Re: [PATCH net-next v3 02/10] net: mvpp2: phylink support

From: Russell King - ARM Linux
Date: Fri Aug 31 2018 - 10:11:49 EST

On Fri, Aug 31, 2018 at 03:36:51PM +0200, Antoine Tenart wrote:
> With the above code remove one case did not worked anymore: when the
> port is configured as a fixed-link because the SFP cage can't be
> described and used (on the 7040-db and 8040-db boards). In such cases
> phylink is called, mac_config() is called, but link_up() is never
> called. I'm not sure this is actually an issue in phylink, but the PPv2
> driver should probably take care of this weird case itself (by calling
> explicitly link_up()). What do you think?

Fixed link should work:

- when a fixed link is configured, is set true.
- when phylink_start() is called, mac_config() will be called to do the
initial setup, and a resolve is triggered.
- phylink_resolve() will read the fixed link state, which in the case
of no GPIO, will inherit
- you will then see another mac_config() call.

Now what happens depends whether you've set the netdev's carrier state
in the driver - if you haven't, the netdev's carrier state should be
off. Since the state mismatches the (which will be
true), you will get a mac_link_up() call.

mvneta ensures this state by always calling netif_carrier_off() in
mvneta_open(), maybe that ought to be in phylink_start() as that's the
state that phylink expects when phylink_start() has been called. So,
maybe it's a phylink bug.

Can you see any down-sides to moving the netif_carrier_off() in
mvneta_open() to phylink_start() ?

RMK's Patch system:
FTTC broadband for 0.8mile line in suburbia: sync at 13.8Mbps down 630kbps up
According to 13Mbps down 490kbps up