From 4545fd1150964b15adb93adcacb64f3fc18991aa Mon Sep 17 00:00:00 2001
From: Richard Cochran <richardcochran@gmail.com>
Date: Tue, 14 Feb 2017 20:03:15 +0100
Subject: [PATCH] telecom: Add a configuration option for
 G.8275.portDS.localPriority.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
---
 config.c       |  1 +
 default.cfg    |  1 +
 gPTP.cfg       |  1 +
 port.c         |  3 ++-
 port_private.h |  1 +
 ptp4l.8        | 15 +++++++++++++++
 6 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/config.c b/config.c
index 9c26ccd..f75092e 100644
--- a/config.c
+++ b/config.c
@@ -193,6 +193,7 @@ struct config_item config_tab[] = {
 	GLOB_ITEM_INT("free_running", 0, 0, 1),
 	PORT_ITEM_INT("freq_est_interval", 1, 0, INT_MAX),
 	GLOB_ITEM_INT("G.8275.defaultDS.localPriority", 128, 1, UINT8_MAX),
+	PORT_ITEM_INT("G.8275.portDS.localPriority", 128, 1, UINT8_MAX),
 	GLOB_ITEM_INT("gmCapable", 1, 0, 1),
 	PORT_ITEM_INT("hybrid_e2e", 0, 0, 1),
 	PORT_ITEM_INT("ignore_transport_specific", 0, 0, 1),
diff --git a/default.cfg b/default.cfg
index 9736568..24836dd 100644
--- a/default.cfg
+++ b/default.cfg
@@ -28,6 +28,7 @@ syncReceiptTimeout	0
 delayAsymmetry		0
 fault_reset_interval	4
 neighborPropDelayThresh	20000000
+G.8275.portDS.localPriority	128
 #
 # Run time options
 #
diff --git a/gPTP.cfg b/gPTP.cfg
index 02fd395..095a444 100644
--- a/gPTP.cfg
+++ b/gPTP.cfg
@@ -26,6 +26,7 @@ delayAsymmetry		0
 fault_reset_interval	4
 neighborPropDelayThresh	800
 min_neighbor_prop_delay	-20000000
+G.8275.portDS.localPriority	128
 #
 # Run time options
 #
diff --git a/port.c b/port.c
index fc65153..3279417 100644
--- a/port.c
+++ b/port.c
@@ -77,7 +77,7 @@ static void announce_to_dataset(struct ptp_message *m, struct port *p,
 	out->identity     = a->grandmasterIdentity;
 	out->quality      = a->grandmasterClockQuality;
 	out->priority2    = a->grandmasterPriority2;
-	out->localPriority = 128;
+	out->localPriority = p->localPriority;
 	out->stepsRemoved = a->stepsRemoved;
 	out->sender       = m->header.sourcePortIdentity;
 	out->receiver     = p->portIdentity;
@@ -1568,6 +1568,7 @@ int port_initialize(struct port *p)
 	p->transportSpecific       = config_get_int(cfg, p->name, "transportSpecific");
 	p->transportSpecific     <<= 4;
 	p->match_transport_specific = !config_get_int(cfg, p->name, "ignore_transport_specific");
+	p->localPriority           = config_get_int(cfg, p->name, "G.8275.portDS.localPriority");
 	p->logSyncInterval         = config_get_int(cfg, p->name, "logSyncInterval");
 	p->logMinPdelayReqInterval = config_get_int(cfg, p->name, "logMinPdelayReqInterval");
 	p->neighborPropDelayThresh = config_get_int(cfg, p->name, "neighborPropDelayThresh");
diff --git a/port_private.h b/port_private.h
index f8771c7..436e7b7 100644
--- a/port_private.h
+++ b/port_private.h
@@ -100,6 +100,7 @@ struct port {
 	int                 announce_span;
 	UInteger8           syncReceiptTimeout;
 	UInteger8           transportSpecific;
+	UInteger8           localPriority;
 	Integer8            logSyncInterval;
 	Enumeration8        delayMechanism;
 	Integer8            logMinPdelayReqInterval;
diff --git a/ptp4l.8 b/ptp4l.8
index 10f55f2..11e3cc0 100644
--- a/ptp4l.8
+++ b/ptp4l.8
@@ -245,6 +245,21 @@ The default is UDPv4.
 Upper limit for peer delay in nanoseconds. If the estimated peer delay is
 greater than this value the port is marked as not 802.1AS capable.
 .TP
+.B G.8275.portDS.localPriority
+The Telecom Profiles (ITU-T G.8275.1 and G.8275.2) specify an
+alternate Best Master Clock Algorithm (BMCA) with a unique data set
+comparison algorithm.  The value of this option is associated with
+Announce messages arriving on a particular port and is used as a tie
+breaker whenever clockClass, clockAccuracy, offsetScaledLogVariance,
+and priority2 are equal. This option is only used when
+"dataset_comparison" is set to "telecom".
+The default value is 128.
+
+Warning: the BMCA is guaranteed to produce a spanning tree (that is, a
+timing network without loops) only when using the default values of
+G.8275.defaultDS.localPriority and G.8275.portDS.localPriority.
+Careful network engineering is needed when using non-default values.
+.TP
 .B min_neighbor_prop_delay
 Lower limit for peer delay in nanoseconds. If the estimated peer delay is
 smaller than this value the port is marked as not 802.1AS capable.