> -----Original Message-----
> From: Miroslav Lichvar [mailto:mlich...@redhat.com]
> Sent: Monday, November 12, 2018 8:28 AM
> To: linuxptp-devel@lists.sourceforge.net
> Subject: [Linuxptp-devel] [PATCH 2/6] sysoff: Extend API for different sysoff
> methods.
>
> The kernel supports different PTP_SYS_OFFSET* ioctls. Use the sysoff
> enum to allow selecting between them in sysoff_measure().
>
> Signed-off-by: Miroslav Lichvar <mlich...@redhat.com>
> ---
> phc2sys.c | 12 ++++++------
> phc_ctl.c | 8 +++++---
> sysoff.c | 25 +++++++++++++++++++++----
> sysoff.h | 12 +++++++-----
> 4 files changed, 39 insertions(+), 18 deletions(-)
>
> diff --git a/phc2sys.c b/phc2sys.c
> index 15f8d75..2cd477a 100644
> --- a/phc2sys.c
> +++ b/phc2sys.c
> @@ -74,7 +74,7 @@ struct clock {
> LIST_ENTRY(clock) dst_list;
> clockid_t clkid;
> int phc_index;
> - int sysoff_supported;
> + int sysoff_method;
> int is_utc;
> int dest_only;
> int state;
> @@ -255,9 +255,8 @@ static struct clock *clock_add(struct node *node, char
> *device)
> c->servo = servo_add(node, c);
>
> if (clkid != CLOCK_INVALID && clkid != CLOCK_REALTIME)
> - c->sysoff_supported = (SYSOFF_SUPPORTED ==
> - sysoff_probe(CLOCKID_TO_FD(clkid),
> - node->phc_readings));
> + c->sysoff_method = sysoff_probe(CLOCKID_TO_FD(clkid),
> + node->phc_readings);
>
> LIST_INSERT_HEAD(&node->clocks, c, list);
> return c;
> @@ -784,11 +783,12 @@ static int do_loop(struct node *node, int subscriptions)
> continue;
>
> if (clock->clkid == CLOCK_REALTIME &&
> - node->master->sysoff_supported) {
> + node->master->sysoff_method >= 0) {
> /* use sysoff */
> if (sysoff_measure(CLOCKID_TO_FD(node->master-
> >clkid),
> + node->master->sysoff_method,
> node->phc_readings,
> - &offset, &ts, &delay))
> + &offset, &ts, &delay) < 0)
> return -1;
> } else {
> /* use phc */
> diff --git a/phc_ctl.c b/phc_ctl.c
> index 4a78a19..b9a9cf4 100644
> --- a/phc_ctl.c
> +++ b/phc_ctl.c
> @@ -367,10 +367,12 @@ static int do_cmp(clockid_t clkid, int cmdc, char
> *cmdv[])
> struct timespec ts, rta, rtb;
> int64_t sys_offset, delay = 0, offset;
> uint64_t sys_ts;
> + int method;
>
> - if (SYSOFF_SUPPORTED ==
> - sysoff_measure(CLOCKID_TO_FD(clkid),
> - 9, &sys_offset, &sys_ts, &delay)) {
> + method = sysoff_probe(CLOCKID_TO_FD(clkid), 9);
> +
> + if (method >= 0 && sysoff_measure(CLOCKID_TO_FD(clkid), method, 9,
> + &sys_offset, &sys_ts, &delay) >= 0) {
> pr_notice( "offset from CLOCK_REALTIME is %"PRId64"ns\n",
> sys_offset);
> return 0;
> diff --git a/sysoff.c b/sysoff.c
> index 407a01c..f709a9b 100644
> --- a/sysoff.c
> +++ b/sysoff.c
> @@ -73,8 +73,8 @@ static int64_t sysoff_estimate(struct ptp_clock_time *pct,
> int
> n_samples,
> return samples[0].offset;
> }
>
> -int sysoff_measure(int fd, int n_samples,
> - int64_t *result, uint64_t *ts, int64_t *delay)
> +static int sysoff_basic(int fd, int n_samples,
> + int64_t *result, uint64_t *ts, int64_t *delay)
> {
> struct ptp_sys_offset pso;
> memset(&pso, 0, sizeof(pso));
> @@ -84,13 +84,24 @@ int sysoff_measure(int fd, int n_samples,
> return SYSOFF_RUN_TIME_MISSING;
> }
> *result = sysoff_estimate(pso.ts, n_samples, ts, delay);
> - return SYSOFF_SUPPORTED;
> + return SYSOFF_BASIC;
> +}
> +
> +int sysoff_measure(int fd, int method, int n_samples,
> + int64_t *result, uint64_t *ts, int64_t *delay)
> +{
> + switch (method) {
> + case SYSOFF_BASIC:
> + return sysoff_basic(fd, n_samples, result, ts, delay);
> + }
> + return SYSOFF_COMPILE_TIME_MISSING;
> }
>
> int sysoff_probe(int fd, int n_samples)
> {
> int64_t junk, delay;
> uint64_t ts;
> + int i;
>
> if (n_samples > PTP_MAX_SAMPLES) {
> fprintf(stderr, "warning: %d exceeds kernel max readings %d\n",
> @@ -99,7 +110,13 @@ int sysoff_probe(int fd, int n_samples)
> return SYSOFF_RUN_TIME_MISSING;
> }
>
> - return sysoff_measure(fd, n_samples, &junk, &ts, &delay);
> + for (i = 0; i < SYSOFF_LAST; i++) {
> + if (sysoff_measure(fd, i, n_samples, &junk, &ts, &delay) < 0)
> + continue;
> + return i;
> + }
Aha! It took me a while when reading the code to figure out where we probed the
best method. So here, we scan from 0 to SYSOFF_LAST, and then return the first
one that succeeds. Ok.
That means that we want to order the non-zero values such that the better
choices are lower numbers. I think that means we should have SYSOFF_PRECISE
first, then SYSOFF_EXTENDED, and then SYSOFF_BASIC.
This seems to match what you added in patch 4. Excellent.
Thanks,
Jake
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