Hi Vladimir
Thank you for your reply, my purpose is to get pps and then send to fpga in our
design.Running with dsa. I can only get switch synced using ptp. I could not
get ptp running on fec. I will try your patch to see if it works, it seems it
should work, thank you.
------------------ Original ------------------
From: "Vladimir Oltean";<olte...@gmail.com>;
Date: Nov 5, 2020
To: "yvonne_cyh"<1992184...@qq.com>;
Cc: "Richard Cochran"<richardcoch...@gmail.com>;
"linuxptp-users@lists.sourceforge.net"<linuxptp-users@lists.sourceforge.net>;
Subject: Re: [Linuxptp-users] is there a workaround for us to get pps
out??
On Wed, Nov 04, 2020 at 03:35:19PM +0800, yvonne_cyh wrote:
> We could like to get pps supported by eth0, since dsa driver of marvel
> switch we are using does not support pps.
So your FEC supports periodic output, and the mv88e6xxx switch supports
external timestamping, but you would like the periodic output signal to
be coming from the switch and not the FEC, right?
Even if they were not intended for that purpose, my patches here
https://sourceforge.net/p/linuxptp/mailman/linuxptp-devel/thread/20200830234525.3311891-1-olteanv%40gmail.com/#msg37097414
should make that possible. Basically you could use ts2phc in a reverse
synchronization setup. The FEC is PPS master and synchronization slave,
and the mv88e6xxx is PPS slave and synchronization master. The ts2phc
program runs a servo loop that corrects the FEC's clock until it is in
sync with the mv88e6xxx clock (which itself is connected to the PTP
network, unlike the FEC clock, which is also something that Richard
pointed out). Then, you would need to fan-out the periodic output pin of
the FEC towards another pad on your board, where you could tap it and
use it for whatever other purposes you might need it for. Because it's
synchronized by ts2phc, it's as if that periodic output was generated by
the mv88e6xxx.
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