• Kshitiz Gupta's avatar
    igb: fix adjusting PTP timestamps for Tx/Rx latency · 0066c8b6
    Kshitiz Gupta authored
    
    
    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: default avatarKshitiz Gupta <kshitiz.gupta@ni.com>
    Fixes: 3f544d2a
    
     (igb: adjust ptp timestamps for tx/rx latency)
    Tested-by: default avatarAaron Brown <aaron.f.brown@intel.com>
    Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
    0066c8b6