Uploaded image for project: 'OpenShift Bugs'
  1. OpenShift Bugs
  2. OCPBUGS-19838

PTP HW Clock Class after disabling NMEA sentences

XMLWordPrintable

    • No
    • True
    • Hide

      Need to find a solution to identify different time source  when nmea string is lost

      Show
      Need to find a solution to identify different time source  when nmea string is lost
    • Hide
      The current PTP grandmaster clock (T-GM) implementation has a single National Marine Electronics Association (NMEA) sentence generator sourced from the GNSS without a backup NMEA sentence generator.
      If NMEA sentences are lost before reaching the e810 NIC, the T-GM cannot synchronize the devices in the network synchronization chain and the PTP Operator reports an error.
      A proposed fix is to report a `FREERUN` event when the NMEA string is lost.
      Until this limitation is addressed, T-GM does not support PTP clock holdover state.
      Show
      The current PTP grandmaster clock (T-GM) implementation has a single National Marine Electronics Association (NMEA) sentence generator sourced from the GNSS without a backup NMEA sentence generator. If NMEA sentences are lost before reaching the e810 NIC, the T-GM cannot synchronize the devices in the network synchronization chain and the PTP Operator reports an error. A proposed fix is to report a `FREERUN` event when the NMEA string is lost. Until this limitation is addressed, T-GM does not support PTP clock holdover state.
    • 6/20: ts2phc supports holdover. need to have a follow up discussion

      Description of problem:

      T-GM clock class announced with ptp4l  

      Version-Release number of selected component (if applicable):

      PTP Operator Version: 4.14.0-202309202002

      How reproducible:

      Always

      Steps to Reproduce:

      1. Deploy linuxptp-daemon
      2. Check PTP HW clock class state with PMC is LOCKED (6)
      # pmc -u -f /var/run/ptp4l.0.config  'GET GRANDMASTER_SETTINGS_NP'
      sending: GET GRANDMASTER_SETTINGS_NP
      	507c6f.fffe.1fb3f8-0 seq 0 RESPONSE MANAGEMENT GRANDMASTER_SETTINGS_NP 
      		clockClass              6
      		clockAccuracy           0x21
      		offsetScaledLogVariance 0x4e5d
      		currentUtcOffset        37
      		leap61                  0
      		leap59                  0
      		currentUtcOffsetValid   0
      		ptpTimescale            1
      		timeTraceable           0
      		frequencyTraceable      0
      		timeSource              0xa0 
      3. disable NMEA sentences from arriving to E810 CVL 
       # ubxtool -d NMEA
      
      4. Check Clock Class:
      
      # pmc -u -f /var/run/ptp4l.0.config  'GET GRANDMASTER_SETTINGS_NP'
      sending: GET GRANDMASTER_SETTINGS_NP
      	507c6f.fffe.1fb3f8-0 seq 0 RESPONSE MANAGEMENT GRANDMASTER_SETTINGS_NP 
      		clockClass              6
      		clockAccuracy           0x21
      		offsetScaledLogVariance 0x4e5d
      		currentUtcOffset        37
      		leap61                  0
      		leap59                  0
      		currentUtcOffsetValid   0
      		ptpTimescale            1
      		timeTraceable           0
      		frequencyTraceable      0
      		timeSource              0xa0

      Actual results:

      clockClass is 6 (LOCKED)

      Expected results:

      Without a way to inject NMEA sentences T-GM cant synchronize. We need a way to generate NMEA sentences so that ts2phc can synchronise if we lose NMEA sentences from GNSS. This is a problem that needs some work. Not perfect because ts2phc needs the seconds from somewhere (need time source) like generating synthetic NMEA sentences.

      Additional info:

      Note that when announcing a clockClass 6 or clockClass 7 ALWAYS the "timeTraceable" and freqencyTraceable" should be set to True.

            aputtur@redhat.com Aneesh Puttur
            jnunez@redhat.com Jose Nuñez
            Hen Shay Hassid Hen Shay Hassid
            Pasi Vaananen
            Votes:
            0 Vote for this issue
            Watchers:
            6 Start watching this issue

              Created:
              Updated: