releases/4.19.311/igb-fix-missing-time-sync-events.patch

From 913867b61bb7d30a5325fe0618f495bb3ef294d3 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Tue, 20 Feb 2024 15:57:11 -0800
Subject: igb: Fix missing time sync events

From: Vinicius Costa Gomes <vinicius.gomes@intel.com>

[ Upstream commit ee14cc9ea19ba9678177e2224a9c58cce5937c73 ]

Fix "double" clearing of interrupts, which can cause external events
or timestamps to be missed.

The E1000_TSIRC Time Sync Interrupt Cause register can be cleared in two
ways, by either reading it or by writing '1' into the specific cause
bit. This is documented in section 8.16.1.

The following flow was used:
    1. read E1000_TSIRC into 'tsicr';
    2. handle the interrupts present into 'tsirc' and mark them in 'ack';
    3. write 'ack' into E1000_TSICR;

As both (1) and (3) will clear the interrupt cause, if the same
interrupt happens again between (1) and (3) it will be ignored,
causing events to be missed.

Remove the extra clear in (3).

Fixes: 00c65578b47b ("igb: enable internal PPS for the i210")
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/igb/igb_main.c | 23 +++++------------------
 1 file changed, 5 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index c0e2323e50c6e..5d8d5915bc276 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -6555,44 +6555,31 @@ static void igb_extts(struct igb_adapter *adapter, int tsintr_tt)
 static void igb_tsync_interrupt(struct igb_adapter *adapter)
 {
 	struct e1000_hw *hw = &adapter->hw;
-	u32 ack = 0, tsicr = rd32(E1000_TSICR);
+	u32 tsicr = rd32(E1000_TSICR);
 	struct ptp_clock_event event;
 
 	if (tsicr & TSINTR_SYS_WRAP) {
 		event.type = PTP_CLOCK_PPS;
 		if (adapter->ptp_caps.pps)
 			ptp_clock_event(adapter->ptp_clock, &event);
-		ack |= TSINTR_SYS_WRAP;
 	}
 
 	if (tsicr & E1000_TSICR_TXTS) {
 		/* retrieve hardware timestamp */
 		schedule_work(&adapter->ptp_tx_work);
-		ack |= E1000_TSICR_TXTS;
 	}
 
-	if (tsicr & TSINTR_TT0) {
+	if (tsicr & TSINTR_TT0)
 		igb_perout(adapter, 0);
-		ack |= TSINTR_TT0;
-	}
 
-	if (tsicr & TSINTR_TT1) {
+	if (tsicr & TSINTR_TT1)
 		igb_perout(adapter, 1);
-		ack |= TSINTR_TT1;
-	}
 
-	if (tsicr & TSINTR_AUTT0) {
+	if (tsicr & TSINTR_AUTT0)
 		igb_extts(adapter, 0);
-		ack |= TSINTR_AUTT0;
-	}
 
-	if (tsicr & TSINTR_AUTT1) {
+	if (tsicr & TSINTR_AUTT1)
 		igb_extts(adapter, 1);
-		ack |= TSINTR_AUTT1;
-	}
-
-	/* acknowledge the interrupts */
-	wr32(E1000_TSICR, ack);
 }
 
 static irqreturn_t igb_msix_other(int irq, void *data)
-- 
2.43.0