net: phy: phylink: fix DSA mac_select_pcs() introduction

Vladimir Oltean reports that probing on DSA drivers that aren't yet
populating supported_interfaces now fails. Fix this by allowing
phylink to detect whether DSA actually provides an underlying
mac_select_pcs() implementation.

Reported-by: Vladimir Oltean <olteanv@gmail.com>
Fixes: bde018222c6b ("net: dsa: add support for phylink mac_select_pcs()")
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Tested-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/E1nMCD6-00A0wC-FG@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 26f1219..28aa235 100644 (file)
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -74,6 +74,7 @@ struct phylink {
        struct work_struct resolve;
 
        bool mac_link_dropped;
+       bool using_mac_select_pcs;
 
        struct sfp_bus *sfp_bus;
        bool sfp_may_have_phy;
@@ -416,7 +417,7 @@ static int phylink_validate_mac_and_pcs(struct phylink *pl,
        int ret;
 
        /* Get the PCS for this interface mode */
-       if (pl->mac_ops->mac_select_pcs) {
+       if (pl->using_mac_select_pcs) {
                pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
                if (IS_ERR(pcs))
                        return PTR_ERR(pcs);
@@ -791,7 +792,7 @@ static void phylink_major_config(struct phylink *pl, bool restart,
 
        phylink_dbg(pl, "major config %s\n", phy_modes(state->interface));
 
-       if (pl->mac_ops->mac_select_pcs) {
+       if (pl->using_mac_select_pcs) {
                pcs = pl->mac_ops->mac_select_pcs(pl->config, state->interface);
                if (IS_ERR(pcs)) {
                        phylink_err(pl,
@@ -1205,11 +1206,17 @@ struct phylink *phylink_create(struct phylink_config *config,
                               phy_interface_t iface,
                               const struct phylink_mac_ops *mac_ops)
 {
+       bool using_mac_select_pcs = false;
        struct phylink *pl;
        int ret;
 
-       /* Validate the supplied configuration */
        if (mac_ops->mac_select_pcs &&
+           mac_ops->mac_select_pcs(config, PHY_INTERFACE_MODE_NA) !=
+             ERR_PTR(-EOPNOTSUPP))
+               using_mac_select_pcs = true;
+
+       /* Validate the supplied configuration */
+       if (using_mac_select_pcs &&
            phy_interface_empty(config->supported_interfaces)) {
                dev_err(config->dev,
                        "phylink: error: empty supported_interfaces but mac_select_pcs() method present\n");
@@ -1233,6 +1240,7 @@ struct phylink *phylink_create(struct phylink_config *config,
                return ERR_PTR(-EINVAL);
        }
 
+       pl->using_mac_select_pcs = using_mac_select_pcs;
        pl->phy_state.interface = iface;
        pl->link_interface = iface;
        if (iface == PHY_INTERFACE_MODE_MOCA)

diff --git a/net/dsa/port.c b/net/dsa/port.c
index 258782b..367d141 100644 (file)
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -1058,8 +1058,8 @@ dsa_port_phylink_mac_select_pcs(struct phylink_config *config,
                                phy_interface_t interface)
 {
        struct dsa_port *dp = container_of(config, struct dsa_port, pl_config);
+       struct phylink_pcs *pcs = ERR_PTR(-EOPNOTSUPP);
        struct dsa_switch *ds = dp->ds;
-       struct phylink_pcs *pcs = NULL;
 
        if (ds->ops->phylink_mac_select_pcs)
                pcs = ds->ops->phylink_mac_select_pcs(ds, dp->index, interface);