e1000e: move force SMBUS near the end of enable_ulp function

[ Upstream commit bfd546a ]

The commit 861e808 ("e1000e: move force SMBUS from enable ulp
function to avoid PHY loss issue") introduces a regression on
PCH_MTP_I219_LM18 (PCIID: 0x8086550A). Without the referred commit, the
ethernet works well after suspend and resume, but after applying the
commit, the ethernet couldn't work anymore after the resume and the
dmesg shows that the NIC link changes to 10Mbps (1000Mbps originally):

    [   43.305084] e1000e 0000:00:1f.6 enp0s31f6: NIC Link is Up 10 Mbps Full Duplex, Flow Control: Rx/Tx

Without the commit, the force SMBUS code will not be executed if
"return 0" or "goto out" is executed in the enable_ulp(), and in my
case, the "goto out" is executed since FWSM_FW_VALID is set. But after
applying the commit, the force SMBUS code will be ran unconditionally.

Here move the force SMBUS code back to enable_ulp() and put it
immediately ahead of hw->phy.ops.release(hw), this could allow the
longest settling time as possible for interface in this function and
doesn't change the original code logic.

The issue was found on a Lenovo laptop with the ethernet hw as below:
00:1f.6 Ethernet controller [0200]: Intel Corporation Device [8086:550a]
(rev 20).

And this patch is verified (cable plug and unplug, system suspend
and resume) on Lenovo laptops with ethernet hw: [8086:550a],
[8086:550b], [8086:15bb], [8086:15be], [8086:1a1f], [8086:1a1c] and
[8086:0dc7].

Fixes: 861e808 ("e1000e: move force SMBUS from enable ulp function to avoid PHY loss issue")
Signed-off-by: Hui Wang <[email protected]>
Acked-by: Vitaly Lifshits <[email protected]>
Tested-by: Naama Meir <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Reviewed-by: Paul Menzel <[email protected]>
Signed-off-by: Tony Nguyen <[email protected]>
Tested-by: Zhang Rui <[email protected]>
Signed-off-by: Jacob Keller <[email protected]>
Link: https://lore.kernel.org/r/20240528-net-2024-05-28-intel-net-fixes-v1-1-dc8593d2bbc6@intel.com
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

drivers/net/ethernet/intel/e1000e/ich8lan.c

@@ -1225,6 +1225,28 @@ s32 e1000_enable_ulp_lpt_lp(struct e1000_hw *hw, bool to_sx)
 	}
 
 release:
+	/* Switching PHY interface always returns MDI error
+	 * so disable retry mechanism to avoid wasting time
+	 */
+	e1000e_disable_phy_retry(hw);
+
+	/* Force SMBus mode in PHY */
+	ret_val = e1000_read_phy_reg_hv_locked(hw, CV_SMB_CTRL, &phy_reg);
+	if (ret_val) {
+		e1000e_enable_phy_retry(hw);
+		hw->phy.ops.release(hw);
+		goto out;
+	}
+	phy_reg |= CV_SMB_CTRL_FORCE_SMBUS;
+	e1000_write_phy_reg_hv_locked(hw, CV_SMB_CTRL, phy_reg);
+
+	e1000e_enable_phy_retry(hw);
+
+	/* Force SMBus mode in MAC */
+	mac_reg = er32(CTRL_EXT);
+	mac_reg |= E1000_CTRL_EXT_FORCE_SMBUS;
+	ew32(CTRL_EXT, mac_reg);
+
 	hw->phy.ops.release(hw);
 out:
 	if (ret_val)

drivers/net/ethernet/intel/e1000e/netdev.c

@@ -6623,7 +6623,6 @@ static int __e1000_shutdown(struct pci_dev *pdev, bool runtime)
 	struct e1000_hw *hw = &adapter->hw;
 	u32 ctrl, ctrl_ext, rctl, status, wufc;
 	int retval = 0;
-	u16 smb_ctrl;
 
 	/* Runtime suspend should only enable wakeup for link changes */
 	if (runtime)
@@ -6701,23 +6700,6 @@ static int __e1000_shutdown(struct pci_dev *pdev, bool runtime)
 				goto skip_phy_configurations;
 			}
 		}
-
-		/* Force SMBUS to allow WOL */
-		/* Switching PHY interface always returns MDI error
-		 * so disable retry mechanism to avoid wasting time
-		 */
-		e1000e_disable_phy_retry(hw);
-
-		e1e_rphy(hw, CV_SMB_CTRL, &smb_ctrl);
-		smb_ctrl |= CV_SMB_CTRL_FORCE_SMBUS;
-		e1e_wphy(hw, CV_SMB_CTRL, smb_ctrl);
-
-		e1000e_enable_phy_retry(hw);
-
-		/* Force SMBus mode in MAC */
-		ctrl_ext = er32(CTRL_EXT);
-		ctrl_ext |= E1000_CTRL_EXT_FORCE_SMBUS;
-		ew32(CTRL_EXT, ctrl_ext);
 	}
 
 	/* Ensure that the appropriate bits are set in LPI_CTRL