Hyundai longitudinal (CAN): don't send FCA11 on non-FCA cars (#28479)

* Hyundai longitudinal (CAN): don't send FCA messages to non-FCA cars

* Update comments

* outside

* change to FCA11 only

* move down

* add todos

* Apply suggestions from code review

* add todo

---------

Co-authored-by: Shane Smiskol <shane@smiskol.com>

selfdrive/car/hyundai/carcontroller.py

@@ -171,8 +171,10 @@ class CarController:
       if self.frame % 2 == 0 and self.CP.openpilotLongitudinalControl:
         # TODO: unclear if this is needed
         jerk = 3.0 if actuators.longControlState == LongCtrlState.pid else 1.0
+        use_fca = self.CP.flags & HyundaiFlags.USE_FCA.value
         can_sends.extend(hyundaican.create_acc_commands(self.packer, CC.enabled, accel, jerk, int(self.frame / 2),
-                                                        hud_control.leadVisible, set_speed_in_units, stopping, CC.cruiseControl.override))
+                                                        hud_control.leadVisible, set_speed_in_units, stopping,
+                                                        CC.cruiseControl.override, use_fca))
 
       # 20 Hz LFA MFA message
       if self.frame % 5 == 0 and self.CP.flags & HyundaiFlags.SEND_LFA.value:

selfdrive/car/hyundai/hyundaican.py

@@ -125,7 +125,7 @@ def create_lfahda_mfc(packer, enabled, hda_set_speed=0):
   }
   return packer.make_can_msg("LFAHDA_MFC", 0, values)
 
-def create_acc_commands(packer, enabled, accel, upper_jerk, idx, lead_visible, set_speed, stopping, long_override):
+def create_acc_commands(packer, enabled, accel, upper_jerk, idx, lead_visible, set_speed, stopping, long_override, use_fca):
   commands = []
 
   scc11_values = {
@@ -163,6 +163,8 @@ def create_acc_commands(packer, enabled, accel, upper_jerk, idx, lead_visible, s
   }
   commands.append(packer.make_can_msg("SCC14", 0, scc14_values))
 
+  # Only send FCA11 on cars where it exists on the bus
+  if use_fca:
     # note that some vehicles most likely have an alternate checksum/counter definition
     # https://github.com/commaai/opendbc/commit/9ddcdb22c4929baf310295e832668e6e7fcfa602
     fca11_values = {
@@ -187,6 +189,7 @@ def create_acc_opt(packer):
   }
   commands.append(packer.make_can_msg("SCC13", 0, scc13_values))
 
+  # TODO: this needs to be detected and conditionally sent on unsupported long cars
   fca12_values = {
     "FCA_DrvSetState": 2,
     "FCA_USM": 1, # AEB disabled