[Linuxptp-devel] phc2sys freezes the system if started before PHY

[Petr K. <br...@ji...>]

Hi,

I'm having an interesting problem with phc2sys. On my embedded iMX6 
board phc2sys is started (together with ptp4l) via systemd during the 
system initialization.
It is called with the following parameters:
phc2sys -s /dev/ptp0 -c CLOCK_REALTIME -w -S 1.0

Until now it worked well, however after the recent update of some 
components the systemd initialization order changed and phc2sys now 
starts before the PHY is initialized, i.e. before the following message 
appears:

fec 2188000.ethernet eth0: Freescale FEC PHY driver [Micrel KSZ8081 or 
KSZ8091] (mii_bus:phy_addr=2188000.ethernet:01, irq=-1)

On this condition the system freezes as soon as the phc2sys starts.
I'm wondering why this happens. Phc2sys uses /dev/ptp0 which is created 
by the kernel very early. Why does it need the PHY to initialize? And 
why does the lack of initialization kills the system?
Not even sure whether this is a problem of phc2sys or of the kernel.

In any case, what would be an appropriate dependency in the systemd 
file? network.target doesn't help and I don't want to necessarily wait 
for the link to come up in network-online.target.

Thanks
Petr