handle usb error in reading panda state (#23686)

old-commit-hash: f2eb84eef0

selfdrive/boardd/boardd.cc

@@ -294,7 +294,7 @@ void send_empty_panda_state(PubMaster *pm) {
   pm->send("pandaStates", msg);
 }
 
-bool send_panda_states(PubMaster *pm, const std::vector<Panda *> &pandas, bool spoofing_started) {
+std::optional<bool> send_panda_states(PubMaster *pm, const std::vector<Panda *> &pandas, bool spoofing_started) {
   bool ignition_local = false;
 
   // build msg
@@ -304,7 +304,12 @@ bool send_panda_states(PubMaster *pm, const std::vector<Panda *> &pandas, bool s
 
   std::vector<health_t> pandaStates;
   for (const auto& panda : pandas){
-    health_t health = panda->get_state();
+    auto health_opt = panda->get_state();
+    if (!health_opt) {
+      return std::nullopt;
+    }
+
+    health_t health = *health_opt;
 
     if (spoofing_started) {
       health.ignition_line_pkt = 1;
@@ -379,7 +384,12 @@ bool send_panda_states(PubMaster *pm, const std::vector<Panda *> &pandas, bool s
 }
 
 void send_peripheral_state(PubMaster *pm, Panda *panda) {
-  health_t pandaState = panda->get_state();
+  auto pandaState_opt = panda->get_state();
+  if (!pandaState_opt) {
+    return;
+  }
+
+  health_t pandaState = *pandaState_opt;
 
   // build msg
   MessageBuilder msg;
@@ -427,7 +437,13 @@ void panda_state_thread(PubMaster *pm, std::vector<Panda *> pandas, bool spoofin
 
     // send out peripheralState
     send_peripheral_state(pm, peripheral_panda);
-    ignition = send_panda_states(pm, pandas, spoofing_started);
+    auto ignition_opt = send_panda_states(pm, pandas, spoofing_started);
+
+    if (!ignition_opt) {
+      continue;
+    }
+
+    ignition = *ignition_opt;
 
     // TODO: make this check fast, currently takes 16ms
     // check if we have new pandas and are offroad

selfdrive/boardd/panda.cc

@@ -311,10 +311,10 @@ void Panda::set_ir_pwr(uint16_t ir_pwr) {
   usb_write(0xb0, ir_pwr, 0);
 }
 
-health_t Panda::get_state() {
+std::optional<health_t> Panda::get_state() {
   health_t health {0};
-  usb_read(0xd2, 0, 0, (unsigned char*)&health, sizeof(health));
-  return health;
+  int err = usb_read(0xd2, 0, 0, (unsigned char*)&health, sizeof(health));
+  return err >= 0 ? std::make_optional(health) : std::nullopt;
 }
 
 void Panda::set_loopback(bool loopback) {

selfdrive/boardd/panda.h

@@ -80,7 +80,7 @@ class Panda {
   void set_fan_speed(uint16_t fan_speed);
   uint16_t get_fan_speed();
   void set_ir_pwr(uint16_t ir_pwr);
-  health_t get_state();
+  std::optional<health_t> get_state();
   void set_loopback(bool loopback);
   std::optional<std::vector<uint8_t>> get_firmware_version();
   std::optional<std::string> get_serial();