> From: [email protected] [mailto:netdev-
> [email protected]] On Behalf Of Kshitiz Gupta
> Sent: Saturday, July 16, 2016 12:24 AM
> To: Kirsher, Jeffrey T <[email protected]>; Nathan Sullivan
> <[email protected]>; Brown, Aaron F <[email protected]>
> Cc: [email protected]; [email protected]; Kshitiz Gupta
> <[email protected]>
> Subject: [PATCH] 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 <[email protected]>
> Fixes: 3f544d2 (igb: adjust ptp timestamps for tx/rx latency)
> ---
>  drivers/net/ethernet/intel/igb/igb_ptp.c | 26 +++++++++++++++++++++++---
>  1 file changed, 23 insertions(+), 3 deletions(-)

I think I was so engrossed in checking the values for 10 / 100 / 1000 delays 
that I completely missed the reversed add / subtract when looking at 3f544d2.  
Thanks for catching that.
Tested-by: Aaron Brown <[email protected]>

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