Hi Vladimir
Could you please send me the patch? I did not find a place to download it.
I also would like to confirm with you that.
FEC supports pps, but I could not run ptp on it. So i could not get pps as no
ptp stacking is running on it.
Swith supports external time stamps channel, can run ptp on it and sync to a
ptp master or slave by L2 transport.
With your patch, I can get fec syncd to switch, right? just like ptp is running
on it ? switch can correct the phc of fec, right?
And this will make pps out of fec? Do I still need to enable the
pps_enable node?
# echo 1 > /sys/class/ptp/ptp0/pps_enable
[ 3184.501924] fec 30be0000.ethernet: No ptp stack is running
# ./testptp -d /dev/ptp1 -c -----switch
capabilities:
1000000 maximum frequency adjustment (ppb)
0 programmable alarms
1 external time stamp channels
0 programmable periodic signals
0 pulse per second
15 programmable pins
0 cross timestamping
# ./testptp -d /dev/ptp0 -c
-------- fec
capabilities:
250000000 maximum frequency adjustment (ppb)
0 programmable alarms
0 external time stamp channels
0 programmable periodic signals
1 pulse per second
0 programmable pins
0 cross timestamping
Thank you
Yvonne
------------------ 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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