From: Vincent Cheng <vincent.cheng...@renesas.com>
When clock stepping is unable to happen instantaneously the subsequent
timestamps after a clock step does not reflect the step result and
undesired clock freq and step adjustments will occur.
When using ts2phc to synchronize timestamping clock using external
1 PPS, it could take up to 1 second for the timestamps to reflect the
clock step.
step_window, when set, indicates the number of Sync events after a
clock step in which the clock servo will not do any frequency or
step adjustments.
Signed-off-by: Vincent Cheng <vincent.cheng...@renesas.com>
---
clock.c | 17 +++++++++++++++++
config.c | 1 +
ptp4l.8 | 8 ++++++++
3 files changed, 26 insertions(+)
diff --git a/clock.c b/clock.c
index a66d189..783a241 100644
--- a/clock.c
+++ b/clock.c
@@ -132,6 +132,8 @@ struct clock {
struct interface *udsif;
LIST_HEAD(clock_subscribers_head, clock_subscriber) subscribers;
struct monitor *slave_event_monitor;
+ int step_window;
+ int step_window_counter;
};
struct clock the_clock;
@@ -1193,6 +1195,9 @@ struct clock *clock_create(enum clock_type type, struct
config *config,
return NULL;
}
+ c->step_window = config_get_int(config, NULL, "step_window");
+ c->step_window_counter = 0;
+
/* Create the ports. */
STAILQ_FOREACH(iface, &config->interfaces, list) {
if (clock_add_port(c, phc_device, phc_index, timestamping,
iface)) {
@@ -1695,6 +1700,15 @@ int clock_switch_phc(struct clock *c, int phc_index)
return 0;
}
+static void clock_step_window(struct clock *c)
+{
+ if (!c->step_window)
+ return;
+
+ c->step_window_counter = c->step_window;
+ c->free_running = 1;
+}
+
static void clock_synchronize_locked(struct clock *c, double adj)
{
clockadj_set_freq(c->clkid, -adj);
@@ -1731,6 +1745,8 @@ enum servo_state clock_synchronize(struct clock *c, tmv_t
ingress, tmv_t origin)
c->cur.offsetFromMaster = tmv_to_TimeInterval(c->master_offset);
if (c->free_running) {
+ if (c->step_window && !(--c->step_window_counter))
+ c->free_running = 0;
return clock_no_adjust(c, ingress, origin);
}
@@ -1747,6 +1763,7 @@ enum servo_state clock_synchronize(struct clock *c, tmv_t
ingress, tmv_t origin)
case SERVO_JUMP:
clockadj_set_freq(c->clkid, -adj);
clockadj_step(c->clkid, -tmv_to_nanoseconds(c->master_offset));
+ clock_step_window(c);
c->ingress_ts = tmv_zero();
if (c->sanity_check) {
clockcheck_set_freq(c->sanity_check, -adj);
diff --git a/config.c b/config.c
index d237de9..65be360 100644
--- a/config.c
+++ b/config.c
@@ -302,6 +302,7 @@ struct config_item config_tab[] = {
GLOB_ITEM_INT("slaveOnly", 0, 0, 1),
GLOB_ITEM_INT("socket_priority", 0, 0, 15),
GLOB_ITEM_DBL("step_threshold", 0.0, 0.0, DBL_MAX),
+ GLOB_ITEM_INT("step_window", 0, 0, INT_MAX),
GLOB_ITEM_INT("summary_interval", 0, INT_MIN, INT_MAX),
PORT_ITEM_INT("syncReceiptTimeout", 0, 0, UINT8_MAX),
GLOB_ITEM_INT("tc_spanning_tree", 0, 0, 1),
diff --git a/ptp4l.8 b/ptp4l.8
index b179b81..66504ef 100644
--- a/ptp4l.8
+++ b/ptp4l.8
@@ -694,6 +694,14 @@ one-second offset slowly by changing the clock frequency
(unless the
option is set to correct such offset by stepping).
Relevant only with software time stamping. The default is 1 (enabled).
.TP
+.B step_window
+When set, indicates the number of Sync events after a clock step that
+the clock will not do any frequency or step adjustments.
+This is used in situations where clock stepping is unable to happen
+instantaneously so there is a lag before the timestamps can settle
+properly to reflect the clock step.
+The default is 0 (disabled).
+.TP
.B timeSource
The time source is a single byte code that gives an idea of the kind
of local clock in use. The value is purely informational, having no
--
2.7.4
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