Update doc for PERF_VEHICLE_SPEED
Vehicle_speed should be negative if the vehicle is moving in
reverse.
Bug: 127573221
Test: build image
Change-Id: I0cb2baef16a778278a3011ed49e3e36a7da09122
diff --git a/automotive/vehicle/2.0/types.hal b/automotive/vehicle/2.0/types.hal
index ed75e1d..e3fd16d 100644
--- a/automotive/vehicle/2.0/types.hal
+++ b/automotive/vehicle/2.0/types.hal
@@ -354,6 +354,12 @@
/**
* Speed of the vehicle
*
+ * The value must be positive when the vehicle is moving forward and negative when
+ * the vehicle is moving backward. This value is independent of gear value
+ * (CURRENT_GEAR or GEAR_SELECTION), for example, if GEAR_SELECTION is GEAR_NEUTRAL,
+ * PERF_VEHICLE_SPEED is positive when the vehicle is moving forward, negative when moving
+ * backward, and zero when not moving.
+ *
* @change_mode VehiclePropertyChangeMode:CONTINUOUS
* @access VehiclePropertyAccess:READ
* @unit VehicleUnit:METER_PER_SEC