Re: [Linuxptp-users] Synchronization fault with stmmac

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

On Tue, 2014-03-25 at 15:29 +0100, Richard Cochran wrote:
> On Tue, Mar 25, 2014 at 02:38:29PM +0100, Mohamed Belaouad wrote:
> 
> > Considering that the drivers sets the max adj to 62,500,000, I
> > should be able to set the ppb ajustment up/down to -+62,500,000 from
> > my understanding.
> 
> Yes, that is correct.
> 
> > However, when printing the value passed to the driver with testptp I get:
> >    Value passed to testptp | Value printed at the entry of the driver function
> >        > +32,768,000       |   -32,768,000
> >        < -32,768,000       |   -32,768,000
> 
> I guess you are on a 32 bit platform. In that case, the size of the
> adjustment is limited by the timex.freq field. See linuxptp/phc.c.
> 
> > Please excuse me if it is a misunderstanding on my part.
> 
> I thought you meant that the kernel should check that the dialed
> frequency offset is within the bounds of [-max_adj, +max_adj].
> That is a different issue.
> 

I think that change to the kernel would be a good thing, since most
drivers assume that the value passed to them is within range.

Regards,
Jake

> Thanks,
> Richard
>