From mboxrd@z Thu Jan  1 00:00:00 1970
From: Denny Page <dennypage@me.com>
Subject: Re: Extending socket timestamping API for NTP
Date: Thu, 09 Feb 2017 16:33:19 -0800
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Cc: Miroslav Lichvar <mlichvar@redhat.com>,
        Richard Cochran <richardcochran@gmail.com>,
        netdev <netdev@vger.kernel.org>, Jiri Benc <jbenc@redhat.com>,
        "Keller, Jacob E" <jacob.e.keller@intel.com>,
        Willem de Bruijn <willemb@google.com>
To: sdncurious <sdncurious@gmail.com>
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> On Feb 09, 2017, at 11:42, sdncurious <sdncurious@gmail.com> wrote:
>=20
> I am still at a loss as to why transpose is required in case of HW
> time stamping. If STF is used for both Tx and Rx time stamping the
> timing is absolutely correct.

Perhaps this will help. The specific transposition is:

  transposed_timestamp_ns =3D timestamp_ns + (frame_len_bits * =
1000000000) / (interface_speed * 1000000)

The transposition is applied to received timestamps only.

Denny