wr-servo: loose track_phase when big offset

Even if we count failure events for SNMP (in the switch), we actually never generate them. The code has always been tracking phase for any offset smaller than one clock tick (8ns or 16ns), but we'd better jump in phase (and leave TRACK_PHASE servo state) and this is a failure. With this commit, to loos track_phase in wrpc you can just force the setpoint far enough from the calculated one: e.g. [..] cko:2 setp:929 [...] wrc# pll sps 0 500 [...] ss:'SYNC_PHASE' [...] cko:431 setp:1367 [...] then it takes 15 iterations to converge, but that's because the calculations the first time (as shown) are wrong. A real glitch loosing track_phase would be recovered in 3 iterations. Signed-off-by: Alessandro Rubini <rubini@gnudd.com>

wr-servo: loose track_phase when big offset
Even if we count failure events for SNMP (in the switch), we actually never generate them. The code has always been tracking phase for any offset smaller than one clock tick (8ns or 16ns), but we'd better jump in phase (and leave TRACK_PHASE servo state) and this is a failure. With this commit, to loos track_phase in wrpc you can just force the setpoint far enough from the calculated one: e.g. [..] cko:2 setp:929 [...] wrc# pll sps 0 500 [...] ss:'SYNC_PHASE' [...] cko:431 setp:1367 [...] then it takes 15 iterations to converge, but that's because the calculations the first time (as shown) are wrong. A real glitch loosing track_phase would be recovered in 3 iterations. Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
5c5c8039 · Alessandro Rubini · 1d2c640d · 5c5c8039
Commit 5c5c8039 authored Feb 17, 2016 by Alessandro Rubini
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wr-servo.c proto-ext-whiterabbit/wr-servo.c +6 -0

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--- a/proto-ext-whiterabbit/wr-servo.c
+++ b/proto-ext-whiterabbit/wr-servo.c
@@ -393,6 +393,12 @@ int wr_servo_update(struct pp_instance *ppi)

 		/* Can be disabled for manually tweaking and testing */
 		if(tracking_enabled) {
+			if (abs(ts_offset_hw.phase) >
+			    2 * WR_SERVO_OFFSET_STABILITY_THRESHOLD) {
+				s->state = WR_SYNC_PHASE;
+				break;
+			}
+
 			// adjust phase towards offset = 0 make ck0 0
 			s->cur_setpoint += (ts_offset_hw.phase / 4);