netdev - [PATCH net-next 2/2] ixgbe: Filter out spurious link up indication

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Message-Id: <20230113214248.970670-3-anthony.l.nguyen@intel.com>
Date:   Fri, 13 Jan 2023 13:42:48 -0800
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com
Cc:     Sebastian Czapla <sebastianx.czapla@...el.com>,
        netdev@...r.kernel.org, anthony.l.nguyen@...el.com,
        Sunitha Mekala <sunithax.d.mekala@...el.com>
Subject: [PATCH net-next 2/2] ixgbe: Filter out spurious link up indication

From: Sebastian Czapla <sebastianx.czapla@...el.com>

Add delayed link state recheck to filter false link up indication
caused by transceiver with no fiber cable attached.

Signed-off-by: Sebastian Czapla <sebastianx.czapla@...el.com>
Tested-by: Sunitha Mekala <sunithax.d.mekala@...el.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 .../net/ethernet/intel/ixgbe/ixgbe_common.c   | 21 ++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_common.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_common.c
index 38c4609bd429..878dd8dff528 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_common.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_common.c
@@ -3292,13 +3292,14 @@ static bool ixgbe_need_crosstalk_fix(struct ixgbe_hw *hw)
 s32 ixgbe_check_mac_link_generic(struct ixgbe_hw *hw, ixgbe_link_speed *speed,
 				 bool *link_up, bool link_up_wait_to_complete)
 {
+	bool crosstalk_fix_active = ixgbe_need_crosstalk_fix(hw);
 	u32 links_reg, links_orig;
 	u32 i;
 
 	/* If Crosstalk fix enabled do the sanity check of making sure
 	 * the SFP+ cage is full.
 	 */
-	if (ixgbe_need_crosstalk_fix(hw)) {
+	if (crosstalk_fix_active) {
 		u32 sfp_cage_full;
 
 		switch (hw->mac.type) {
@@ -3346,10 +3347,24 @@ s32 ixgbe_check_mac_link_generic(struct ixgbe_hw *hw, ixgbe_link_speed *speed,
 			links_reg = IXGBE_READ_REG(hw, IXGBE_LINKS);
 		}
 	} else {
-		if (links_reg & IXGBE_LINKS_UP)
+		if (links_reg & IXGBE_LINKS_UP) {
+			if (crosstalk_fix_active) {
+				/* Check the link state again after a delay
+				 * to filter out spurious link up
+				 * notifications.
+				 */
+				mdelay(5);
+				links_reg = IXGBE_READ_REG(hw, IXGBE_LINKS);
+				if (!(links_reg & IXGBE_LINKS_UP)) {
+					*link_up = false;
+					*speed = IXGBE_LINK_SPEED_UNKNOWN;
+					return 0;
+				}
+			}
 			*link_up = true;
-		else
+		} else {
 			*link_up = false;
+		}
 	}
 
 	switch (links_reg & IXGBE_LINKS_SPEED_82599) {
-- 
2.38.1