[Mellanox] Re-initialize SFP object when detecting a new SFP insertion (

#5695)

When detecting a new SFP insertion, read its SFP type and DOM capability from EEPROM again.

SFP object will be initialized to a certain type even if no SFP present. A case could be:

1. A SFP object is initialized to QSFP type by default when there is no SFP present
2. User insert a SFP with an adapter to this QSFP port
3. The SFP object fail to read EEPROM because it still treats itself as QSFP.

This PR fixes this issue.

platform/mellanox/mlnx-platform-api/sonic_platform/chassis.py

@@ -471,10 +471,29 @@ def get_change_event(self, timeout=0):
             status = self.sfp_event.check_sfp_status(port_dict, timeout)
 
         if status:
+            self.reinit_sfps(port_dict)
             return True, {'sfp':port_dict}
         else:
             return True, {'sfp':{}}
 
+    def reinit_sfps(self, port_dict):
+        """
+        Re-initialize SFP if there is any newly inserted SFPs
+        :param port_dict: SFP event data
+        :return:
+        """
+        # SFP not initialize yet, do nothing
+        if not self.sfp_module_initialized:
+            return
+
+        from . import sfp
+        for index, status in port_dict.items():
+            if status == sfp.SFP_STATUS_INSERTED:
+                try:
+                    self.get_sfp(index).reinit()
+                except Exception as e:
+                    logger.log_error("Fail to re-initialize SFP {} - {}".format(index, repr(e)))
+
     def get_thermal_manager(self):
         from .thermal_manager import ThermalManager
         return ThermalManager

platform/mellanox/mlnx-platform-api/sonic_platform/sfp.py

@@ -279,6 +279,9 @@
 NVE_MASK = PORT_TYPE_MASK & (PORT_TYPE_NVE << PORT_TYPE_OFFSET)
 CPU_MASK = PORT_TYPE_MASK & (PORT_TYPE_CPU << PORT_TYPE_OFFSET)
 
+# parameters for SFP presence
+SFP_STATUS_INSERTED = '1'
+
 # Global logger class instance
 logger = Logger()
 
@@ -316,6 +319,13 @@ def __init__(self, sfp_index, sfp_type, sdk_handle):
         self.sdk_handle = sdk_handle
         self.sdk_index = sfp_index
 
+    def reinit(self):
+        """
+        Re-initialize this SFP object when a new SFP inserted
+        :return: 
+        """
+        self._detect_sfp_type(self.sfp_type)
+        self._dom_capability_detect()
 
     def get_presence(self):
         """