ptp: clarify the clock_name sysfs attribute

There has been some confusion among PHC driver authors about the
intended purpose of the clock_name attribute. This patch expands the
documation in order to clarify how the clock_name field should be
understood.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/Documentation/ABI/testing/sysfs-ptp b/Documentation/ABI/testing/sysfs-ptp
index d40d2b550502..05aeedf17794 100644
--- a/Documentation/ABI/testing/sysfs-ptp
+++ b/Documentation/ABI/testing/sysfs-ptp
@@ -19,7 +19,11 @@ Date:		September 2010
 Contact:        Richard Cochran <richardcochran@gmail.com>
 Description:
                 This file contains the name of the PTP hardware clock
-                as a human readable string.
+                as a human readable string. The purpose of this
+                attribute is to provide the user with a "friendly
+                name" and to help distinguish PHY based devices from
+                MAC based ones. The string does not necessarily have
+                to be any kind of unique id.
 
 What:           /sys/class/ptp/ptpN/max_adjustment
 Date:           September 2010