Merge branch 'amd-xgbe-rx-adaptation-and-phy-handling-fixes'

Raju Rangoju says:

====================
amd-xgbe: RX adaptation and PHY handling fixes

This series fixes several issues in the amd-xgbe driver related to RX
adaptation and PHY handling in 10GBASE-KR mode, particularly when
auto-negotiation is disabled.

Patch 1 fixes link status handling during RX adaptation by correctly
reading the latched link status bit so transient link drops are
detected without losing the current state.

Patch 2 prevents CRC errors that can occur when performing RX
adaptation with auto-negotiation turned off. The driver now stops
TX/RX before re-triggering RX adaptation and only re-enables traffic
once adaptation completes and the link is confirmed up, ensuring
packets are not corrupted during the adaptation window.

Patch 3 restores the intended ordering of PHY reset relative to
phy_start(), making sure PHY settings are reset before the PHY is
started instead of afterwards.
====================

Link: https://patch.msgid.link/20260306111629.1515676-1-Raju.Rangoju@amd.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: Paolo Abeni

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

@@ -1271,20 +1271,25 @@ static int xgbe_start(struct xgbe_prv_data *pdata)
 	if (ret)
 		goto err_napi;
 
+	/* Reset the phy settings */
+	ret = xgbe_phy_reset(pdata);
+	if (ret)
+		goto err_irqs;
+
+	/* Start the phy */
 	ret = phy_if->phy_start(pdata);
 	if (ret)
 		goto err_irqs;
 
 	hw_if->enable_tx(pdata);
 	hw_if->enable_rx(pdata);
+	/* Synchronize flag with hardware state after enabling TX/RX.
+	 * This prevents stale state after device restart cycles.
+	 */
+	pdata->data_path_stopped = false;
 
 	udp_tunnel_nic_reset_ntf(netdev);
 
-	/* Reset the phy settings */
-	ret = xgbe_phy_reset(pdata);
-	if (ret)
-		goto err_txrx;
-
 	netif_tx_start_all_queues(netdev);
 
 	xgbe_start_timers(pdata);
@@ -1294,10 +1299,6 @@ static int xgbe_start(struct xgbe_prv_data *pdata)
 
 	return 0;
 
-err_txrx:
-	hw_if->disable_rx(pdata);
-	hw_if->disable_tx(pdata);
-
 err_irqs:
 	xgbe_free_irqs(pdata);
 

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

@@ -1942,7 +1942,7 @@ static void xgbe_set_rx_adap_mode(struct xgbe_prv_data *pdata,
 static void xgbe_rx_adaptation(struct xgbe_prv_data *pdata)
 {
 	struct xgbe_phy_data *phy_data = pdata->phy_data;
-	unsigned int reg;
+	int reg;
 
 	/* step 2: force PCS to send RX_ADAPT Req to PHY */
 	XMDIO_WRITE_BITS(pdata, MDIO_MMD_PMAPMD, MDIO_PMA_RX_EQ_CTRL4,
@@ -1964,11 +1964,20 @@ static void xgbe_rx_adaptation(struct xgbe_prv_data *pdata)
 
 	/* Step 4: Check for Block lock */
 
-	/* Link status is latched low, so read once to clear
-	 * and then read again to get current state
-	 */
-	reg = XMDIO_READ(pdata, MDIO_MMD_PCS, MDIO_STAT1);
 	reg = XMDIO_READ(pdata, MDIO_MMD_PCS, MDIO_STAT1);
+	if (reg < 0)
+		goto set_mode;
+
+	/* Link status is latched low so that momentary link drops
+	 * can be detected. If link was already down read again
+	 * to get the latest state.
+	 */
+	if (!pdata->phy.link && !(reg & MDIO_STAT1_LSTATUS)) {
+		reg = XMDIO_READ(pdata, MDIO_MMD_PCS, MDIO_STAT1);
+		if (reg < 0)
+			goto set_mode;
+	}
+
 	if (reg & MDIO_STAT1_LSTATUS) {
 		/* If the block lock is found, update the helpers
 		 * and declare the link up
@@ -2008,6 +2017,48 @@ static void xgbe_phy_rx_adaptation(struct xgbe_prv_data *pdata)
 	xgbe_rx_adaptation(pdata);
 }
 
