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

[Alexandru Marginean <alexm.osslist@gmail.com>]

On 12/15/2019 2:08 PM, Vladimir Oltean wrote:
> On Tue, 3 Dec 2019 at 17:32, Alex Marginean <alexandru.marginean@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@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@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.

I was thinking turning dm_eth_phy_connect into a more generic helper 
that also deals with fixed links, which it does not yet.  That would 
move the "fixed-link" if out of the driver code.  Ideally the driver 
should be able to call a single helper and, if the device has a DT node, 
it would get back a PHY handle to either a proper PHY or to a fixed link 
(from phy_connect_fixed).

Alex

> 
>> +               }
>> +       }
>> +
>> +       return 0;
>> +}
> 
> Thanks,
> -Vladimir
>