[wifi] Avoid redundant SDK calls in WiFi loop on ESP8266 (#15303)

esphome/components/wifi/wifi_component.cpp

@@ -784,7 +784,8 @@ void WiFiComponent::loop() {
       }
 
       case WIFI_COMPONENT_STATE_STA_CONNECTED: {
-        if (!this->is_connected_()) {
+        // Use cached connected_ set unconditionally at the top of loop()
+        if (!this->connected_) {
           ESP_LOGW(TAG, "Connection lost; reconnecting");
           this->state_ = WIFI_COMPONENT_STATE_STA_CONNECTING;
           this->retry_connect();
@@ -2129,11 +2130,6 @@ void WiFiComponent::retry_connect() {
 }
 
 void WiFiComponent::set_reboot_timeout(uint32_t reboot_timeout) { this->reboot_timeout_ = reboot_timeout; }
-bool WiFiComponent::is_connected_() const {
-  return this->state_ == WIFI_COMPONENT_STATE_STA_CONNECTED &&
-         this->wifi_sta_connect_status_() == WiFiSTAConnectStatus::CONNECTED && !this->error_from_callback_;
-}
-void WiFiComponent::update_connected_state_() { this->connected_ = this->is_connected_(); }
 void WiFiComponent::set_power_save_mode(WiFiPowerSaveMode power_save) {
   this->power_save_ = power_save;
 #if defined(USE_ESP32) && defined(USE_WIFI_RUNTIME_POWER_SAVE)

esphome/components/wifi/wifi_component.h

@@ -670,8 +670,11 @@ class WiFiComponent final : public Component {
   bool wifi_sta_connect_(const WiFiAP &ap);
   void wifi_pre_setup_();
   WiFiSTAConnectStatus wifi_sta_connect_status_() const;
-  bool is_connected_() const;
+  bool is_connected_() const {
-  void update_connected_state_();
+    return this->state_ == WIFI_COMPONENT_STATE_STA_CONNECTED &&
+           this->wifi_sta_connect_status_() == WiFiSTAConnectStatus::CONNECTED && !this->error_from_callback_;
+  }
+  void update_connected_state_() { this->connected_ = this->is_connected_(); }
   bool wifi_scan_start_(bool passive);
 
 #ifdef USE_WIFI_AP
@@ -811,6 +814,12 @@ class WiFiComponent final : public Component {
   uint8_t num_ipv6_addresses_{0};
 #endif /* USE_NETWORK_IPV6 */
   bool error_from_callback_{false};
+#ifdef USE_ESP8266
+  // ESP8266WiFiSTAState enum, defined in wifi_component_esp8266.cpp.
+  // Written from SDK system context (wifi_event_callback) — uint8_t writes
+  // are atomic on Xtensa LX106 so no synchronization is needed.
+  uint8_t sta_state_{0};
+#endif
   RetryHiddenMode retry_hidden_mode_{RetryHiddenMode::BLIND_RETRY};
   RoamingState roaming_state_{RoamingState::IDLE};
   bssid_t roaming_target_bssid_{};  // BSSID of the AP we're trying to roam to

esphome/components/wifi/wifi_component_esp8266.cpp

@@ -44,11 +44,14 @@ namespace esphome::wifi {
 
 static const char *const TAG = "wifi_esp8266";
 
-static bool s_sta_connected = false;          // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+enum class ESP8266WiFiSTAState : uint8_t {
-static bool s_sta_got_ip = false;             // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+  IDLE,             // Not connecting
-static bool s_sta_connect_not_found = false;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+  CONNECTING,       // Connection in progress
-static bool s_sta_connect_error = false;      // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+  ASSOCIATED,       // Associated to AP, waiting for IP
-static bool s_sta_connecting = false;         // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+  CONNECTED,        // Successfully connected with IP
+  ERROR_NOT_FOUND,  // AP not found (probe failed)
+  ERROR_FAILED,     // Connection failed (auth, timeout, etc.)
+};
 
 bool WiFiComponent::wifi_mode_(optional<bool> sta, optional<bool> ap) {
   uint8_t current_mode = wifi_get_opmode();
@@ -359,11 +362,7 @@ bool WiFiComponent::wifi_sta_connect_(const WiFiAP &ap) {
 
   // Reset flags, do this _before_ wifi_station_connect as the callback method
   // may be called from wifi_station_connect
-  s_sta_connecting = true;
+  this->sta_state_ = static_cast<uint8_t>(ESP8266WiFiSTAState::CONNECTING);
-  s_sta_connected = false;
-  s_sta_got_ip = false;
-  s_sta_connect_error = false;
-  s_sta_connect_not_found = false;
 
