diff --git a/phc2sys.8 b/phc2sys.8
index 010fa18..8e03e81 100644
--- a/phc2sys.8
+++ b/phc2sys.8
@@ -40,9 +40,9 @@ program.
 
 Two synchronization modes are supported, one uses a pulse per second (PPS)
 signal provided by the source clock and the other mode reads time from the
-source clock directly. The PPS mode is usually preferred, because reading the
-PHC is slow and introduces an unknown error in the readings, but not all PHCs
-provide the PPS signal.
+source clock directly. Some clocks can be used in both modes, the mode which
+will synchronize the slave clock with better accuracy depends on hardware and
+driver implementation.
 
 .SH OPTIONS
 .TP
@@ -58,7 +58,7 @@ option should be used too. This option can be used only with the system clock as
 the slave clock.
 .TP
 .BI \-s " device"
-Specify the master clock by device (e.g. dev/ptp0) or interface (e.g. eth0) or
+Specify the master clock by device (e.g. /dev/ptp0) or interface (e.g. eth0) or
 by name (e.g. CLOCK_REALTIME for the system clock). When this option is used
 together with the
 .B \-d
diff --git a/ptp4l.8 b/ptp4l.8
index a722d77..43a8697 100644
--- a/ptp4l.8
+++ b/ptp4l.8
@@ -32,10 +32,13 @@ a peer delay request is received.
 .TP
 .B \-E
 Select the delay request-response (E2E) mechanism. This is the default
-mechanism.
+mechanism. All clocks on single PTP communication path must use the same
+mechanism. A warning will be printed when a peer delay request is received on
+port using the E2E mechanism.
 .TP
 .B \-P
-Select the peer delay (P2P) mechanism.
+Select the peer delay (P2P) mechanism. A warning will be printed when a delay
+request is received on port using the P2P mechanism.
 .TP
 .B \-2
 Select the IEEE 802.3 network transport.