Re: [Linuxptp-users] master offset is increased in some condition

[Takahiro S. <tsh...@gm...>]

Hello Richard,


Yes, you are right, for 32 bit machines.
>
> The problem is that the PHC driver API has the max_adj in ppb, but the
> NTP adjtime API has the frequency adjustment field as ppm with a 16
> bit fractional part.
>
> In the PHC driver API the field is four bytes (type s32), but in the
> NTP adjtime API the field is either four or eight bytes (type long),
> depending on the machine architecture.
>
>
OK. I understand.


> > If I chage the EG20T ptp driver, the result seems OK.
> >
> > static struct ptp_clock_info ptp_pch_caps = {
> > .owner = THIS_MODULE,
> > .name = "PCH timer",
> > // .max_adj = 50000000,
> > .max_adj = 32767999, // Changed the max_adj by TS.
> >
> > (Question)
> > 1. Is my modification correct ?
> > 2. Is it better to correct it in another part?
>
> I think we should change ptp4l to limit the max_adj according to
> the driver's max_adj and sizeof(long).
>
>
I will use the original EG20T ptp driver and modify ptp4l as follows
temporarily.

int phc_max_adj(clockid_t clkid)
{
 int fd = CLOCKID_TO_FD(clkid);
 struct ptp_clock_caps caps;

 if (ioctl(fd, PTP_CLOCK_GETCAPS, &caps)) {
  perror("PTP_CLOCK_GETCAPS");
  return 0;
 }

 if (caps.max_adj > 32767999) // TS Add here.
  caps.max_adj = 32767999;   // TS Add here.

 return caps.max_adj;
}

Thanks,
Takahiro Shimizu