linux-kernel - [PATCH v1 net] net: lan743x: Restore SGMII CTRL register on resume

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Message-ID: <20250516035719.117960-1-thangaraj.s@microchip.com>
Date: Fri, 16 May 2025 09:27:19 +0530
From: Thangaraj Samynathan <thangaraj.s@...rochip.com>
To: <bryan.whitehead@...rochip.com>, <UNGLinuxDriver@...rochip.com>,
	<andrew+netdev@...n.ch>, <davem@...emloft.net>, <edumazet@...gle.com>,
	<kuba@...nel.org>, <pabeni@...hat.com>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH v1 net] net: lan743x: Restore SGMII CTRL register on resume

SGMII_CTRL register, which specifies the active interface, was not 
properly restored when resuming from suspend. This led to incorrect
interface selection after resume particularly in scenarios involving
the FPGA.

To fix this:
- Move the SGMII_CTRL setup out of the probe function.
- Initialize the register in the hardware initialization helper function,
which is called during both device initialization and resume.

This ensures the interface configuration is consistently restored after
suspend/resume cycles.

Fixes: a46d9d37c4f4f ("net: lan743x: Add support for SGMII interface")
Signed-off-by: Thangaraj Samynathan <thangaraj.s@...rochip.com>
---
 drivers/net/ethernet/microchip/lan743x_main.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index 880681085df2..7e71579632f3 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -3495,6 +3495,7 @@ static int lan743x_hardware_init(struct lan743x_adapter *adapter,
 				 struct pci_dev *pdev)
 {
 	struct lan743x_tx *tx;
+	u32 sgmii_ctl;
 	int index;
 	int ret;
 
@@ -3507,6 +3508,15 @@ static int lan743x_hardware_init(struct lan743x_adapter *adapter,
 		spin_lock_init(&adapter->eth_syslock_spinlock);
 		mutex_init(&adapter->sgmii_rw_lock);
 		pci11x1x_set_rfe_rd_fifo_threshold(adapter);
+		sgmii_ctl = lan743x_csr_read(adapter, SGMII_CTL);
+		if (adapter->is_sgmii_en) {
+			sgmii_ctl |= SGMII_CTL_SGMII_ENABLE_;
+			sgmii_ctl &= ~SGMII_CTL_SGMII_POWER_DN_;
+		} else {
+			sgmii_ctl &= ~SGMII_CTL_SGMII_ENABLE_;
+			sgmii_ctl |= SGMII_CTL_SGMII_POWER_DN_;
+		}
+		lan743x_csr_write(adapter, SGMII_CTL, sgmii_ctl);
 	} else {
 		adapter->max_tx_channels = LAN743X_MAX_TX_CHANNELS;
 		adapter->used_tx_channels = LAN743X_USED_TX_CHANNELS;
@@ -3558,7 +3568,6 @@ static int lan743x_hardware_init(struct lan743x_adapter *adapter,
 
 static int lan743x_mdiobus_init(struct lan743x_adapter *adapter)
 {
-	u32 sgmii_ctl;
 	int ret;
 
 	adapter->mdiobus = devm_mdiobus_alloc(&adapter->pdev->dev);
@@ -3570,10 +3579,6 @@ static int lan743x_mdiobus_init(struct lan743x_adapter *adapter)
 	adapter->mdiobus->priv = (void *)adapter;
 	if (adapter->is_pci11x1x) {
 		if (adapter->is_sgmii_en) {
-			sgmii_ctl = lan743x_csr_read(adapter, SGMII_CTL);
-			sgmii_ctl |= SGMII_CTL_SGMII_ENABLE_;
-			sgmii_ctl &= ~SGMII_CTL_SGMII_POWER_DN_;
-			lan743x_csr_write(adapter, SGMII_CTL, sgmii_ctl);
 			netif_dbg(adapter, drv, adapter->netdev,
 				  "SGMII operation\n");
 			adapter->mdiobus->read = lan743x_mdiobus_read_c22;
@@ -3584,10 +3589,6 @@ static int lan743x_mdiobus_init(struct lan743x_adapter *adapter)
 			netif_dbg(adapter, drv, adapter->netdev,
 				  "lan743x-mdiobus-c45\n");
 		} else {
-			sgmii_ctl = lan743x_csr_read(adapter, SGMII_CTL);
-			sgmii_ctl &= ~SGMII_CTL_SGMII_ENABLE_;
-			sgmii_ctl |= SGMII_CTL_SGMII_POWER_DN_;
-			lan743x_csr_write(adapter, SGMII_CTL, sgmii_ctl);
 			netif_dbg(adapter, drv, adapter->netdev,
 				  "RGMII operation\n");
 			// Only C22 support when RGMII I/F
-- 
2.25.1