linux-kernel - [PATCH net v5 4/4] net: phy: bcm54811: Fix the PHY initialization

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Message-ID: <20250701075015.2601518-5-kamilh@axis.com>
Date: Tue, 1 Jul 2025 09:50:15 +0200
From: Kamil Horák - 2N <kamilh@...s.com>
To: <florian.fainelli@...adcom.com>, <bcm-kernel-feedback-list@...adcom.com>,
	<andrew@...n.ch>, <hkallweit1@...il.com>, <linux@...linux.org.uk>,
	<davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <krzk+dt@...nel.org>, <conor+dt@...nel.org>
CC: <kamilh@...s.com>, <netdev@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <f.fainelli@...il.com>, <robh@...nel.org>,
	<andrew+netdev@...n.ch>, <horms@...nel.org>, <corbet@....net>,
	<linux-doc@...r.kernel.org>
Subject: [PATCH net v5 4/4] net: phy: bcm54811: Fix the PHY initialization

Reset the bit 12 in PHY's LRE Control register upon initialization.
According to the datasheet, this bit must be written to zero after
every device reset.

Fixes: 03ab6c244bb0 ("net: phy: bcm-phy-lib: Implement BroadR-Reach link modes")
Signed-off-by: Kamil Horák - 2N <kamilh@...s.com>
Reviewed-by: Florian Fainelli <florian.fainelli@...adcom.com>
---
 drivers/net/phy/broadcom.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/net/phy/broadcom.c b/drivers/net/phy/broadcom.c
index 8547983bd72f..a60e58ef90c4 100644
--- a/drivers/net/phy/broadcom.c
+++ b/drivers/net/phy/broadcom.c
@@ -667,7 +667,7 @@ static int bcm5481x_read_abilities(struct phy_device *phydev)
 {
 	struct device_node *np = phydev->mdio.dev.of_node;
 	struct bcm54xx_phy_priv *priv = phydev->priv;
-	int i, val, err;
+	int i, val, err, aneg;
 
 	for (i = 0; i < ARRAY_SIZE(bcm54811_linkmodes); i++)
 		linkmode_clear_bit(bcm54811_linkmodes[i], phydev->supported);
@@ -688,9 +688,19 @@ static int bcm5481x_read_abilities(struct phy_device *phydev)
 		if (val < 0)
 			return val;
 
+		/* BCM54811 is not capable of LDS but the corresponding bit
+		 * in LRESR is set to 1 and marked "Ignore" in the datasheet.
+		 * So we must read the bcm54811 as unable to auto-negotiate
+		 * in BroadR-Reach mode.
+		 */
+		if (BRCM_PHY_MODEL(phydev) == PHY_ID_BCM54811)
+			aneg = 0;
+		else
+			aneg = val & LRESR_LDSABILITY;
+
 		linkmode_mod_bit(ETHTOOL_LINK_MODE_Autoneg_BIT,
 				 phydev->supported,
-				 val & LRESR_LDSABILITY);
+				 aneg);
 		linkmode_mod_bit(ETHTOOL_LINK_MODE_100baseT1_Full_BIT,
 				 phydev->supported,
 				 val & LRESR_100_1PAIR);
@@ -747,8 +757,15 @@ static int bcm54811_config_aneg(struct phy_device *phydev)
 
 	/* Aneg firstly. */
 	if (priv->brr_mode) {
-		/* BCM54811 is only capable of autonegotiation in IEEE mode */
-		phydev->autoneg = 0;
+		/* BCM54811 is only capable of autonegotiation in IEEE mode.
+		 * In BroadR-Reach mode, disable the Long Distance Signaling,
+		 * the BRR mode autoneg as supported in other Broadcom PHYs.
+		 * This bit is marked as "Reserved" and "Default 1, must be
+		 *  written to 0 after every device reset" in the datasheet.
+		 */
+		ret = phy_modify(phydev, MII_BCM54XX_LRECR, LRECR_LDSEN, 0);
+		if (ret < 0)
+			return ret;
 		ret = bcm_config_lre_aneg(phydev, false);
 	} else {
 		ret = genphy_config_aneg(phydev);
-- 
2.39.5