[Linuxptp-devel] [PATCH RFC 5/7] port: Check for virtual clocks.

[Miroslav L. <mli...@re...>]

If the PHC specified with the phc_index or -p option is a virtual clock
of the interface, bind sockets to the virtual clock instead of the real
clock to get correct timestamps.

Signed-off-by: Miroslav Lichvar <mli...@re...>
---
 port.c  | 7 ++++++-
 ptp4l.8 | 3 +++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/port.c b/port.c
index a84ba66..5a5741d 100644
--- a/port.c
+++ b/port.c
@@ -3133,7 +3133,12 @@ struct port *port_open(const char *phc_device,
 		pr_warning("%s: get_ts_info not supported", p->log_name);
 	} else if (p->phc_index >= 0 &&
 		   p->phc_index != interface_phc_index(interface)) {
-		if (p->jbod) {
+		if (rtnl_iface_has_vclock(interface_name(interface),
+					  p->phc_index)) {
+			pr_info("%s: /dev/ptp%d is virtual clock",
+				p->log_name, p->phc_index);
+			interface_set_vclock(interface, phc_index);
+		} else if (p->jbod) {
 			pr_warning("%s: just a bunch of devices", p->log_name);
 			p->phc_index = interface_phc_index(interface);
 		} else if (phc_device) {
diff --git a/ptp4l.8 b/ptp4l.8
index 1d6f078..e53fcc4 100644
--- a/ptp4l.8
+++ b/ptp4l.8
@@ -377,6 +377,9 @@ The default is 0 (disabled).
 .TP
 .B phc_index
 Specifies the index of the PHC to be used for synchronization and timestamping.
+This option is useful with Linux kernels 5.17 and later, which allow multiple
+virtual clocks to be created on top of a free-running hardware clock by writing
+to /sys/class/ptp/ptp*/n_vclocks.
 The default is -1, which means the index will be set to the PHC associated with
 the interface, or the device specified by the \fB-p\fP option.
 .TP
-- 
2.33.1