Re: [Linuxptp-users] Synchronization fault with stmmac

[Mohamed B. <mbe...@ad...>]

Jake,

> Out of curiosity where are you printing the value ppb?

I am printing right at the beginning of stmmac_adjust_freq function (drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c).
So the value should be clean.

> > 
> > The driver implementation is not checking the max frequency adjustment...
> > I still did some tests and strange enough there is a value change to
> > -32,768,000 when passing ppb greater than 32,768,000. Also, the value
> > saturates to -32,768,000 with ppb lesser than -32,768,000.
> > So I am forced to use values between [-32,768,000 | 32,768,000]. I guess
> > your test suggestion will pass once I get through this.
> > 
> > Could you please shed some light on that? Is it something related with the
> > kernel ptp clock driver? I did not find
> > 
> 
> Your driver does have to fill in the maximum value to register to the
> ptp core, and ptp core handles checking, but maybe there is a bug
> regarding that in your kernel... It should be keeping the sign the same
> when it clips the maximum value, however.
> 
> It should be changing it to the max adjust, non negative.
> 
> Look at your driver, where you set the max_adj field of ptp_caps.
> 

It is correctly filled with 62,500,000 and I checked with testptp. So there is still some margin.
I don't know if I am looking at the right location but I did not find any check on max_adj of ppb in drivers/ptp.


Thanks,
Mohamed