Hyundai CAN-FD: Add CAN fingerprint fallback checks for HDA2 detection

opendbc/car/hyundai/hyundaicanfd.py

@@ -4,12 +4,11 @@
 
 
 class CanBus(CanBusBase):
-  def __init__(self, CP, hda2=None, fingerprint=None) -> None:
+  def __init__(self, CP, fingerprint=None, hda2=None) -> None:
     super().__init__(CP, fingerprint)
 
     if hda2 is None:
-      assert CP is not None
-      hda2 = CP.flags & HyundaiFlags.CANFD_HDA2.value
+      hda2 = CP.flags & HyundaiFlags.CANFD_HDA2.value if CP is not None else False
 
     # On the CAN-FD platforms, the LKAS camera is on both A-CAN and E-CAN. HDA2 cars
     # have a different harness than the HDA1 and non-HDA variants in order to split

opendbc/car/hyundai/interface.py

@@ -18,8 +18,11 @@ class CarInterface(CarInterfaceBase):
   def _get_params(ret: structs.CarParams, candidate, fingerprint, car_fw, experimental_long, docs) -> structs.CarParams:
     ret.carName = "hyundai"
 
-    hda2 = Ecu.adas in [fw.ecu for fw in car_fw]
-    CAN = CanBus(None, hda2, fingerprint)
+    # Check the CAM bus fingerprint for known HDA2 steering messages (0x50 or 0x110) to determine if it is an HDA2 car.
+    cam_can = CanBus(None, fingerprint).CAM
+    hda2 = 0x50 in fingerprint[cam_can] or 0x110 in fingerprint[cam_can]
+
+    CAN = CanBus(None, fingerprint, hda2)
 
     if candidate in CANFD_CAR:
       # Shared configuration for CAN-FD cars

opendbc/car/hyundai/tests/test_hyundai.py

@@ -6,6 +6,7 @@
 from opendbc.car.structs import CarParams
 from opendbc.car.fw_versions import build_fw_dict
 from opendbc.car.hyundai.interface import CarInterface
+from opendbc.car.hyundai.hyundaicanfd import CanBus
 from opendbc.car.hyundai.radar_interface import RADAR_START_ADDR
 from opendbc.car.hyundai.values import CAMERA_SCC_CAR, CANFD_CAR, CAN_GEARS, CAR, CHECKSUM, DATE_FW_ECUS, \
                                          HYBRID_CAR, EV_CAR, FW_QUERY_CONFIG, LEGACY_SAFETY_MODE_CAR, CANFD_FUZZY_WHITELIST, \
@@ -44,17 +45,20 @@
 class TestHyundaiFingerprint:
   def test_feature_detection(self):
     # HDA2
-    for has_adas in (True, False):
-      car_fw = [CarParams.CarFw(ecu=Ecu.adas if has_adas else Ecu.fwdCamera)]
-      CP = CarInterface.get_params(CAR.KIA_EV6, gen_empty_fingerprint(), car_fw, False, False)
-      assert bool(CP.flags & HyundaiFlags.CANFD_HDA2) == has_adas
+    for hda2 in (True, False):
+      fingerprint = gen_empty_fingerprint()
+      if hda2:
+        cam_can = CanBus(None, fingerprint).CAM
+        fingerprint[cam_can] = [0x50, 0x110]  # HDA2 steering messages
+      CP = CarInterface.get_params(CAR.KIA_EV6, fingerprint, [], False, False)
+      assert bool(CP.flags & HyundaiFlags.CANFD_HDA2) == hda2
 
     # radar available
     for radar in (True, False):
       fingerprint = gen_empty_fingerprint()
       if radar:
         fingerprint[1][RADAR_START_ADDR] = 8
-      CP = CarInterface.get_params(CAR.HYUNDAI_SONATA, fingerprint, car_fw, False, False)
+      CP = CarInterface.get_params(CAR.HYUNDAI_SONATA, fingerprint, [], False, False)
       assert CP.radarUnavailable != radar
 
   def test_can_features(self):