+/*
+ * xgbe_phy_stop_data_path - Stop TX/RX to prevent packet corruption
+ * @pdata: driver private data
+ *
+ * This function stops the data path (TX and RX) to prevent packet
+ * corruption during critical PHY operations like RX adaptation.
+ * Must be called before initiating RX adaptation when link goes down.
+ */
+static void xgbe_phy_stop_data_path(struct xgbe_prv_data *pdata)
+{
+	if (pdata->data_path_stopped)
+		return;
+
+	/* Stop TX/RX to prevent packet corruption during RX adaptation */
+	pdata->hw_if.disable_tx(pdata);
+	pdata->hw_if.disable_rx(pdata);
+	pdata->data_path_stopped = true;
+
+	netif_dbg(pdata, link, pdata->netdev,
+		  "stopping data path for RX adaptation\n");
+}
+
+/*
+ * xgbe_phy_start_data_path - Re-enable TX/RX after RX adaptation
+ * @pdata: driver private data
+ *
+ * This function re-enables the data path (TX and RX) after RX adaptation
+ * has completed successfully. Only called when link is confirmed up.
+ */
+static void xgbe_phy_start_data_path(struct xgbe_prv_data *pdata)
+{
+	if (!pdata->data_path_stopped)
+		return;
+
+	pdata->hw_if.enable_rx(pdata);
+	pdata->hw_if.enable_tx(pdata);
+	pdata->data_path_stopped = false;
+
+	netif_dbg(pdata, link, pdata->netdev,
+		  "restarting data path after RX adaptation\n");
+}
+
 static void xgbe_phy_rx_reset(struct xgbe_prv_data *pdata)
 {
 	int reg;
@@ -2801,22 +2852,39 @@ static int xgbe_phy_link_status(struct xgbe_prv_data *pdata, int *an_restart)
 	if (pdata->en_rx_adap) {
 		/* if the link is available and adaptation is done,
 		 * declare link up
+		 *
+		 * Note: When link is up and adaptation is done, we can
+		 * safely re-enable the data path if it was stopped
+		 * for adaptation.
 		 */
-		if ((reg & MDIO_STAT1_LSTATUS) && pdata->rx_adapt_done)
+		if ((reg & MDIO_STAT1_LSTATUS) && pdata->rx_adapt_done) {
+			xgbe_phy_start_data_path(pdata);
 			return 1;
+		}
 		/* If either link is not available or adaptation is not done,
 		 * retrigger the adaptation logic. (if the mode is not set,
 		 * then issue mailbox command first)
 		 */
+
+		/* CRITICAL: Stop data path BEFORE triggering RX adaptation
+		 * to prevent CRC errors from packets corrupted during
+		 * the adaptation process. This is especially important
+		 * when AN is OFF in 10G KR mode.
+		 */
+		xgbe_phy_stop_data_path(pdata);
+
 		if (pdata->mode_set) {
 			xgbe_phy_rx_adaptation(pdata);
 		} else {
 			pdata->rx_adapt_done = false;
 			xgbe_phy_set_mode(pdata, phy_data->cur_mode);
 		}
 
-		if (pdata->rx_adapt_done)
+		if (pdata->rx_adapt_done) {
+			/* Adaptation complete, safe to re-enable data path */
+			xgbe_phy_start_data_path(pdata);
 			return 1;
+		}
 	} else if (reg & MDIO_STAT1_LSTATUS)
 		return 1;
 

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

@@ -1243,6 +1243,10 @@ struct xgbe_prv_data {
 	bool en_rx_adap;
 	int rx_adapt_retries;
 	bool rx_adapt_done;
+	/* Flag to track if data path (TX/RX) was stopped for RX adaptation.
+	 * This prevents packet corruption during the adaptation window.
+	 */
+	bool data_path_stopped;
 	bool mode_set;
 	bool sph;
 };