[Linuxptp-devel] [PATCH v4] phc2sys: Add support for free-running mode

[Maciek Machnikowski]

Add support for the free-running mode that will not adjust the sink
clock when enabled.

V2: changed implementation to instantiate NTPSHM servo that serves as
    the nochange servo
V3: revert to original implementation and remove unused global
V4: fix uninitialized ppb variable in update_clock()

Signed-off-by: Maciek Machnikowski <mac...@machnikowski.net>
---
 phc2sys.8 |  4 ++++
 phc2sys.c | 15 +++++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/phc2sys.8 b/phc2sys.8
index 9277e01..963df83 100644
--- a/phc2sys.8
+++ b/phc2sys.8
@@ -323,6 +323,10 @@ Same as option
 .B \-E
 (see above).
 
+.TP
+.B free-running
+Don't adjust the sink clock if enabled. The default is 0 (disabled).
+
 .TP
 .B transportSpecific
 The transport specific field. Must be in the range 0 to 255.
diff --git a/phc2sys.c b/phc2sys.c
index fbbe5b4..63ec6d5 100644
--- a/phc2sys.c
+++ b/phc2sys.c
@@ -103,6 +103,7 @@ struct phc2sys_private {
        int forced_sync_offset;
        int kernel_leap;
        int state_changed;
+       int free_running;
        struct pmc_agent *agent;
        LIST_HEAD(port_head, port) ports;
        LIST_HEAD(clock_head, clock) clocks;
@@ -129,7 +130,8 @@ static struct servo *servo_add(struct phc2sys_private *priv,
        ppb = clockadj_get_freq(clock->clkid);
        /* The reading may silently fail and return 0, reset the frequency to
           make sure ppb is the actual frequency of the clock. */
-       clockadj_set_freq(clock->clkid, ppb);
+       if (!priv->free_running)
+               clockadj_set_freq(clock->clkid, ppb);
        if (clock->clkid == CLOCK_REALTIME) {
                sysclk_set_leap(0);
                max_ppb = sysclk_max_freq();
@@ -530,8 +532,8 @@ static void update_clock_stats(struct clock *clock, 
unsigned int max_count,
 static void update_clock(struct phc2sys_private *priv, struct clock *clock,
                         int64_t offset, uint64_t ts, int64_t delay)
 {
-       enum servo_state state;
-       double ppb;
+       enum servo_state state = SERVO_UNLOCKED;
+       double ppb = 0.0;
 
        if (!clock->servo) {
                clock->servo = servo_add(priv, clock);
@@ -544,6 +546,9 @@ static void update_clock(struct phc2sys_private *priv, 
struct clock *clock,
 
        offset += get_sync_offset(priv, clock);
 
+       if (priv->free_running)
+               goto report;
+
        if (clock->sanity_check && clockcheck_sample(clock->sanity_check, ts))
                servo_reset(clock->servo);
 
@@ -568,6 +573,7 @@ static void update_clock(struct phc2sys_private *priv, 
struct clock *clock,
                break;
        }
 
+report:
        if (clock->offset_stats) {
                update_clock_stats(clock, priv->stats_max_count, offset, ppb, 
delay);
        } else {
@@ -1305,8 +1311,9 @@ int main(int argc, char *argv[])
        print_set_syslog(config_get_int(cfg, NULL, "use_syslog"));
        print_set_level(config_get_int(cfg, NULL, "logging_level"));
 
+       priv.free_running = config_get_int(cfg, NULL, "free_running");
        priv.servo_type = config_get_int(cfg, NULL, "clock_servo");
-       if (priv.servo_type == CLOCK_SERVO_NTPSHM) {
+       if (priv.free_running || priv.servo_type == CLOCK_SERVO_NTPSHM) {
                config_set_int(cfg, "kernel_leap", 0);
                config_set_int(cfg, "sanity_freq_limit", 0);
        }
-- 
2.31.1



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