net: phy: dp83822: use BMCR_ANENABLE instead of BMSR_ANEGCAPABLE for DP83620

DP83620 register set is compatible with the DP83848, but it also supports
100base-FX. When the hardware is configured such as that fiber mode is
enabled, autonegotiation is not possible.

The chip, however, doesn't expose this information via BMSR_ANEGCAPABLE.
Instead, this bit is always set high, even if the particular hardware
configuration makes it so that auto negotiation is not possible [1]. Under
these circumstances, the phy subsystem keeps trying for autonegotiation to
happen, without success.

Hereby, we inspect BMCR_ANENABLE bit after genphy_config_init, which on
reset is set to 0 when auto negotiation is disabled, and so we use this
value instead of BMSR_ANEGCAPABLE.

[1] https://e2e.ti.com/support/interface/ethernet/f/903/p/697165/2571170

Signed-off-by: Alvaro Gamez Machado <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: agamez

drivers/net/phy/dp83848.c

@@ -74,6 +74,25 @@ static int dp83848_config_intr(struct phy_device *phydev)
 	return phy_write(phydev, DP83848_MICR, control);
 }
 
+static int dp83848_config_init(struct phy_device *phydev)
+{
+	int err;
+	int val;
+
+	err = genphy_config_init(phydev);
+	if (err < 0)
+		return err;
+
+	/* DP83620 always reports Auto Negotiation Ability on BMSR. Instead,
+	 * we check initial value of BMCR Auto negotiation enable bit
+	 */
+	val = phy_read(phydev, MII_BMCR);
+	if (!(val & BMCR_ANENABLE))
+		phydev->autoneg = AUTONEG_DISABLE;
+
+	return 0;
+}
+
 static struct mdio_device_id __maybe_unused dp83848_tbl[] = {
 	{ TI_DP83848C_PHY_ID, 0xfffffff0 },
 	{ NS_DP83848C_PHY_ID, 0xfffffff0 },
@@ -83,7 +102,7 @@ static struct mdio_device_id __maybe_unused dp83848_tbl[] = {
 };
 MODULE_DEVICE_TABLE(mdio, dp83848_tbl);
 
-#define DP83848_PHY_DRIVER(_id, _name)				\
+#define DP83848_PHY_DRIVER(_id, _name, _config_init)		\
 	{							\
 		.phy_id		= _id,				\
 		.phy_id_mask	= 0xfffffff0,			\
@@ -92,7 +111,7 @@ MODULE_DEVICE_TABLE(mdio, dp83848_tbl);
 		.flags		= PHY_HAS_INTERRUPT,		\
 								\
 		.soft_reset	= genphy_soft_reset,		\
-		.config_init	= genphy_config_init,		\
+		.config_init	= _config_init,			\
 		.suspend	= genphy_suspend,		\
 		.resume		= genphy_resume,		\
 								\
@@ -102,10 +121,14 @@ MODULE_DEVICE_TABLE(mdio, dp83848_tbl);
 	}
 
 static struct phy_driver dp83848_driver[] = {
-	DP83848_PHY_DRIVER(TI_DP83848C_PHY_ID, "TI DP83848C 10/100 Mbps PHY"),
-	DP83848_PHY_DRIVER(NS_DP83848C_PHY_ID, "NS DP83848C 10/100 Mbps PHY"),
-	DP83848_PHY_DRIVER(TI_DP83620_PHY_ID, "TI DP83620 10/100 Mbps PHY"),
-	DP83848_PHY_DRIVER(TLK10X_PHY_ID, "TI TLK10X 10/100 Mbps PHY"),
+	DP83848_PHY_DRIVER(TI_DP83848C_PHY_ID, "TI DP83848C 10/100 Mbps PHY",
+			   genphy_config_init),
+	DP83848_PHY_DRIVER(NS_DP83848C_PHY_ID, "NS DP83848C 10/100 Mbps PHY",
+			   genphy_config_init),
+	DP83848_PHY_DRIVER(TI_DP83620_PHY_ID, "TI DP83620 10/100 Mbps PHY",
+			   dp83848_config_init),
+	DP83848_PHY_DRIVER(TLK10X_PHY_ID, "TI TLK10X 10/100 Mbps PHY",
+			   genphy_config_init),
 };
 module_phy_driver(dp83848_driver);