phc2sys: don't zero clock frequency on start.
Instead of always starting at zero frequency offset, read the currently stored value on start and pass it to the servo. As the read may silently fail and return zero, set the clock frequency back to the read value to make sure it's always equal to the actual frequency of the clock. Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>master
parent
2d4b2f1640
commit
fc1a695493
20
phc2sys.c
20
phc2sys.c
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@ -76,6 +76,18 @@ static void clock_ppb(clockid_t clkid, double ppb)
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fprintf(stderr, "failed to adjust the clock: %m\n");
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}
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static double clock_ppb_read(clockid_t clkid)
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{
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double f = 0.0;
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struct timex tx;
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memset(&tx, 0, sizeof(tx));
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if (clock_adjtime(clkid, &tx) < 0)
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fprintf(stderr, "failed to read out the clock frequency adjustment: %m\n");
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else
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f = tx.freq / 65.536;
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return f;
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}
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static void clock_step(clockid_t clkid, int64_t ns)
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{
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struct timex tx;
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@ -271,6 +283,7 @@ int main(int argc, char *argv[])
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char *device = NULL, *progname, *ethdev = NULL;
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clockid_t src = CLOCK_INVALID;
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int c, phc_readings = 5, phc_rate = 1, sync_offset = 0;
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double ppb;
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struct clock dst_clock = {
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.clkid = CLOCK_REALTIME,
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.log_file = stdout
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@ -351,9 +364,12 @@ int main(int argc, char *argv[])
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perror("clock_settime");
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}
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clock_ppb(dst_clock.clkid, 0.0);
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ppb = clock_ppb_read(dst_clock.clkid);
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/* The reading may silently fail and return 0, reset the frequency to
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make sure ppb is the actual frequency of the clock. */
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clock_ppb(dst_clock.clkid, ppb);
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dst_clock.servo = servo_create(CLOCK_SERVO_PI, 0.0, max_ppb, 0);
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dst_clock.servo = servo_create(CLOCK_SERVO_PI, -ppb, max_ppb, 0);
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if (device)
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return do_pps_loop(&dst_clock, device);
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