boardd: only look for new usb pandas

selfdrive/boardd/boardd.cc

@@ -472,6 +472,11 @@ void panda_state_thread(PubMaster *pm, std::vector<Panda *> pandas, bool spoofin
   bool is_onroad_last = false;
   std::future<bool> safety_future;
 
+  std::vector<std::string> connected_serials;
+  for (Panda *p : pandas) {
+    connected_serials.push_back(p->hw_serial());
+  }
+
   LOGD("start panda state thread");
 
   // run at 2hz
@@ -499,10 +504,15 @@ void panda_state_thread(PubMaster *pm, std::vector<Panda *> pandas, bool spoofin
         LOGE("Reconnecting, communication to pandas not healthy");
         do_exit = true;
 
-      // TODO: list is slow, takes 16ms
+      } else {
-      } else if (pandas.size() != Panda::list().size()) {
+        // check for new pandas
-        LOGW("Reconnecting to changed amount of pandas!");
+        for (std::string &s : Panda::list(true)) {
-        do_exit = true;
+          if (!std::count(connected_serials.begin(), connected_serials.end(), s)) {
+            LOGW("Reconnecting to new panda: %s", s.c_str());
+            do_exit = true;
+            break;
+          }
+        }
       }
 
       if (do_exit) {

selfdrive/boardd/panda.cc

@@ -44,13 +44,15 @@ std::string Panda::hw_serial() {
   return handle->hw_serial;
 }
 
-std::vector<std::string> Panda::list() {
+std::vector<std::string> Panda::list(bool usb_only) {
   std::vector<std::string> serials = PandaUsbHandle::list();
 
 #ifndef __APPLE__
-  for (auto s : PandaSpiHandle::list()) {
+  if (!usb_only) {
-    if (std::find(serials.begin(), serials.end(), s) == serials.end()) {
+    for (auto s : PandaSpiHandle::list()) {
-      serials.push_back(s);
+      if (std::find(serials.begin(), serials.end(), s) == serials.end()) {
+        serials.push_back(s);
+      }
     }
   }
 #endif

selfdrive/boardd/panda.h

@@ -57,7 +57,7 @@ public:
   std::string hw_serial();
 
   // Static functions
-  static std::vector<std::string> list();
+  static std::vector<std::string> list(bool usb_only=false);
 
   // Panda functionality
   cereal::PandaState::PandaType get_hw_type();