Fix the port finite state machine.

The state machine needs to know whether a new master has just been
selected in order to choose between the slave and uncalibrated states.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>

clock.c

@@ -230,7 +230,7 @@ struct clock *clock_create(char *phc, struct interface *iface, int count,
 	c->dds.numberPorts = c->nports = count;
 
 	for (i = 0; i < c->nports; i++)
-		port_dispatch(c->port[i], EV_INITIALIZE);
+		port_dispatch(c->port[i], EV_INITIALIZE, 0);
 
 	return c;
 }
@@ -322,7 +322,7 @@ int clock_poll(struct clock *c)
 				if (EV_STATE_DECISION_EVENT == event)
 					sde = 1;
 				else
-					port_dispatch(c->port[i], event);
+					port_dispatch(c->port[i], event, 0);
 			}
 		}
 	}
@@ -435,7 +435,7 @@ struct timePropertiesDS *clock_time_properties(struct clock *c)
 static void handle_state_decision_event(struct clock *c)
 {
 	struct foreign_clock *best = NULL, *fc;
-	int i;
+	int fresh_best = 0, i;
 
 	for (i = 0; i < c->nports; i++) {
 		fc = port_compute_best(c->port[i]);
@@ -451,8 +451,10 @@ static void handle_state_decision_event(struct clock *c)
 	pr_notice("selected best master clock %s",
 		cid2str(&best->dataset.identity));
 
-	if (c->best != best)
+	if (c->best != best) {
 		mave_reset(c->avg_delay);
+		fresh_best = 1;
+	}
 
 	c->best = best;
 
@@ -482,6 +484,6 @@ static void handle_state_decision_event(struct clock *c)
 			event = EV_INITIALIZE;
 			break;
 		}
-		port_dispatch(c->port[i], event);
+		port_dispatch(c->port[i], event, fresh_best);
 	}
 }

fsm.c

@@ -18,7 +18,7 @@
  */
 #include "fsm.h"
 
-enum port_state ptp_fsm(enum port_state state, enum fsm_event event)
+enum port_state ptp_fsm(enum port_state state, enum fsm_event event, int mdiff)
 {
 	enum port_state next = state;
 
@@ -195,7 +195,8 @@ enum port_state ptp_fsm(enum port_state state, enum fsm_event event)
 			next = PS_GRAND_MASTER;
 			break;
 		case EV_RS_SLAVE:
-			next = PS_UNCALIBRATED;
+			if (mdiff)
+				next = PS_UNCALIBRATED;
 			break;
 		case EV_RS_PASSIVE:
 			next = PS_PASSIVE;
@@ -209,7 +210,8 @@ enum port_state ptp_fsm(enum port_state state, enum fsm_event event)
 	return next;
 }
 
-enum port_state ptp_slave_fsm(enum port_state state, enum fsm_event event)
+enum port_state ptp_slave_fsm(enum port_state state, enum fsm_event event,
+			      int mdiff)
 {
 	enum port_state next = state;
 
@@ -301,7 +303,8 @@ enum port_state ptp_slave_fsm(enum port_state state, enum fsm_event event)
 			next = PS_UNCALIBRATED;
 			break;
 		case EV_RS_SLAVE:
-			next = PS_UNCALIBRATED;
+			if (mdiff)
+				next = PS_UNCALIBRATED;
 			break;
 		default:
 			break;

fsm.h

@@ -58,16 +58,19 @@ enum fsm_event {
  * Run the state machine for a BC or OC port.
  * @param state  The current state of the port.
  * @param event  The event to be processed.
+ * @param mdiff  Whether a new master has been selected.
  * @return       The new state for the port.
  */
-enum port_state ptp_fsm(enum port_state state, enum fsm_event event);
+enum port_state ptp_fsm(enum port_state state, enum fsm_event event, int mdiff);
 
 /**
  * Run the state machine for a slave only clock.
  * @param state  The current state of the port.
  * @param event  The event to be processed.
+ * @param mdiff  Whether a new master has been selected.
  * @return       The new state for the port.
  */
-enum port_state ptp_slave_fsm(enum port_state state, enum fsm_event event);
+enum port_state ptp_slave_fsm(enum port_state state, enum fsm_event event,
+			      int mdiff);
 
 #endif

port.c

@@ -311,10 +311,10 @@ static void port_synchronize(struct port *p,
 	switch (state) {
 	case SERVO_UNLOCKED:
 	case SERVO_JUMP:
-		port_dispatch(p, EV_SYNCHRONIZATION_FAULT);
+		port_dispatch(p, EV_SYNCHRONIZATION_FAULT, 0);
 		break;
 	case SERVO_LOCKED:
-		port_dispatch(p, EV_MASTER_CLOCK_SELECTED);
+		port_dispatch(p, EV_MASTER_CLOCK_SELECTED, 0);
 		break;
 	}
 }
@@ -794,10 +794,11 @@ struct foreign_clock *port_compute_best(struct port *p)
 	return p->best;
 }
 
-void port_dispatch(struct port *p, enum fsm_event event)
+void port_dispatch(struct port *p, enum fsm_event event, int mdiff)
 {
 	enum port_state next = clock_slave_only(p->clock) ?
-		ptp_slave_fsm(p->state, event) : ptp_fsm(p->state, event);
+		ptp_slave_fsm(p->state, event, mdiff) :
+		ptp_fsm(p->state, event, mdiff);
 
 	if (PS_INITIALIZING == next) {
 		/*

port.h

@@ -69,8 +69,9 @@ struct foreign_clock *port_compute_best(struct port *port);
  *
  * @param port A pointer previously obtained via port_open().
  * @param event One of the @a fsm_event codes.
+ * @param mdiff Whether a new master has been selected.
  */
-void port_dispatch(struct port *port, enum fsm_event event);
+void port_dispatch(struct port *p, enum fsm_event event, int mdiff);
 
 /**
  * Generates state machine events based on activity on a port's file