[PATCH net] net: mii: Check speed and duplex only when autoneg is off

[Anthony Pighin]

mii_ethtool_get_link_ksettings() reports SPEED_UNKNOWN while the link is
down. ethtool reads the current settings, changes the autoneg and
advertising fields, and writes the result back. When it does this to
enable autoneg on a port without link, mii_ethtool_set_link_ksettings()
rejects the unknown speed with -EINVAL. For example, on an ax88179_178a
USB adapter while the link is down:

  # ethtool -s eth0 autoneg on advertise 0x2f
  Cannot set new settings: Invalid argument
    not setting autoneg

pch_gbe_set_link_ksettings() already works around the same failure by
replacing an unknown speed with SPEED_1000 before it calls
mii_ethtool_set_link_ksettings().

The autoneg path uses only the advertising mask, so check speed and
duplex only when the link is forced.

Fixes: f6f2e946aa4d ("net: mii: Fix the Speed display when the network cable is not connected")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Anthony Pighin <anthony.pighin@xxxxxxxxx>
---
 drivers/net/mii.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/net/mii.c b/drivers/net/mii.c
index 37bc3131d31a..439444637537 100644
--- a/drivers/net/mii.c
+++ b/drivers/net/mii.c
@@ -333,12 +333,6 @@ int mii_ethtool_set_link_ksettings(struct mii_if_info *mii,
 	struct net_device *dev = mii->dev;
 	u32 speed = cmd->base.speed;
 
-	if (speed != SPEED_10 &&
-	    speed != SPEED_100 &&
-	    speed != SPEED_1000)
-		return -EINVAL;
-	if (cmd->base.duplex != DUPLEX_HALF && cmd->base.duplex != DUPLEX_FULL)
-		return -EINVAL;
 	if (cmd->base.port != PORT_MII)
 		return -EINVAL;
 	if (cmd->base.phy_address != mii->phy_id)
@@ -346,8 +340,19 @@ int mii_ethtool_set_link_ksettings(struct mii_if_info *mii,
 	if (cmd->base.autoneg != AUTONEG_DISABLE &&
 	    cmd->base.autoneg != AUTONEG_ENABLE)
 		return -EINVAL;
-	if ((speed == SPEED_1000) && (!mii->supports_gmii))
-		return -EINVAL;
+
+	/* Speed is SPEED_UNKNOWN while the link is down; autoneg ignores it */
+	if (cmd->base.autoneg == AUTONEG_DISABLE) {
+		if (speed != SPEED_10 &&
+		    speed != SPEED_100 &&
+		    speed != SPEED_1000)
+			return -EINVAL;
+		if (cmd->base.duplex != DUPLEX_HALF &&
+		    cmd->base.duplex != DUPLEX_FULL)
+			return -EINVAL;
+		if ((speed == SPEED_1000) && (!mii->supports_gmii))
+			return -EINVAL;
+	}
 
 	/* ignore supported, maxtxpkt, maxrxpkt */
 

base-commit: 19a227903e65c7a9c179156485660a4e017575fe
-- 
2.43.0