Re: [Linuxptp-users] Synchronization fault with stmmac

[Keller, J. E <jac...@in...>]

On Wed, 2014-03-19 at 10:46 +0100, Richard Cochran wrote:
> On Wed, Mar 19, 2014 at 09:54:00AM +0100, Mohamed Belaouad wrote:
> 
> > From the first test I did (running ptp4l to get the PC time then
> > stopping it), the board ptp time seems to run slower than the PC
> > time. While 5 minutes elapsed on the PC, 2/3min only do on the
> > board.
> 
> You can easily test the clock speed like this.
> 
>     testptp -g
>     sleep 60
>     testptp -g
> 
> Then, see if 60 seconds elapsed.
> 
> Thanks,
> Richard

Also test with various adjustment frequencies applied, I don't know
exact commands here, but you can do something like:

adjust frequency by 50% (500 million ppb)
set clock to system time or 0
get time
sleep some amount of time
get time

then check to see if the expected time adjusted by the frequency change
has actually passed.

In this way, you can see whether frequency adjustment is working right,
since if you modify the clock frequency by say.. 1.5x, then you should
see roughly an equivalent decrease in the time different on clock, of
"time difference / 1.5".

Please do these experiments using testptp first and see if things make
sense. This will help limit the scope of the tests so you can see what
parts might be failing.

I would suggest attempting to set the ppb to the maximum value your
driver allows as well, to check to see if the adjustment is overflowing
somehow.

Regards,
Jake