igb: fix adjusting PTP timestamps for Tx/Rx latency

Fix PHY delay compensation math in igb_ptp_tx_hwtstamp() and
igb_ptp_rx_rgtstamp. Add PHY delay compensation in
igb_ptp_rx_pktstamp().

In the IGB driver, there are two functions that retrieve timestamps
received by the PHY - igb_ptp_rx_rgtstamp() and igb_ptp_rx_pktstamp().
The previous commit only changed igb_ptp_rx_rgtstamp(), and the change
was incorrect.

There are two instances in which PHY delay compensations should be
made:

- Before the packet transmission over the PHY, the latency between
  when the packet is timestamped and transmission of the packets,
  should be an add operation, but it is currently a subtract.

- After the packets are received from the PHY, the latency between
  the receiving and timestamping of the packets should be a subtract
  operation, but it is currently an add.

Signed-off-by: Kshitiz Gupta <kshitiz.gupta@ni.com>
Fixes: 3f544d2 (igb: adjust ptp timestamps for tx/rx latency)
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 23 insertions, 3 deletions

diff --git a/drivers/net/ethernet/intel/igb/igb_ptp.c b/drivers/net/ethernet/intel/igb/igb_ptp.c
index e61b647f5f2a..336c103ae374 100644
--- a/drivers/net/ethernet/intel/igb/igb_ptp.c
+++ b/drivers/net/ethernet/intel/igb/igb_ptp.c
@@ -744,7 +744,8 @@ static void igb_ptp_tx_hwtstamp(struct igb_adapter *adapter)
                 }
         }
 
-        shhwtstamps.hwtstamp = ktime_sub_ns(shhwtstamps.hwtstamp, adjust);
+        shhwtstamps.hwtstamp =
+                ktime_add_ns(shhwtstamps.hwtstamp, adjust);
 
         skb_tstamp_tx(adapter->ptp_tx_skb, &shhwtstamps);
         dev_kfree_skb_any(adapter->ptp_tx_skb);
@@ -767,13 +768,32 @@ void igb_ptp_rx_pktstamp(struct igb_q_vector *q_vector,
                          struct sk_buff *skb)
 {
         __le64 *regval = (__le64 *)va;
+        struct igb_adapter *adapter = q_vector->adapter;
+        int adjust = 0;
 
         /* The timestamp is recorded in little endian format.
          * DWORD: 0        1        2        3
          * Field: Reserved Reserved SYSTIML  SYSTIMH
          */
-        igb_ptp_systim_to_hwtstamp(q_vector->adapter, skb_hwtstamps(skb),
+        igb_ptp_systim_to_hwtstamp(adapter, skb_hwtstamps(skb),
                                    le64_to_cpu(regval[1]));
+
+        /* adjust timestamp for the RX latency based on link speed */
+        if (adapter->hw.mac.type == e1000_i210) {
+                switch (adapter->link_speed) {
+                case SPEED_10:
+                        adjust = IGB_I210_RX_LATENCY_10;
+                        break;
+                case SPEED_100:
+                        adjust = IGB_I210_RX_LATENCY_100;
+                        break;
+                case SPEED_1000:
+                        adjust = IGB_I210_RX_LATENCY_1000;
+                        break;
+                }
+        }
+        skb_hwtstamps(skb)->hwtstamp =
+                ktime_sub_ns(skb_hwtstamps(skb)->hwtstamp, adjust);
 }
 
 /**
@@ -825,7 +845,7 @@ void igb_ptp_rx_rgtstamp(struct igb_q_vector *q_vector,
                 }
         }
         skb_hwtstamps(skb)->hwtstamp =
-                ktime_add_ns(skb_hwtstamps(skb)->hwtstamp, adjust);
+                ktime_sub_ns(skb_hwtstamps(skb)->hwtstamp, adjust);
 
         /* Update the last_rx_timestamp timer in order to enable watchdog check
          * for error case of latched timestamp on a dropped packet.