this was the cleanest I could think of, but still working on it. not very easy to understand

selfdrive/car/fw_versions.py

@@ -54,11 +54,13 @@ def get_brand_addrs() -> Dict[str, Set[Tuple[int, Optional[int]]]]:
   return dict(brand_addrs)
 
 
-def match_fw_to_car_fuzzy(fw_versions_dict, config, log=True, exclude=None):
+def match_fw_to_car_fuzzy(fw_versions_dict, config=None, log=True, exclude=None):
   """Do a fuzzy FW match. This function will return a match, and the number of firmware version
   that were matched uniquely to that specific car. If multiple ECUs uniquely match to different cars
   the match is rejected."""
 
+  use_config = config is not None and config.fuzzy_get_platform_codes is not None
+
   # Build lookup table from (addr, sub_addr, fw) to list of candidate cars
   all_fw_versions = defaultdict(list)
   # Platform codes are brand-specific unique identifiers for each platform, less specific than a FW version
@@ -77,7 +79,7 @@ def match_fw_to_car_fuzzy(fw_versions_dict, config, log=True, exclude=None):
           all_fw_versions[(addr[1], addr[2], f)].append(candidate)
 
       # Add platform codes to lookup dict if config specifies a function
-      if addr[0] in config.fuzzy_ecus and config.fuzzy_get_platform_codes is not None:
+      if use_config and addr[0] in config.fuzzy_ecus:
         for platform_code in config.fuzzy_get_platform_codes(fws):
           all_platform_codes[(addr[1], addr[2], platform_code)].append(candidate)
 
@@ -90,11 +92,11 @@ def match_fw_to_car_fuzzy(fw_versions_dict, config, log=True, exclude=None):
   for addr, versions in fw_versions_dict.items():
     ecu_key = (addr[0], addr[1])
     for version in versions:
-      # All cars that have this FW response on the specified address
+      # Fall back to matching with full FW versions if brand does not implement platform codes
+      candidates = set()
+      if not use_config:
         candidates = all_fw_versions[(*ecu_key, version)]
-
-      # If no exact FW matches, try brand-specific fuzzy fingerprinting
-      if len(candidates) != 1 and config.fuzzy_get_platform_codes is not None:
+      else:
         # Returns one or none, all cars that have this platform code
         for platform_code in config.fuzzy_get_platform_codes([version]):
           candidates = all_platform_codes[(*ecu_key, platform_code)]
@@ -109,7 +111,8 @@ def match_fw_to_car_fuzzy(fw_versions_dict, config, log=True, exclude=None):
 
   # Note that it is possible to match to a candidate without all its ECUs being present
   # if there are enough matches. FIXME: parameterize this or require all ECUs to exist like exact matching
-  if len(matched_ecus) >= config.fuzzy_min_match_count:
+  fuzzy_min_match_count = config.fuzzy_min_match_count if use_config else 2
+  if len(matched_ecus) >= fuzzy_min_match_count:
     if log:
       cloudlog.error(f"Fingerprinted {candidate} using fuzzy match. {len(matched_ecus)} matching ECUs")
     return {candidate}
@@ -158,14 +161,17 @@ def match_fw_to_car(fw_versions, allow_exact=True, allow_fuzzy=True, log=True):
   if allow_exact:
     exact_matches = [(True, match_fw_to_car_exact)]
   if allow_fuzzy:
-    exact_matches.append((False, match_fw_to_car_fuzzy))
+    # Try first with standard fuzzy fingerprinting, then with config
+    exact_matches.extend([(False, False, match_fw_to_car_fuzzy),
+                          (False, True, match_fw_to_car_fuzzy)])
 
-  for exact_match, match_func in exact_matches:
+  for exact_match, use_config, match_func in exact_matches:
     # For each brand, attempt to fingerprint using all FW returned from its queries
     matches = set()
     for brand in VERSIONS.keys():
       fw_versions_dict = build_fw_dict(fw_versions, filter_brand=brand)
-      matches |= match_func(fw_versions_dict, FW_QUERY_CONFIGS[brand], log=log)
+      config = FW_QUERY_CONFIGS[brand] if use_config else None
+      matches |= match_func(fw_versions_dict, config, log=log)
 
     if len(matches):
       return exact_match, matches