VIN: lower retries (#31471)

* lower retries

* comment

selfdrive/car/car_helpers.py

@@ -141,9 +141,10 @@ def fingerprint(logcan, sendcan, num_pandas):
       cached = True
     else:
       cloudlog.warning("Getting VIN & FW versions")
-      # enable OBD multiplexing for Vin query, also allows time for sendcan subscriber to connect
+      # enable OBD multiplexing for VIN query
+      # NOTE: this takes ~0.1s and is relied on to allow sendcan subscriber to connect in time
       set_obd_multiplexing(params, True)
-      # Vin query only reliably works through OBDII
+      # VIN query only reliably works through OBDII
       vin_rx_addr, vin_rx_bus, vin = get_vin(logcan, sendcan, (0, 1))
       ecu_rx_addrs = get_present_ecus(logcan, sendcan, num_pandas=num_pandas)
       car_fw = get_fw_versions_ordered(logcan, sendcan, ecu_rx_addrs, num_pandas=num_pandas)

selfdrive/car/tests/test_fw_fingerprint.py

@@ -225,7 +225,7 @@ class TestFwFingerprintTiming(unittest.TestCase):
 
   def test_startup_timing(self):
     # Tests worse-case VIN query time and typical present ECU query time
-    vin_ref_times = {'worst': 1.5, 'best': 0.5}  # best assumes we go through all queries to get a match
+    vin_ref_times = {'worst': 1.0, 'best': 0.5}  # best assumes we go through all queries to get a match
     present_ecu_ref_time = 0.75
 
     def fake_get_ecu_addrs(*_, timeout):

selfdrive/car/vin.py

@@ -15,7 +15,7 @@ def is_valid_vin(vin: str):
   return re.fullmatch(VIN_RE, vin) is not None
 
 
-def get_vin(logcan, sendcan, buses, timeout=0.1, retry=3, debug=False):
+def get_vin(logcan, sendcan, buses, timeout=0.1, retry=2, debug=False):
   for i in range(retry):
     for bus in buses:
       for request, response, valid_buses, vin_addrs, functional_addrs, rx_offset in (