Thank you, Richard.  I will follow up with the hardware manufacturer.  Perhaps 
it's just a hardware configuration issue. 

-----Original Message-----
From: Richard Cochran [mailto:richardcoch...@gmail.com] 
Sent: Monday, August 17, 2020 4:51 PM
To: Irene Kravets <ire...@sapling-inc.com>
Cc: linuxptp-users@lists.sourceforge.net
Subject: Re: [Linuxptp-users] Can ptp4l be used without phc2sys?

On Mon, Aug 17, 2020 at 08:34:29PM +0000, Irene Kravets wrote:
> Output of phc_ctl eth0:
> 
> phc_ctl[28.658]:
> capabilities:
>   250000000 maximum frequency adjustment (ppb)
>   0 programable alarms
>   0 external time stamp channels
>   0 programmable periodic signals

Your PHC has zero periodic output signals available.  This means that this 
hardware cannot produce a high quality PPS output.

>   has pulse per second support

This a "virtual" PPS time stamp delivered to the kernel.  It can be used by 
phc2sys or ntpd in order to discipline the Linux system time.
However, it is not a great source of an output PPS signal.  I guess your PPS 
comes from here, and the 2-3 microsecond delay is to be expected.

Sorry,
Richard



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