[esp32] Apply custom eFuse MAC as base MAC for all interfaces (#18452)

esphome/components/esp32/core.cpp

@@ -2,6 +2,7 @@
 
 #include "esphome/core/application.h"
 #include "esphome/core/defines.h"
+#include "esphome/core/helpers.h"
 #include "preferences.h"
 #include <freertos/FreeRTOS.h>
 #include <freertos/task.h>
@@ -29,6 +30,13 @@ void loop_task(void *pv_params) {
 }
 
 extern "C" void app_main() {
+  // Apply the custom eFuse MAC (if burned and valid) as the base MAC before any
+  // interface (Wi-Fi, Ethernet, Bluetooth, 802.15.4) derives its address from it.
+  // The logger does not exist yet, so only log-free helpers may be used here.
+  uint8_t mac[MAC_ADDRESS_SIZE];
+  if (get_custom_mac_address(mac)) {
+    set_mac_address(mac);
+  }
   initArduino();
   esp32::setup_preferences();
 #if CONFIG_FREERTOS_UNICORE

esphome/components/esp32/helpers.cpp

@@ -71,23 +71,32 @@ static bool read_valid_mac(uint8_t *mac, esp_err_t err) { return err == ESP_OK &
 
 static constexpr size_t MAC_ADDRESS_SIZE_BITS = MAC_ADDRESS_SIZE * 8;  // 48 bits
 
+// Must not use the ESPHome logger (may run before it exists, e.g. from app_main()).
+bool get_custom_mac_address(uint8_t *mac) {
+  // has_custom_mac_address() checks the raw eFuse field, while the reads below select their
+  // method differently and may still fail (CRC), so the result must be validated again.
+  if (!has_custom_mac_address())
+    return false;
+#if defined(CONFIG_SOC_IEEE802154_SUPPORTED)
+  return read_valid_mac(mac, esp_efuse_read_field_blob(ESP_EFUSE_MAC_CUSTOM, mac, MAC_ADDRESS_SIZE_BITS));
+#else
+  return read_valid_mac(mac, esp_efuse_mac_get_custom(mac));
+#endif
+}
+
 void get_mac_address_raw(uint8_t *mac) {  // NOLINT(readability-non-const-parameter)
+  if (get_custom_mac_address(mac)) {
+    return;
+  }
 #if defined(CONFIG_SOC_IEEE802154_SUPPORTED)
   // When CONFIG_SOC_IEEE802154_SUPPORTED is defined, esp_efuse_mac_get_default
   // returns the 802.15.4 EUI-64 address, so we read directly from eFuse instead.
-  // