Re: [Intel-wired-lan] [PATCH iwl-net v2 1/1] e1000e: fix force smbus during suspend flow

["Brandt, Todd E" <todd.e.brandt@intel.com>]

I just built and tested your patch on the latest 6.10.0-rc3 tip. It seems to have fixed the issue on three of our machines, but the issue still occurs on our Meteor Lake SDV board (otcpl-mtl-s).

[  130.302511] e1000e: EEE TX LPI TIMER: 00000011
[  130.390014] e1000e 0000:80:1f.6: PM: pci_pm_suspend(): e1000e_pm_suspend [e1000e] returns -2
[  130.390033] e1000e 0000:80:1f.6: PM: dpm_run_callback(): pci_pm_suspend returns -2
[  130.390039] e1000e 0000:80:1f.6: PM: failed to suspend async: error -2
[  130.574807] PM: suspend of devices aborted after 293.955 msecs
[  130.574817] PM: start suspend of devices aborted after 376.596 msecs
[  130.574820] PM: Some devices failed to suspend, or early wake event detected

$> lspci -nn -s 80:1f.6
80:1f.6 Ethernet controller [0200]: Intel Corporation Device [8086:550d]

-----Original Message-----
From: Lifshits, Vitaly <vitaly.lifshits@intel.com> 
Sent: Wednesday, June 19, 2024 11:37 PM
To: intel-wired-lan@osuosl.org
Cc: hui.wang@canonical.com; Lifshits, Vitaly <vitaly.lifshits@intel.com>; Brandt, Todd E <todd.e.brandt@intel.com>; Dieter Mummenschanz <dmummenschanz@web.de>
Subject: [PATCH iwl-net v2 1/1] e1000e: fix force smbus during suspend flow

Commit 861e8086029e ("e1000e: move force SMBUS from enable ulp function to avoid PHY loss issue") resolved a PHY access loss during suspend on Meteor Lake consumer platforms, but it affected corporate systems incorrectly.

A better fix, working for both consumer and corporate systems, was proposed in commit bfd546a552e1 ("e1000e: move force SMBUS near the end of enable_ulp function"). However, it introduced a regression on older devices, such as [8086:15B8], [8086:15F9], [8086:15BE].

This patch aims to fix the secondary regression, by limiting the scope of the changes to Meteor Lake platforms only.

Fixes: bfd546a552e1 ("e1000e: move force SMBUS near the end of enable_ulp function")
Reported-by: Todd Brandt <todd.e.brandt@intel.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218940
Reported-by: Dieter Mummenschanz <dmummenschanz@web.de>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218936
Signed-off-by: Vitaly Lifshits <vitaly.lifshits@intel.com>
--
v2: enhance the function description and address community comments
v1: initial version
---
 drivers/net/ethernet/intel/e1000e/ich8lan.c | 73 +++++++++++++++------
 1 file changed, 53 insertions(+), 20 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c b/drivers/net/ethernet/intel/e1000e/ich8lan.c
index 2e98a2a0bead..86d4ae95b45a 100644
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.c
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c
@@ -137,6 +137,7 @@ static void e1000_gate_hw_phy_config_ich8lan(struct e1000_hw *hw, bool gate);  static s32 e1000_disable_ulp_lpt_lp(struct e1000_hw *hw, bool force);  static s32 e1000_setup_copper_link_pch_lpt(struct e1000_hw *hw);  static s32 e1000_oem_bits_config_ich8lan(struct e1000_hw *hw, bool d0_state);
+static s32 e1000e_force_smbus(struct e1000_hw *hw);
 
 static inline u16 __er16flash(struct e1000_hw *hw, unsigned long reg)  { @@ -1108,6 +1109,46 @@ static s32 e1000_platform_pm_pch_lpt(struct e1000_hw *hw, bool link)
 	return 0;
 }
 
+/**
+ *  e1000e_force_smbus - Force interfaces to transition to SMBUS mode.
+ *  @hw: pointer to the HW structure
+ *
+ *  Force the MAC and the PHY to SMBUS mode. Assumes semaphore already
+ *  acquired.
+ *
+ * Return: 0 on success, negative errno on failure.
+ **/
+static s32 e1000e_force_smbus(struct e1000_hw *hw) {
+	u16 smb_ctrl = 0;
+	u32 ctrl_ext;
+	s32 ret_val;
+
+	/* Switching PHY interface always returns MDI error
+	 * so disable retry mechanism to avoid wasting time
+	 */
+	e1000e_disable_phy_retry(hw);
+
+	/* Force SMBus mode in the PHY */
+	ret_val = e1000_read_phy_reg_hv_locked(hw, CV_SMB_CTRL, &smb_ctrl);
+	if (ret_val) {
+		e1000e_enable_phy_retry(hw);
+		return ret_val;
+	}
+
+	smb_ctrl |= CV_SMB_CTRL_FORCE_SMBUS;
+	e1000_write_phy_reg_hv_locked(hw, CV_SMB_CTRL, smb_ctrl);
+
+	e1000e_enable_phy_retry(hw);
+
+	/* Force SMBus mode in the MAC */
+	ctrl_ext = er32(CTRL_EXT);
+	ctrl_ext |= E1000_CTRL_EXT_FORCE_SMBUS;
+	ew32(CTRL_EXT, ctrl_ext);
+
+	return 0;
+}
+
 /**
  *  e1000_enable_ulp_lpt_lp - configure Ultra Low Power mode for LynxPoint-LP
  *  @hw: pointer to the HW structure
@@ -1165,6 +1206,14 @@ s32 e1000_enable_ulp_lpt_lp(struct e1000_hw *hw, bool to_sx)
 	if (ret_val)
 		goto out;
 
+	if (hw->mac.type != e1000_pch_mtp) {
+		ret_val = e1000e_force_smbus(hw);
+		if (ret_val) {
+			e_dbg("Failed to force SMBUS: %d\n", ret_val);
+			goto release;
+		}
+	}
+
 	/* Si workaround for ULP entry flow on i127/rev6 h/w.  Enable
 	 * LPLU and disable Gig speed when entering ULP
 	 */
@@ -1225,27 +1274,11 @@ 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;
+	if (hw->mac.type == e1000_pch_mtp) {
+		ret_val = e1000e_force_smbus(hw);
+		if (ret_val)
+			e_dbg("Failed to force SMBUS over MTL system: %d\n", ret_val);
 	}
-	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:
--
2.34.1