Re: [Linuxptp-users] Synchronization fault with stmmac

[Richard C. <ric...@gm...>]

On Tue, Mar 25, 2014 at 12:30:01PM +0100, Richard Cochran wrote:
> On Tue, Mar 25, 2014 at 09:52:32AM +0100, Mohamed Belaouad wrote:
> 
> > Also, what we would like to know is: is the max ppb adjustment check
> > done in the PTP subsystem (I have not found anything about it in
> > drivers/ptp, maybe wrong location?) or should it be handled in the
> > driver?
> 
> There is no check in the kernel. I guess that ptp_clock_adjtime could
> return ERANGE in such a case.

Is this (untested patch) what you are asking for?

Thanks,
Richard
---
diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index e25d2bc..239d02f 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -142,7 +142,10 @@ static int ptp_clock_adjtime(struct posix_clock *pc, struct timex *tx)
 		delta = ktime_to_ns(kt);
 		err = ops->adjtime(ops, delta);
 	} else if (tx->modes & ADJ_FREQUENCY) {
-		err = ops->adjfreq(ops, scaled_ppm_to_ppb(tx->freq));
+		s32 delta = scaled_ppm_to_ppb(tx->freq);
+		if (delta > ops->max_adj || delta < -ops->max_adj)
+			return -ERANGE;
+		err = ops->adjfreq(ops, delta);
 		ptp->dialed_frequency = tx->freq;
 	} else if (tx->modes == 0) {
 		tx->freq = ptp->dialed_frequency;