amd-xgbe: Improve SFP 100Mbps auto-negotiation

After changing speed to 100Mbps as a result of auto-negotiation (AN),
some 10/100/1000Mbps SFPs indicate a successful link (no faults or loss
of signal), but cannot successfully transmit or receive data.  These
SFPs required an extra auto-negotiation (AN) after the speed change in
order to operate properly.  Add a quirk for these SFPs so that if the
outcome of the AN actually results in changing to a new speed, re-initiate
AN at that new speed.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/amd/xgbe/xgbe-mdio.c

@@ -331,13 +331,15 @@ static void xgbe_switch_mode(struct xgbe_prv_data *pdata)
 	xgbe_change_mode(pdata, pdata->phy_if.phy_impl.switch_mode(pdata));
 }
 
-static void xgbe_set_mode(struct xgbe_prv_data *pdata,
+static bool xgbe_set_mode(struct xgbe_prv_data *pdata,
 			  enum xgbe_mode mode)
 {
 	if (mode == xgbe_cur_mode(pdata))
-		return;
+		return false;
 
 	xgbe_change_mode(pdata, mode);
+
+	return true;
 }
 
 static bool xgbe_use_mode(struct xgbe_prv_data *pdata,
@@ -1178,21 +1180,23 @@ static int xgbe_phy_config_fixed(struct xgbe_prv_data *pdata)
 	return 0;
 }
 
-static int __xgbe_phy_config_aneg(struct xgbe_prv_data *pdata)
+static int __xgbe_phy_config_aneg(struct xgbe_prv_data *pdata, bool set_mode)
 {
 	int ret;
 
+	mutex_lock(&pdata->an_mutex);
+
 	set_bit(XGBE_LINK_INIT, &pdata->dev_state);
 	pdata->link_check = jiffies;
 
 	ret = pdata->phy_if.phy_impl.an_config(pdata);
 	if (ret)
-		return ret;
+		goto out;
 
 	if (pdata->phy.autoneg != AUTONEG_ENABLE) {
 		ret = xgbe_phy_config_fixed(pdata);
 		if (ret || !pdata->kr_redrv)
-			return ret;
+			goto out;
 
 		netif_dbg(pdata, link, pdata->netdev, "AN redriver support\n");
 	} else {
@@ -1202,6 +1206,7 @@ static int __xgbe_phy_config_aneg(struct xgbe_prv_data *pdata)
 	/* Disable auto-negotiation interrupt */
 	disable_irq(pdata->an_irq);
 
+	if (set_mode) {
 		/* Start auto-negotiation in a supported mode */
 		if (xgbe_use_mode(pdata, XGBE_MODE_KR)) {
 			xgbe_set_mode(pdata, XGBE_MODE_KR);
@@ -1219,7 +1224,9 @@ static int __xgbe_phy_config_aneg(struct xgbe_prv_data *pdata)
 			xgbe_set_mode(pdata, XGBE_MODE_SGMII_100);
 		} else {
 			enable_irq(pdata->an_irq);
-		return -EINVAL;
+			ret = -EINVAL;
+			goto out;
+		}
 	}
 
 	/* Disable and stop any in progress auto-negotiation */
@@ -1239,16 +1246,7 @@ static int __xgbe_phy_config_aneg(struct xgbe_prv_data *pdata)
 	xgbe_an_init(pdata);
 	xgbe_an_restart(pdata);
 
-	return 0;
-}
-
-static int xgbe_phy_config_aneg(struct xgbe_prv_data *pdata)
-{
-	int ret;
-
-	mutex_lock(&pdata->an_mutex);
-
-	ret = __xgbe_phy_config_aneg(pdata);
+out:
 	if (ret)
 		set_bit(XGBE_LINK_ERR, &pdata->dev_state);
 	else
@@ -1259,6 +1257,16 @@ static int xgbe_phy_config_aneg(struct xgbe_prv_data *pdata)
 	return ret;
 }
 
+static int xgbe_phy_config_aneg(struct xgbe_prv_data *pdata)
+{
+	return __xgbe_phy_config_aneg(pdata, true);
+}
+
+static int xgbe_phy_reconfig_aneg(struct xgbe_prv_data *pdata)
+{
+	return __xgbe_phy_config_aneg(pdata, false);
+}
+
 static bool xgbe_phy_aneg_done(struct xgbe_prv_data *pdata)
 {
 	return (pdata->an_result == XGBE_AN_COMPLETE);
@@ -1315,7 +1323,8 @@ static void xgbe_phy_status_result(struct xgbe_prv_data *pdata)
 
 	pdata->phy.duplex = DUPLEX_FULL;
 
-	xgbe_set_mode(pdata, mode);
+	if (xgbe_set_mode(pdata, mode) && pdata->an_again)
+		xgbe_phy_reconfig_aneg(pdata);
 }
 
 static void xgbe_phy_status(struct xgbe_prv_data *pdata)

drivers/net/ethernet/amd/xgbe/xgbe-phy-v2.c

@@ -902,6 +902,9 @@ static bool xgbe_phy_belfuse_phy_quirks(struct xgbe_prv_data *pdata)
 		   XGBE_BEL_FUSE_VENDOR, XGBE_SFP_BASE_VENDOR_NAME_LEN))
 		return false;
 
+	/* For Bel-Fuse, use the extra AN flag */
+	pdata->an_again = 1;
+
 	if (memcmp(&sfp_eeprom->base[XGBE_SFP_BASE_VENDOR_PN],
 		   XGBE_BEL_FUSE_PARTNO, XGBE_SFP_BASE_VENDOR_PN_LEN))
 		return false;
@@ -978,6 +981,9 @@ static int xgbe_phy_find_phy_device(struct xgbe_prv_data *pdata)
 	if (phy_data->phydev)
 		return 0;
 
+	/* Clear the extra AN flag */
+	pdata->an_again = 0;
+
 	/* Check for the use of an external PHY */
 	if (phy_data->phydev_mode == XGBE_MDIO_MODE_NONE)
 		return 0;

drivers/net/ethernet/amd/xgbe/xgbe.h

@@ -1261,6 +1261,7 @@ struct xgbe_prv_data {
 	enum xgbe_rx kr_state;
 	enum xgbe_rx kx_state;
 	struct work_struct an_work;
+	unsigned int an_again;
 	unsigned int an_supported;
 	unsigned int parallel_detect;
 	unsigned int fec_ability;