[PATCH v2 net-next] net: dsa: change PHY error message again

[Vladimir Oltean <olteanv@gmail.com>]

slave_dev->name is only populated at this stage if it was specified
through a label in the device tree. However that is not mandatory.
When it isn't, the error message looks like this:

[    5.037057] fsl_enetc 0000:00:00.2 eth2: error -19 setting up slave PHY for eth%d
[    5.044672] fsl_enetc 0000:00:00.2 eth2: error -19 setting up slave PHY for eth%d
[    5.052275] fsl_enetc 0000:00:00.2 eth2: error -19 setting up slave PHY for eth%d
[    5.059877] fsl_enetc 0000:00:00.2 eth2: error -19 setting up slave PHY for eth%d

which is especially confusing since the error gets printed on behalf of
the DSA master (fsl_enetc in this case).

Printing an error message that contains a valid reference to the DSA
port's name is difficult at this point in the initialization stage, so
at least we should print some info that is more reliable, even if less
user-friendly. That may be the driver name and the hardware port index.

After this change, the error is printed as:

[    6.051587] mscc_felix 0000:00:00.5: error -19 setting up PHY for tree 0, switch 0, port 0
[    6.061192] mscc_felix 0000:00:00.5: error -19 setting up PHY for tree 0, switch 0, port 1
[    6.070765] mscc_felix 0000:00:00.5: error -19 setting up PHY for tree 0, switch 0, port 2
[    6.080324] mscc_felix 0000:00:00.5: error -19 setting up PHY for tree 0, switch 0, port 3

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
---
The reason why I did not attempt to call dev_alloc_name() as Andrew
suggested:
https://patchwork.ozlabs.org/project/netdev/patch/20200823213520.2445615-1-olteanv@gmail.com/
is that, in the case of a persistent error, all interfaces would get the
same name, and this would create more confusion than it would solve.
Also, that interface name would appear in the kernel log exactly once,
because this is an error path and we're going to free it right away. So,
if a label is not in use, better not print anything.

[    6.051587] mscc_felix 0000:00:00.5: error -19 setting up PHY for tree 0, switch 0, port 0, name eth3
[    6.061192] mscc_felix 0000:00:00.5: error -19 setting up PHY for tree 0, switch 0, port 1, name eth3
[    6.070765] mscc_felix 0000:00:00.5: error -19 setting up PHY for tree 0, switch 0, port 2, name eth3
[    6.080324] mscc_felix 0000:00:00.5: error -19 setting up PHY for tree 0, switch 0, port 3, name eth3

 net/dsa/slave.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 9af1a2d0cec4..27931141d30f 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -1792,8 +1792,9 @@ int dsa_slave_create(struct dsa_port *port)
 
 	ret = dsa_slave_phy_setup(slave_dev);
 	if (ret) {
-		netdev_err(master, "error %d setting up slave PHY for %s\n",
-			   ret, slave_dev->name);
+		netdev_err(slave_dev,
+			   "error %d setting up PHY for tree %d, switch %d, port %d\n",
+			   ret, ds->dst->index, ds->index, port->index);
 		goto out_gcells;
 	}
 
-- 
2.25.1