx PCS in
fact has no backing OF node there, nor do the internal MDIO buses of the
ENETC and of the switch.

It seems that I need to point this out explicitly: you need to provide
at least a working migration path to your PCS driver model. Currently
there isn't one, and as a result, networking is broken on the LS1028A
with this patch set.