diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
index 82470c3..396390f 100644
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -443,10 +443,11 @@
 LINKSTATE_GET
 =============
 
-Requests link state information. At the moment, only link up/down flag (as
-provided by ``ETHTOOL_GLINK`` ioctl command) is provided but some future
-extensions are planned (e.g. link down reason). This request does not have any
-attributes.
+Requests link state information. Link up/down flag (as provided by
+``ETHTOOL_GLINK`` ioctl command) is provided. Optionally, extended state might
+be provided as well. In general, extended state describes reasons for why a port
+is down, or why it operates in some non-obvious mode. This request does not have
+any attributes.
 
 Request contents:
 
@@ -461,16 +462,135 @@
   ``ETHTOOL_A_LINKSTATE_LINK``          bool    link state (up/down)
   ``ETHTOOL_A_LINKSTATE_SQI``           u32     Current Signal Quality Index
   ``ETHTOOL_A_LINKSTATE_SQI_MAX``       u32     Max support SQI value
+  ``ETHTOOL_A_LINKSTATE_EXT_STATE``     u8      link extended state
+  ``ETHTOOL_A_LINKSTATE_EXT_SUBSTATE``  u8      link extended substate
   ====================================  ======  ============================
 
 For most NIC drivers, the value of ``ETHTOOL_A_LINKSTATE_LINK`` returns
 carrier flag provided by ``netif_carrier_ok()`` but there are drivers which
 define their own handler.
 
+``ETHTOOL_A_LINKSTATE_EXT_STATE`` and ``ETHTOOL_A_LINKSTATE_EXT_SUBSTATE`` are
+optional values. ethtool core can provide either both
+``ETHTOOL_A_LINKSTATE_EXT_STATE`` and ``ETHTOOL_A_LINKSTATE_EXT_SUBSTATE``,
+or only ``ETHTOOL_A_LINKSTATE_EXT_STATE``, or none of them.
+
 ``LINKSTATE_GET`` allows dump requests (kernel returns reply messages for all
 devices supporting the request).
 
 
+Link extended states:
+
+  ================================================      ============================================
+  ``ETHTOOL_LINK_EXT_STATE_AUTONEG``                    States relating to the autonegotiation or
+                                                        issues therein
+
+  ``ETHTOOL_LINK_EXT_STATE_LINK_TRAINING_FAILURE``      Failure during link training
+
+  ``ETHTOOL_LINK_EXT_STATE_LINK_LOGICAL_MISMATCH``      Logical mismatch in physical coding sublayer
+                                                        or forward error correction sublayer
+
+  ``ETHTOOL_LINK_EXT_STATE_BAD_SIGNAL_INTEGRITY``       Signal integrity issues
+
+  ``ETHTOOL_LINK_EXT_STATE_NO_CABLE``                   No cable connected
+
+  ``ETHTOOL_LINK_EXT_STATE_CABLE_ISSUE``                Failure is related to cable,
+                                                        e.g., unsupported cable
+
+  ``ETHTOOL_LINK_EXT_STATE_EEPROM_ISSUE``               Failure is related to EEPROM, e.g., failure
+                                                        during reading or parsing the data
+
+  ``ETHTOOL_LINK_EXT_STATE_CALIBRATION_FAILURE``        Failure during calibration algorithm
+
+  ``ETHTOOL_LINK_EXT_STATE_POWER_BUDGET_EXCEEDED``      The hardware is not able to provide the
+                                                        power required from cable or module
+
+  ``ETHTOOL_LINK_EXT_STATE_OVERHEAT``                   The module is overheated
+  =================================================     ============================================
+
+Link extended substates:
+
+  Autoneg substates:
+
+  ==============================================================    ================================
+  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_NO_PARTNER_DETECTED``              Peer side is down
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_ACK_NOT_RECEIVED``                 Ack not received from peer side
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_NEXT_PAGE_EXCHANGE_FAILED``        Next page exchange failed
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_NO_PARTNER_DETECTED_FORCE_MODE``   Peer side is down during force
+                                                                    mode or there is no agreement of
+                                                                    speed
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_FEC_MISMATCH_DURING_OVERRIDE``     Forward error correction modes
+                                                                    in both sides are mismatched
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_AN_NO_HCD``                           No Highest Common Denominator
+  ==============================================================    ================================
+
+  Link training substates:
+
+  ==========================================================================    ====================
+  ``ETHTOOL_LINK_EXT_SUBSTATE_LT_KR_FRAME_LOCK_NOT_ACQUIRED``                    Frames were not
+                                                                                 recognized, the
+                                                                                 lock failed
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_LT_KR_LINK_INHIBIT_TIMEOUT``                       The lock did not
+                                                                                 occur before
+                                                                                 timeout
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_LT_KR_LINK_PARTNER_DID_NOT_SET_RECEIVER_READY``    Peer side did not
+                                                                                 send ready signal
+                                                                                 after training
+                                                                                 process
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_LT_REMOTE_FAULT``                                  Remote side is not
+                                                                                 ready yet
+  ==========================================================================    ====================
+
+  Link logical mismatch substates:
+
+  ===============================================================    ===============================
+  ``ETHTOOL_LINK_EXT_SUBSTATE_LLM_PCS_DID_NOT_ACQUIRE_BLOCK_LOCK``   Physical coding sublayer was
+                                                                     not locked in first phase -
+                                                                     block lock
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_LLM_PCS_DID_NOT_ACQUIRE_AM_LOCK``      Physical coding sublayer was
+                                                                     not locked in second phase -
+                                                                     alignment markers lock
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_LLM_PCS_DID_NOT_GET_ALIGN_STATUS``     Physical coding sublayer did
+                                                                     not get align status
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_LLM_FC_FEC_IS_NOT_LOCKED``             FC forward error correction is
+                                                                     not locked
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_LLM_RS_FEC_IS_NOT_LOCKED``             RS forward error correction is
+                                                                     not locked
+  ===============================================================    ===============================
+
+  Bad signal integrity substates:
+
+  =================================================================    =============================
+  ``ETHTOOL_LINK_EXT_SUBSTATE_BSI_LARGE_NUMBER_OF_PHYSICAL_ERRORS``    Large number of physical
+                                                                       errors
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_BSI_UNSUPPORTED_RATE``                   The system attempted to
+                                                                       operate the cable at a rate
+                                                                       that is not formally
+                                                                       supported, which led to
+                                                                       signal integrity issues
+  =================================================================    =============================
+
+  Cable issue substates:
+
+  ==================================================    ============================================
+  ``ETHTOOL_LINK_EXT_SUBSTATE_CI_UNSUPPORTED_CABLE``    Unsupported cable
+
+  ``ETHTOOL_LINK_EXT_SUBSTATE_CI_CABLE_TEST_FAILURE``   Cable test failure
+  ==================================================    ============================================
+
 DEBUG_GET
 =========