net: ethtool: Add impedance mismatch result code to cable test

Some PHYs can recognize during a cable test if the impedance in the cable
is okay. They can detect reflections caused by impedance discontinuity
between a regular 100 Ohm cable and an abnormal part with a higher or
lower impedance.

This commit introduces a new result code:
ETHTOOL_A_CABLE_RESULT_CODE_IMPEDANCE_MISMATCH,
which represents the results of a cable test indicating issues with
impedance integrity.

Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20240402201123.2961909-2-paweldembicki@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 3f89074..accbb1a 100644 (file)
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -515,6 +515,10 @@ enum {
        ETHTOOL_A_CABLE_RESULT_CODE_OPEN,
        ETHTOOL_A_CABLE_RESULT_CODE_SAME_SHORT,
        ETHTOOL_A_CABLE_RESULT_CODE_CROSS_SHORT,
+       /* detected reflection caused by the impedance discontinuity between
+        * a regular 100 Ohm cable and a part with the abnormal impedance value
+        */
+       ETHTOOL_A_CABLE_RESULT_CODE_IMPEDANCE_MISMATCH,
 };
 
 enum {