commit ac92a711614c413b75a4963eab95cd1aa2de8293

Author: Miroslav Lichvar <mlichvar@redhat.com>

Date:   Mon Mar 27 17:43:06 2017 +0200

    phc2sys: don't synchronize clock to itself.

    When ptp4l is using multiple interfaces sharing the same clock, phc2sys

    in the automatic mode should not try to synchronize them to each other.

    Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>

    Reported-by: Stefan Lange <s.lange@gateware.de>

diff --git a/phc2sys.c b/phc2sys.c

index aa4186b..4c8b552 100644

--- a/phc2sys.c

+++ b/phc2sys.c

@@ -72,6 +72,7 @@

 struct clock {

 	LIST_ENTRY(clock) list;

 	clockid_t clkid;

+	int phc_index;

 	int sysoff_supported;

 	int is_utc;

 	int dest_only;

@@ -127,7 +128,7 @@ static int clock_handle_leap(struct node *node, struct clock *clock,

 static int run_pmc_get_utc_offset(struct node *node, int timeout);

 static void run_pmc_events(struct node *node);

-static clockid_t clock_open(char *device)

+static clockid_t clock_open(char *device, int *phc_index)

 {

 	struct sk_ts_info ts_info;

 	char phc_device[16];

@@ -157,6 +158,7 @@ static clockid_t clock_open(char *device)

 	clkid = phc_open(phc_device);

 	if (clkid == CLOCK_INVALID)

 		fprintf(stderr, "cannot open %s: %m\n", device);

+	*phc_index = ts_info.phc_index;

 	return clkid;

 }

@@ -164,11 +166,11 @@ static struct clock *clock_add(struct node *node, char *device)

 {

 	struct clock *c;

 	clockid_t clkid = CLOCK_INVALID;

-	int max_ppb;

+	int max_ppb, phc_index = -1;

 	double ppb;

 	if (device) {

-		clkid = clock_open(device);

+		clkid = clock_open(device, &phc_index);

 		if (clkid == CLOCK_INVALID)

 			return NULL;

 	}

@@ -179,6 +181,7 @@ static struct clock *clock_add(struct node *node, char *device)

 		return NULL;

 	}

 	c->clkid = clkid;

+	c->phc_index = phc_index;

 	c->servo_state = SERVO_UNLOCKED;

 	c->device = strdup(device);

@@ -638,6 +641,13 @@ static int do_loop(struct node *node, int subscriptions)

 			if (!update_needed(clock))

 				continue;

+			/* don't try to synchronize the clock to itself */

+			if (clock->clkid == node->master->clkid ||

+			    (clock->phc_index >= 0 &&

+			     clock->phc_index == node->master->phc_index) ||

+			    !strcmp(clock->device, node->master->device))

+				continue;

+

 			if (clock->clkid == CLOCK_REALTIME &&

 			    node->master->sysoff_supported) {

 				/* use sysoff */