From 2962fc62862c7c0d888d83a7b76e05bbc6416eb1 Mon Sep 17 00:00:00 2001
From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Mon, 21 May 2018 16:49:26 +0200
Subject: [PATCH] ntp: check PHC index before opening device

Apparently, it is possible for an interface to report all necessary
flags for HW timestamping without having a PHC. Check the PHC index to
avoid an error message in the system log saying that /dev/ptp-1 cannot
be opened.
---
 ntp_io_linux.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/ntp_io_linux.c b/ntp_io_linux.c
index 6f794c7..da39c95 100644
--- a/ntp_io_linux.c
+++ b/ntp_io_linux.c
@@ -171,6 +171,12 @@ add_interface(CNF_HwTsInterface *conf_iface)
     return 0;
   }
 
+  if (ts_info.phc_index < 0) {
+    DEBUG_LOG("PHC missing on %s", req.ifr_name);
+    close(sock_fd);
+    return 0;
+  }
+
   ts_config.flags = 0;
   ts_config.tx_type = HWTSTAMP_TX_ON;