[PATCH v3 1/6] net: introduce DSA class for Ethernet switches

[Vladimir Oltean]

On Tue, 3 Dec 2019 at 17:32, Alex Marginean <alexandru.marginean at nxp.com> wrote:
> +/**
> + * This function deals with additional devices around the switch as these should
> + * have been bound to drivers by now.
> + * TODO: pick up references to other switch devices here, if we're cascaded.
> + */
> +static int dm_dsa_pre_probe(struct udevice *dev)
> +{
> +       struct dsa_perdev_platdata *platdata = dev_get_platdata(dev);
> +       int i;
> +
> +       if (!platdata)
> +               return -EINVAL;
> +
> +       if (ofnode_valid(platdata->master_node))
> +               uclass_find_device_by_ofnode(UCLASS_ETH, platdata->master_node,
> +                                            &platdata->master_dev);
> +
> +       for (i = 0; i < platdata->num_ports; i++) {
> +               struct dsa_port_platdata *port = &platdata->port[i];
> +
> +               if (port->dev) {
> +                       port->dev->priv = port;
> +                       port->phy = dm_eth_phy_connect(port->dev);

Fixed-link interfaces don't work with DM_MDIO. That is somewhat
natural as there is no MDIO bus for a fixed-link. However the legacy
phy_connect function can be made rather easily to work with
fixed-link, since it has the necessary code for dealing with it
already. I am not, however, sure how it ever worked in the absence of
an MDIO bus.

commit 1b7e23cc7e6d0dc3fe7ae9c55390b40717ff3c3a
Author: Vladimir Oltean <olteanv at gmail.com>
Date:   Sat Dec 14 23:25:40 2019 +0200

    phy: make phy_connect_fixed work with a null mdio bus

    It is utterly pointless to require an MDIO bus pointer for a fixed PHY
    device. The fixed.c implementation does not require it, only
    phy_device_create. Fix that.

    Signed-off-by: Vladimir Oltean <olteanv at gmail.com>

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 80a7664e4978..8ea5c9005291 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -658,7 +658,7 @@ static struct phy_device *phy_device_create(struct
mii_dev *bus, int addr,
        dev = malloc(sizeof(*dev));
        if (!dev) {
                printf("Failed to allocate PHY device for %s:%d\n",
-                      bus->name, addr);
+                      bus ? bus->name : "(null bus)", addr);
                return NULL;
        }

@@ -686,7 +686,7 @@ static struct phy_device *phy_device_create(struct
mii_dev *bus, int addr,
                return NULL;
        }

-       if (addr >= 0 && addr < PHY_MAX_ADDR)
+       if (addr >= 0 && addr < PHY_MAX_ADDR && phy_id != PHY_FIXED_ID)
                bus->phymap[addr] = dev;

        return dev;

With the patch above in place, fixed-link can also be made to work
with some logic similar to what can be seen below:

    if (ofnode_valid(ofnode_find_subnode(port->dev->node, "fixed-link")))
        port->phy = phy_connect(NULL, 0, port->dev, phy_mode); //
phy_mode needs to be pre-parsed somewhere else as well
    else
        port->phy = dm_eth_phy_connect(port->dev);

How would you see fixed-link interfaces being treated? My question so
far is in the context of front-panel ports but I am interested in your
view of the CPU port situation as well.

> +               }
> +       }
> +
> +       return 0;
> +}

Thanks,
-Vladimir