net: phy: at803x: add DAC amplitude fix for 8327 phy

QCA8327 internal phy require DAC amplitude adjustement set to +6% with
100m speed. Also add additional define to report a change of the same
reg in QCA8337. (different scope it does set 1000m voltage)
Add link_change_notify function to set the proper amplitude adjustement
on PHY_RUNNING state and disable on any other state.

Fixes: b4df02b562 ("net: phy: at803x: add support for qca 8327 A variant internal phy")
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/at803x.c

@@ -87,6 +87,8 @@
 #define AT803X_PSSR_MR_AN_COMPLETE		0x0200
 
 #define AT803X_DEBUG_REG_0			0x00
+#define QCA8327_DEBUG_MANU_CTRL_EN		BIT(2)
+#define QCA8337_DEBUG_MANU_CTRL_EN		GENMASK(3, 2)
 #define AT803X_DEBUG_RX_CLK_DLY_EN		BIT(15)
 
 #define AT803X_DEBUG_REG_5			0x05
@@ -1317,9 +1319,37 @@ static int qca83xx_config_init(struct phy_device *phydev)
 		break;
 	}
 
+	/* QCA8327 require DAC amplitude adjustment for 100m set to +6%.
+	 * Disable on init and enable only with 100m speed following
+	 * qca original source code.
+	 */
+	if (phydev->drv->phy_id == QCA8327_A_PHY_ID ||
+	    phydev->drv->phy_id == QCA8327_B_PHY_ID)
+		at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
+				      QCA8327_DEBUG_MANU_CTRL_EN, 0);
+
 	return 0;
 }
 
+static void qca83xx_link_change_notify(struct phy_device *phydev)
+{
+	/* QCA8337 doesn't require DAC Amplitude adjustement */
+	if (phydev->drv->phy_id == QCA8337_PHY_ID)
+		return;
+
+	/* Set DAC Amplitude adjustment to +6% for 100m on link running */
+	if (phydev->state == PHY_RUNNING) {
+		if (phydev->speed == SPEED_100)
+			at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
+					      QCA8327_DEBUG_MANU_CTRL_EN,
+					      QCA8327_DEBUG_MANU_CTRL_EN);
+	} else {
+		/* Reset DAC Amplitude adjustment */
+		at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_0,
+				      QCA8327_DEBUG_MANU_CTRL_EN, 0);
+	}
+}
+
 static int qca83xx_resume(struct phy_device *phydev)
 {
 	int ret, val;
@@ -1489,6 +1519,7 @@ static struct phy_driver at803x_driver[] = {
 	.phy_id_mask		= QCA8K_PHY_ID_MASK,
 	.name			= "Qualcomm Atheros 8337 internal PHY",
 	/* PHY_GBIT_FEATURES */
+	.link_change_notify	= qca83xx_link_change_notify,
 	.probe			= at803x_probe,
 	.flags			= PHY_IS_INTERNAL,
 	.config_init		= qca83xx_config_init,
@@ -1504,6 +1535,7 @@ static struct phy_driver at803x_driver[] = {
 	.phy_id_mask		= QCA8K_PHY_ID_MASK,
 	.name			= "Qualcomm Atheros 8327-A internal PHY",
 	/* PHY_GBIT_FEATURES */
+	.link_change_notify	= qca83xx_link_change_notify,
 	.probe			= at803x_probe,
 	.flags			= PHY_IS_INTERNAL,
 	.config_init		= qca83xx_config_init,
@@ -1519,6 +1551,7 @@ static struct phy_driver at803x_driver[] = {
 	.phy_id_mask		= QCA8K_PHY_ID_MASK,
 	.name			= "Qualcomm Atheros 8327-B internal PHY",
 	/* PHY_GBIT_FEATURES */
+	.link_change_notify	= qca83xx_link_change_notify,
 	.probe			= at803x_probe,
 	.flags			= PHY_IS_INTERNAL,
 	.config_init		= qca83xx_config_init,