From: Vladimir Oltean vladimir.oltean@nxp.com
[ Upstream commit 4751d2aa321f2828d8c5d2f7ce4ed18a01e47f46 ]
stmmac_mdio_register() has logic to search for PHYs on the MDIO bus and assign them IRQ lines, as well as to set priv->plat->phy_addr.
If no PHY is found, the "found" variable remains set to 0 and the function errors out.
After the introduction of commit f213bbe8a9d6 ("net: stmmac: Integrate it with DesignWare XPCS"), the "found" variable was immediately reused for searching for a PCS on the same MDIO bus.
This can result in 2 types of potential problems (none of them seems to be seen on the only Intel system that sets has_xpcs = true, otherwise it would have been reported):
1. If a PCS is found but a PHY is not, then the code happily exits with no error. One might say "yes, but this is not possible, because of_mdiobus_register will probe a PHY for all MDIO addresses, including for the XPCS, so if an XPCS exists, then a PHY certainly exists too". Well, that is not true, see intel_mgbe_common_data():
/* Ensure mdio bus scan skips intel serdes and pcs-xpcs */ plat->mdio_bus_data->phy_mask = 1 << INTEL_MGBE_ADHOC_ADDR; plat->mdio_bus_data->phy_mask |= 1 << INTEL_MGBE_XPCS_ADDR;
2. A PHY is found but an MDIO device with the XPCS PHY ID isn't, and in that case, the error message will be "No PHY found". Confusing.
Signed-off-by: Vladimir Oltean vladimir.oltean@nxp.com Link: https://lore.kernel.org/r/20210527155959.3270478-1-olteanv@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- .../net/ethernet/stmicro/stmmac/stmmac_mdio.c | 21 +++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c index b2a707e2ef43..678726c62a8a 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c @@ -441,6 +441,12 @@ int stmmac_mdio_register(struct net_device *ndev) found = 1; }
+ if (!found && !mdio_node) { + dev_warn(dev, "No PHY found\n"); + err = -ENODEV; + goto no_phy_found; + } + /* Try to probe the XPCS by scanning all addresses. */ if (priv->hw->xpcs) { struct mdio_xpcs_args *xpcs = &priv->hw->xpcs_args; @@ -449,6 +455,7 @@ int stmmac_mdio_register(struct net_device *ndev)
xpcs->bus = new_bus;
+ found = 0; for (addr = 0; addr < max_addr; addr++) { xpcs->addr = addr;
@@ -458,13 +465,12 @@ int stmmac_mdio_register(struct net_device *ndev) break; } } - }
- if (!found && !mdio_node) { - dev_warn(dev, "No PHY found\n"); - mdiobus_unregister(new_bus); - mdiobus_free(new_bus); - return -ENODEV; + if (!found && !mdio_node) { + dev_warn(dev, "No XPCS found\n"); + err = -ENODEV; + goto no_xpcs_found; + } }
bus_register_done: @@ -472,6 +478,9 @@ bus_register_done:
return 0;
+no_xpcs_found: +no_phy_found: + mdiobus_unregister(new_bus); bus_register_fail: mdiobus_free(new_bus); return err;