ui: fix brightness when there's no camera (#32413)

old-commit-hash: 79c8fb0236

selfdrive/ui/ui.cc

@@ -205,6 +205,8 @@ static void update_state(UIState *s) {
     auto cam_state = sm["wideRoadCameraState"].getWideRoadCameraState();
     float scale = (cam_state.getSensor() == cereal::FrameData::ImageSensor::AR0231) ? 6.0f : 1.0f;
     scene.light_sensor = std::max(100.0f - scale * cam_state.getExposureValPercent(), 0.0f);
+  } else if (!sm.allAliveAndValid({"wideRoadCameraState"})) {
+    scene.light_sensor = -1;
   }
   scene.started = sm["deviceState"].getDeviceState().getStarted() && scene.ignition;
 
@@ -320,7 +322,7 @@ void Device::resetInteractiveTimeout(int timeout) {
 
 void Device::updateBrightness(const UIState &s) {
   float clipped_brightness = offroad_brightness;
-  if (s.scene.started) {
+  if (s.scene.started && s.scene.light_sensor > 0) {
     clipped_brightness = s.scene.light_sensor;
 
     // CIE 1931 - https://www.photonstophotos.net/GeneralTopics/Exposure/Psychometric_Lightness_and_Gamma.htm

selfdrive/ui/ui.h

@@ -97,7 +97,7 @@ typedef struct UIScene {
 
   cereal::LongitudinalPersonality personality;
 
-  float light_sensor;
+  float light_sensor = -1;
   bool started, ignition, is_metric, map_on_left, longitudinal_control;
   bool world_objects_visible = false;
   uint64_t started_frame;