Re: [Linuxptp-users] Status file of achieved time synchronization

[Koehrer M. (ETAS/ESW5) <mat...@et...>]

Hi Richard,

thanks for the support!
> From: Richard Cochran 
> Sent: Friday, February 14, 2014 9:35 PM
> > Or how do I have to call "phc2sys" in the situation when I do not know if the
> PC will be master or not?
> 
> You can simply do the same as in the slave case.
> 
>     phc2sys -s /dev/ptp -w
> 
> The grand master node will adjust its system time to the free running
> PTP Hardware Clock. You will want to set the correct time in the PHC
> before doing this!
OK that makes sense! Which tool can I use to set the correct time in the PHC before starting phc2sys?
Can I use phc2sys or is there another tool required for this?
I assume, in this case I have to consider the 35s offset...


One thing that is still not clear to me is how to get the accuracy of the local clock in relation to the PTP master clock.
Using pmc I can get the drift/offset of my local PHC device in relation to the PTP master clock.
However I did not understand yet how I can retrieve the current drift/offset of my system clock (CLOCK_REALTIME) in relation to the PTP master clock.
As my application runs using the system clock I have to ensure that the offset/drift is small enough to be able to start the application.
phc2sys is responsible to adapt the system clock, thus I'd expected phc2sys to deliver this information somehow. However I do not find anything like that in the code or man page.

Thanks for some hints on that.

Regards

Mathias