From 09e5e6e934814a0ce3528822a35b7f89b0ce8e11 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Tue, 10 Feb 2015 16:54:43 +0100
Subject: [PATCH] phc2sys: don't synchronize clock to itself in automatic mode.

When no source is found in the automatic mode and a clock is selected as
the default source, set its state temporarily to slave to prevent the
clock from being synchronized to itself and drifting quickly away.

Also, don't use this mode with only one PTP clock and don't include the
system clock.

This fixes phc2sys with SHM servo (e.g. used by timemaster).
---
 phc2sys.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/phc2sys.c b/phc2sys.c
index d59814d..23993ac 100644
--- a/phc2sys.c
+++ b/phc2sys.c
@@ -332,9 +332,14 @@ static void reconfigure(struct node *node)
 		}
 		last = c;
 	}
-	if (dst_cnt && !src) {
+	if (dst_cnt > 1 && !src) {
 		if (!rt || rt->dest_only) {
 			node->master = last;
+			/* Reset to original state in next reconfiguration. */
+			node->master->new_state = node->master->state;
+			node->master->state = PS_SLAVE;
+			if (rt)
+				rt->state = PS_SLAVE;
 			pr_info("no source, selecting %s as the default clock",
 				last->device);
 			return;