   ETS_UART_INTR_DISABLE();
   ret = wifi_station_connect();
@@ -493,7 +492,7 @@ void WiFiComponent::wifi_event_callback(System_Event_t *event) {
       ESP_LOGV(TAG, "Connected ssid='%.*s' bssid=%s channel=%u", it.ssid_len, (const char *) it.ssid, bssid_buf,
                it.channel);
 #endif
-      s_sta_connected = true;
+      global_wifi_component->sta_state_ = static_cast<uint8_t>(ESP8266WiFiSTAState::ASSOCIATED);
 #ifdef USE_WIFI_CONNECT_STATE_LISTENERS
       // Defer listener notification until state machine reaches STA_CONNECTED
       // This ensures wifi.connected condition returns true in listener automations
@@ -506,16 +505,14 @@ void WiFiComponent::wifi_event_callback(System_Event_t *event) {
       if (it.reason == REASON_NO_AP_FOUND) {
         ESP_LOGW(TAG, "Disconnected ssid='%.*s' reason='Probe Request Unsuccessful'", it.ssid_len,
                  (const char *) it.ssid);
-        s_sta_connect_not_found = true;
+        global_wifi_component->sta_state_ = static_cast<uint8_t>(ESP8266WiFiSTAState::ERROR_NOT_FOUND);
       } else {
         char bssid_s[18];
         format_mac_addr_upper(it.bssid, bssid_s);
         ESP_LOGW(TAG, "Disconnected ssid='%.*s' bssid=" LOG_SECRET("%s") " reason='%s'", it.ssid_len,
                  (const char *) it.ssid, bssid_s, LOG_STR_ARG(get_disconnect_reason_str(it.reason)));
-        s_sta_connect_error = true;
+        global_wifi_component->sta_state_ = static_cast<uint8_t>(ESP8266WiFiSTAState::ERROR_FAILED);
       }
-      s_sta_connected = false;
-      s_sta_connecting = false;
       global_wifi_component->error_from_callback_ = true;
 #ifdef USE_WIFI_CONNECT_STATE_LISTENERS
       global_wifi_component->pending_.disconnect = true;
@@ -541,7 +538,7 @@ void WiFiComponent::wifi_event_callback(System_Event_t *event) {
           mask_buf[network::IP_ADDRESS_BUFFER_SIZE];
       ESP_LOGV(TAG, "static_ip=%s gateway=%s netmask=%s", network::IPAddress(&it.ip).str_to(ip_buf),
                network::IPAddress(&it.gw).str_to(gw_buf), network::IPAddress(&it.mask).str_to(mask_buf));
-      s_sta_got_ip = true;
+      global_wifi_component->sta_state_ = static_cast<uint8_t>(ESP8266WiFiSTAState::CONNECTED);
 #ifdef USE_WIFI_IP_STATE_LISTENERS
       // Defer listener callbacks to main loop - system context has limited stack
       global_wifi_component->pending_.got_ip = true;
@@ -636,17 +633,22 @@ void WiFiComponent::wifi_pre_setup_() {
 }
 
 WiFiSTAConnectStatus WiFiComponent::wifi_sta_connect_status_() const {
-  station_status_t status = wifi_station_get_connect_status();
+  // Use cached state from wifi_event_callback() instead of calling
-  if (status == STATION_GOT_IP)
+  // wifi_station_get_connect_status() which queries the SDK every time.
+  // Use if statements with early returns instead of switch to avoid GCC
+  // generating a CSWTCH lookup table in .rodata (flash) on ESP8266.
+  auto state = static_cast<ESP8266WiFiSTAState>(this->sta_state_);
+  if (state == ESP8266WiFiSTAState::CONNECTED)
     return WiFiSTAConnectStatus::CONNECTED;
-  if (status == STATION_NO_AP_FOUND)
+  if (state == ESP8266WiFiSTAState::ERROR_NOT_FOUND)
     return WiFiSTAConnectStatus::ERROR_NETWORK_NOT_FOUND;
-  if (status == STATION_CONNECT_FAIL || status == STATION_WRONG_PASSWORD)
+  if (state == ESP8266WiFiSTAState::ERROR_FAILED)
     return WiFiSTAConnectStatus::ERROR_CONNECT_FAILED;
-  if (status == STATION_CONNECTING)
+  if (state == ESP8266WiFiSTAState::CONNECTING || state == ESP8266WiFiSTAState::ASSOCIATED)
     return WiFiSTAConnectStatus::CONNECTING;
   return WiFiSTAConnectStatus::IDLE;
 }
+
 bool WiFiComponent::wifi_scan_start_(bool passive) {
   // enable STA
   if (!this->wifi_mode_(true, {}))