net: dsa: sja1105: Don't check state->link in phylink_mac_config

It has been pointed out that PHYLINK can call mac_config only to update
the phy_interface_type and without knowing what the AN results are.

Experimentally, when this was observed to happen, state->link was also
unset, and therefore was used as a proxy to ignore this call. However it
is also suggested that state->link is undefined for this callback and
should not be relied upon.

So let the previously-dead codepath for SPEED_UNKNOWN be called, and
update the comment to make sure the MAC's behavior is sane.

Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index caebf76..da17360 100644 (file)
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -715,7 +715,13 @@ static int sja1105_adjust_port_config(struct sja1105_private *priv, int port,
 
        switch (speed_mbps) {
        case SPEED_UNKNOWN:
-               /* No speed update requested */
+               /* PHYLINK called sja1105_mac_config() to inform us about
+                * the state->interface, but AN has not completed and the
+                * speed is not yet valid. UM10944.pdf says that setting
+                * SJA1105_SPEED_AUTO at runtime disables the port, so that is
+                * ok for power consumption in case AN will never complete -
+                * otherwise PHYLINK should come back with a new update.
+                */
                speed = SJA1105_SPEED_AUTO;
                break;
        case SPEED_10:
@@ -766,9 +772,6 @@ static void sja1105_mac_config(struct dsa_switch *ds, int port,
 {
        struct sja1105_private *priv = ds->priv;
 
-       if (!state->link)
-               return;
-
        sja1105_adjust_port_config(priv, port, state->speed);
 }