Messages in this thread |  | | Date | Sun, 29 Aug 2010 15:32:20 +0200 | From | Christian Riesch <> | Subject | Re: [PATCH 1/5] ptp: Added a brand new class driver for ptp clocks. |
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Alan Cox wrote: >> The master node in a PTP network probably takes its time from a >> precise external time source, like GPS. The GPS provides a 1 PPS >> directly to the PTP clock hardware, which latches the PTP hardware >> clock time on the PPS edge. This provides one sample as input to a >> clock servo (in the PTPd) that, in turn, regulates the PTP clock >> hardware. > > A PTP clock is TAI, Unix time is UTC.
Not necessarily. AFAIK, the time distributed by IEEE1588v2 can either be based on the "PTP epoch" (timePropertiesDS.ptpTimescale=TRUE) and thus represent TAI or be based on an implementation specific arbitrary epoch (timePropertiesDS.ptpTimescale=FALSE) and represent time on some arbitrary time scale.
Christian
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