net: phy: dp83869: fix status reporting for 1000base-x autonegotiation

The DP83869 PHY transceiver supports converting from RGMII to 1000base-x.
In this operation mode, autonegotiation can be performed, as described in
IEEE802.3.

The DP83869 has a set of fiber-specific registers located at offset 0xc00.
When the transceiver is configured in RGMII-to-1000base-x mode, these
registers are mapped onto offset 0, which should make reading the
autonegotiation status transparent.

However, the fiber registers at offset 0xc04 and 0xc05 follow the bit
layout specified in Clause 37, and genphy_read_status() assumes a Clause 22
layout. Thus, genphy_read_status() doesn't properly read the capabilities
advertised by the link partner, resulting in incorrect link parameters.

Similarly, genphy_config_aneg() doesn't properly write advertised
capabilities.

Fix the 1000base-x autonegotiation procedure by replacing
genphy_read_status() and genphy_config_aneg() with their Clause 37
equivalents.

Fixes: a29de52 ("net: dp83869: Add ability to advertise Fiber connection")
Cc: [email protected]
Signed-off-by: Romain Gantois <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: rgantois

drivers/net/phy/dp83869.c

@@ -153,19 +153,32 @@ struct dp83869_private {
 	int mode;
 };
 
+static int dp83869_config_aneg(struct phy_device *phydev)
+{
+	struct dp83869_private *dp83869 = phydev->priv;
+
+	if (dp83869->mode != DP83869_RGMII_1000_BASE)
+		return genphy_config_aneg(phydev);
+
+	return genphy_c37_config_aneg(phydev);
+}
+
 static int dp83869_read_status(struct phy_device *phydev)
 {
 	struct dp83869_private *dp83869 = phydev->priv;
+	bool changed;
 	int ret;
 
+	if (dp83869->mode == DP83869_RGMII_1000_BASE)
+		return genphy_c37_read_status(phydev, &changed);
+
 	ret = genphy_read_status(phydev);
 	if (ret)
 		return ret;
 
-	if (linkmode_test_bit(ETHTOOL_LINK_MODE_FIBRE_BIT, phydev->supported)) {
+	if (dp83869->mode == DP83869_RGMII_100_BASE) {
 		if (phydev->link) {
-			if (dp83869->mode == DP83869_RGMII_100_BASE)
-				phydev->speed = SPEED_100;
+			phydev->speed = SPEED_100;
 		} else {
 			phydev->speed = SPEED_UNKNOWN;
 			phydev->duplex = DUPLEX_UNKNOWN;
@@ -898,6 +911,7 @@ static int dp83869_phy_reset(struct phy_device *phydev)
 	.soft_reset	= dp83869_phy_reset,			\
 	.config_intr	= dp83869_config_intr,			\
 	.handle_interrupt = dp83869_handle_interrupt,		\
+	.config_aneg    = dp83869_config_aneg,                  \
 	.read_status	= dp83869_read_status,			\
 	.get_tunable	= dp83869_get_tunable,			\
 	.set_tunable	= dp83869_set_tunable,			\