Changes between Version 3 and Version 4 of timesync


Ignore:
Timestamp:
12/06/2018 07:15:06 PM (5 years ago)
Author:
Cale Collins
Comment:

added octeon tx section

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  • timesync

    v3 v4  
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    98             <span><a href="/wiki/linux/timesync?action=diff&amp;version=2" title="Version 2 by tharvey: added example usage">Last modified</a> <a class="timeline" href="/timeline?from=2015-08-27T16%3A41%3A56-07%3A00&amp;precision=second" title="See timeline at 08/27/15 16:41:56">2 years ago</a></span>
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     97= Octeon TX IEEE 1588
    12298
    123 }}}
     99From CN80xx refrence manual:
     100
     101The CN80XX hardware supports very accurate timestamping in the PTP, BGX, GTI,
     102and NIC blocks. This timestamping is suitable for use in IEEE 1588 Precision Time
     103Protocol (PTP) or other purposes.
     104
     105The CN80XX outbound timestamping hardware captures timestamps, but cannot
     106insert the timestamp into any outgoing packets. Using IEEE 1588 vernacular, this
     107means that the CN80XX outbound timestamping hardware is most useful when
     108implementing a two-step clock, not a one-step clock, for PTP event messages sent
     109from CN80XX. After the hardware captures the timestamp for the outgoing 1588
     110event message and delivers it to software, the 1588 software running on the CN80XX
     111may need to send the timestamp to required recipients in a subsequent 1588 general
     112message as a second step.
     113
     114NIC has no specific mode supporting PTP timestamping, but contains a number of
     115features to compensate for the PTP timestamp introduced by BGX when it is
     116timestamping.
     117When BGX is in the receive-timestamp mode, NIC receives the timestamp plus
     118packet from the BGX. NIC packet parsing is able to skip over the received
     119timestamps (NIC_PF_PKIND(0..15)_CFG[HDR_SL]). NIC MAXERR, MINERR, and
     120LENERR checks can compensate for the additional header, since the MAXERR and
     121MINERR byte counts are programmable, and the programmed value can easily be
     122increased by 8. The LENERR check already compensates based on the skip value.
     123NIC makes the timestamp available for software with every packet. The timestamp
     124can be present in the completion-queue entry and/or the receive buffer in L2/DRAM
     125for software, depending on NIC configuration. The software will likely use the
     126timestamp when IEEE 1588 event messages arrive. For other packets, the software
     127may choose to discard or ignore the timestamp that is present with every packet in
     128this mode.
     129
     130[[Image(cavium-octeon-tx-block-diagram.jpg, width=600)]]