GM: fix fault while moving backwards (#26333)

* log signed speed

* bump to master

* need this

* fix

* fix...

* see if this works

* just fault fix (no logging or standstill. tho revisit standstill)

* move

* Revert "move"

This reverts commit c564e74666.

opendbc

@@ -1 +1 @@
-Subproject commit b3dc569994fd10e4de04afd650980c51ddfce5e1
+Subproject commit 296f190000a2e71408e207ba21a2257cc853ec15

selfdrive/car/gm/carstate.py

@@ -28,6 +28,7 @@ class CarState(CarStateBase):
     self.cruise_buttons = pt_cp.vl["ASCMSteeringButton"]["ACCButtons"]
     self.buttons_counter = pt_cp.vl["ASCMSteeringButton"]["RollingCounter"]
     self.pscm_status = copy.copy(pt_cp.vl["PSCMStatus"])
+    self.moving_backward = pt_cp.vl["EBCMWheelSpdRear"]["MovingBackward"] != 0
 
     # Variables used for avoiding LKAS faults
     self.loopback_lka_steering_cmd_updated = len(loopback_cp.vl_all["ASCMLKASteeringCmd"]["RollingCounter"]) > 0
@@ -139,6 +140,7 @@ class CarState(CarStateBase):
       ("FRWheelSpd", "EBCMWheelSpdFront"),
       ("RLWheelSpd", "EBCMWheelSpdRear"),
       ("RRWheelSpd", "EBCMWheelSpdRear"),
+      ("MovingBackward", "EBCMWheelSpdRear"),
       ("PRNDL2", "ECMPRDNL2"),
       ("ManualMode", "ECMPRDNL2"),
       ("LKADriverAppldTrq", "PSCMStatus"),

selfdrive/car/gm/interface.py

@@ -225,7 +225,8 @@ class CarInterface(CarInterfaceBase):
 
     # Enabling at a standstill with brake is allowed
     # TODO: verify 17 Volt can enable for the first time at a stop and allow for all GMs
-    if ret.vEgo < self.CP.minEnableSpeed and not (ret.standstill and ret.brake >= 20 and
+    below_min_enable_speed = ret.vEgo < self.CP.minEnableSpeed or self.CS.moving_backward
+    if below_min_enable_speed and not (ret.standstill and ret.brake >= 20 and
                                        self.CP.networkLocation == NetworkLocation.fwdCamera):
       events.add(EventName.belowEngageSpeed)
     if ret.cruiseState.standstill: