Commit 0066c8b6 authored by Kshitiz Gupta's avatar Kshitiz Gupta Committed by Jeff Kirsher
Browse files

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

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

- 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: default avatarKshitiz Gupta <>
Fixes: 3f544d2a

 (igb: adjust ptp timestamps for tx/rx latency)
Tested-by: default avatarAaron Brown <>
Signed-off-by: default avatarJeff Kirsher <>
parent a1560dd7
......@@ -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);
......@@ -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),
/* 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;
case SPEED_100:
adjust = IGB_I210_RX_LATENCY_100;
case SPEED_1000:
adjust = IGB_I210_RX_LATENCY_1000;
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.
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