[CMIS] 'get_transceiver_info' should return 'None' when CMIS cable EE…

…PROM is not ready (#305)

* get_transceiver_info should return None when cmis cable eeprom is not ready

Signed-off-by: Kebo Liu <kebol@nvidia.com>

* Add more comments to describe the change

Signed-off-by: Kebo Liu <kebol@nvidia.com>

Signed-off-by: Kebo Liu <kebol@nvidia.com>

sonic_platform_base/sonic_xcvr/api/public/cmis.py

@@ -164,7 +164,16 @@ def get_transceiver_info(self):
         xcvr_info['active_firmware'] = self.get_module_active_firmware()
         xcvr_info['inactive_firmware'] = self.get_module_inactive_firmware()
         xcvr_info['specification_compliance'] = self.get_module_media_type()
-        return xcvr_info
+
+        # In normal case will get a valid value for each of the fields. If get a 'None' value
+        # means there was a failure while reading the EEPROM, either because the EEPROM was
+        # not ready yet or experincing some other issues. It shouldn't return a dict with a
+        # wrong field value, instead should return a 'None' to indicate to XCVRD that retry is
+        # needed.
+        if None in xcvr_info.values():
+            return None
+        else:
+            return xcvr_info
 
     def get_transceiver_bulk_status(self):
         rx_los = self.get_rx_los()

tests/sonic_xcvr/test_cmis.py

@@ -1157,6 +1157,10 @@ def test_get_transceiver_info(self, mock_response, expected):
         self.api.is_flat_memory.return_value = False
         result = self.api.get_transceiver_info()
         assert result == expected
+        # Test negative path
+        self.api.get_cmis_rev.return_value = None
+        result = self.api.get_transceiver_info()
+        assert result == None
 
 
     @pytest.mark.parametrize("mock_response, expected",[