[Linuxptp-devel] [PATCHv2 RFC] phc2sys: don't synchronize clock to itself.

[Miroslav Lichvar]

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 <***@redhat.com>
---
phc2sys.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

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 */