Changes between Version 4 and Version 5 of timesync


Ignore:
Timestamp:
12/06/2018 07:16:01 PM (11 months ago)
Author:
Cale Collins
Comment:

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  • timesync

    v4 v5  
    9595</div>
    9696
    97 = Octeon TX IEEE 1588
    9897
    99 From CN80xx refrence manual:
    100 
    101 The CN80XX hardware supports very accurate timestamping in the PTP, BGX, GTI,
    102 and NIC blocks. This timestamping is suitable for use in IEEE 1588 Precision Time
    103 Protocol (PTP) or other purposes.
    104 
    105 The CN80XX outbound timestamping hardware captures timestamps, but cannot
    106 insert the timestamp into any outgoing packets. Using IEEE 1588 vernacular, this
    107 means that the CN80XX outbound timestamping hardware is most useful when
    108 implementing a two-step clock, not a one-step clock, for PTP event messages sent
    109 from CN80XX. After the hardware captures the timestamp for the outgoing 1588
    110 event message and delivers it to software, the 1588 software running on the CN80XX
    111 may need to send the timestamp to required recipients in a subsequent 1588 general
    112 message as a second step.
    113 
    114 NIC has no specific mode supporting PTP timestamping, but contains a number of
    115 features to compensate for the PTP timestamp introduced by BGX when it is
    116 timestamping.
    117 When BGX is in the receive-timestamp mode, NIC receives the timestamp plus
    118 packet from the BGX. NIC packet parsing is able to skip over the received
    119 timestamps (NIC_PF_PKIND(0..15)_CFG[HDR_SL]). NIC MAXERR, MINERR, and
    120 LENERR checks can compensate for the additional header, since the MAXERR and
    121 MINERR byte counts are programmable, and the programmed value can easily be
    122 increased by 8. The LENERR check already compensates based on the skip value.
    123 NIC makes the timestamp available for software with every packet. The timestamp
    124 can be present in the completion-queue entry and/or the receive buffer in L2/DRAM
    125 for software, depending on NIC configuration. The software will likely use the
    126 timestamp when IEEE 1588 event messages arrive. For other packets, the software
    127 may choose to discard or ignore the timestamp that is present with every packet in
    128 this mode.
    129 
    130 [[Image(cavium-octeon-tx-block-diagram.jpg, width=600)]]