Current implementation of flag "-a -rr" for phc2sys selects CLOCK_REALTIME for
both directions of PTP synchronization. This may be impractical for Network
Time Servers which use alternative sources of synchronization, that usually
have clock adjusted by ntpd/chrony.
For gPTP Grandmaster in Time Servers the most optimal solution would be to
use CLOCK_REALTIME to synchronize phc when in Master state and stopping
synchronization when in Slave state. This would allow to combine
internal Time Server sources (using ntpd/chrony) with phc as Master/Slave.
Implementation of two-way gPTP synchronization requires two phc2sys instances:
- one synchronizing CLOCK_REALTIME->phc when in Master (phc2sys -a -rr),
- second synchronizing phc->ntpshm when in Slave state (phc2sys -a -r -E
ntpshm).
The problem is that current implementation of autoconfiguration in gPTP will
synchronize phc from CLOCK_REALTIME when in Slave state.
To address this issue, the additional (triple) '-r' flag was implemented.
When using '-a -rrr' CLOCK_REALTIME will be used as "source only".
This is probably better solution than usage of separate program detecting
current portState of PTP.
Signed-off-by: Jakub Raczynski <j.raczyn...@elpromaelectronics.com>
---
phc2sys.8 | 5 ++++-
phc2sys.c | 22 ++++++++++++++++++++--
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/phc2sys.8 b/phc2sys.8
index 963df83..3858c22 100644
--- a/phc2sys.8
+++ b/phc2sys.8
@@ -75,7 +75,10 @@ to also synchronize the system clock (CLOCK_REALTIME). By
default, the
system clock is not considered as a possible time source. If you want the
system clock to be eligible to become a time source, specify the
.B \-r
-option twice.
+option twice. Specify
+.B \-r
+thrice to use CLOCK_REALTIME as source only and do not synchronize it to
+other sources.
.TP
.BI \-f " config"
Read configuration from the specified file. No configuration file is read by
diff --git a/phc2sys.c b/phc2sys.c
index 2c8e905..ab0376a 100644
--- a/phc2sys.c
+++ b/phc2sys.c
@@ -72,6 +72,7 @@ struct clock {
int sysoff_method;
int is_utc;
int dest_only;
+ int src_only;
int state;
int new_state;
int sync_offset;
@@ -468,12 +469,16 @@ static void reconfigure(struct phc2sys_private *priv)
src = rt;
rt->state = PS_SLAVE;
} else if (rt) {
- if (rt->state != PS_MASTER) {
+ if (rt->state != PS_MASTER && !rt->src_only) {
rt->state = PS_MASTER;
clock_reinit(priv, rt, rt->state);
}
LIST_INSERT_HEAD(&priv->dst_clocks, rt, dst_list);
pr_info("selecting %s for synchronization", rt->device);
+ if (rt && rt->src_only && rt->state != PS_MASTER) {
+ pr_info("clock %s selected as source only, not
synchronizing",
+ rt->device);
+ }
}
priv->master = src;
pr_info("selecting %s as the master clock", src->device);
@@ -895,8 +900,21 @@ static int auto_init_ports(struct phc2sys_private *priv,
int add_rt)
clock = clock_add(priv, "CLOCK_REALTIME", -1);
if (!clock)
return -1;
- if (add_rt == 1)
+ switch (add_rt) {
+ case 1:
+ default:
clock->dest_only = 1;
+ clock->src_only = 0;
+ break;
+ case 2:
+ clock->dest_only = 0;
+ clock->src_only = 0;
+ break;
+ case 3:
+ clock->dest_only = 0;
+ clock->src_only = 1;
+ break;
+ }
}
/* get initial offset */
--
2.25.1
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