igc: Fix missing time sync events

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

The IGC_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 IGC_TSIRC into 'tsicr';
 2. handle the interrupts present in 'tsirc' and mark them in 'ack';
 3. write 'ack' into IGC_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: 2c344ae24501 ("igc: Add support for TX timestamping")
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Tested-by: Kurt Kanzenbach <kurt@linutronix.de> # Intel i225
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 81c21a893ede9c0c432d26e03f3baecc3293b27f..e447ba037056811a0814192dd3011fc55b2600e1 100644 (file)
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -5302,25 +5302,22 @@ igc_features_check(struct sk_buff *skb, struct net_device *dev,
 
 static void igc_tsync_interrupt(struct igc_adapter *adapter)
 {
-       u32 ack, tsauxc, sec, nsec, tsicr;
        struct igc_hw *hw = &adapter->hw;
+       u32 tsauxc, sec, nsec, tsicr;
        struct ptp_clock_event event;
        struct timespec64 ts;
 
        tsicr = rd32(IGC_TSICR);
-       ack = 0;
 
        if (tsicr & IGC_TSICR_SYS_WRAP) {
                event.type = PTP_CLOCK_PPS;
                if (adapter->ptp_caps.pps)
                        ptp_clock_event(adapter->ptp_clock, &event);
-               ack |= IGC_TSICR_SYS_WRAP;
        }
 
        if (tsicr & IGC_TSICR_TXTS) {
                /* retrieve hardware timestamp */
                igc_ptp_tx_tstamp_event(adapter);
-               ack |= IGC_TSICR_TXTS;
        }
 
        if (tsicr & IGC_TSICR_TT0) {
@@ -5334,7 +5331,6 @@ static void igc_tsync_interrupt(struct igc_adapter *adapter)
                wr32(IGC_TSAUXC, tsauxc);
                adapter->perout[0].start = ts;
                spin_unlock(&adapter->tmreg_lock);
-               ack |= IGC_TSICR_TT0;
        }
 
        if (tsicr & IGC_TSICR_TT1) {
@@ -5348,7 +5344,6 @@ static void igc_tsync_interrupt(struct igc_adapter *adapter)
                wr32(IGC_TSAUXC, tsauxc);
                adapter->perout[1].start = ts;
                spin_unlock(&adapter->tmreg_lock);
-               ack |= IGC_TSICR_TT1;
        }
 
        if (tsicr & IGC_TSICR_AUTT0) {
@@ -5358,7 +5353,6 @@ static void igc_tsync_interrupt(struct igc_adapter *adapter)
                event.index = 0;
                event.timestamp = sec * NSEC_PER_SEC + nsec;
                ptp_clock_event(adapter->ptp_clock, &event);
-               ack |= IGC_TSICR_AUTT0;
        }
 
        if (tsicr & IGC_TSICR_AUTT1) {
@@ -5368,11 +5362,7 @@ static void igc_tsync_interrupt(struct igc_adapter *adapter)
                event.index = 1;
                event.timestamp = sec * NSEC_PER_SEC + nsec;
                ptp_clock_event(adapter->ptp_clock, &event);
-               ack |= IGC_TSICR_AUTT1;
        }
-
-       /* acknowledge the interrupts */
-       wr32(IGC_TSICR, ack);
 }
 
 /**