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  1. OpenShift Bugs
  2. OCPBUGS-19838

PTP HW Clock Class after disabling NMEA sentences

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

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      Need to find a solution to identify different time source  when nmea string is lost
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      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.
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      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.
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      9/19: will be delivered in 4.18, also will be backported before 4.18 release
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      9/19: will be delivered in 4.18, also will be backported before 4.18 release

      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
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                Created:
                Updated: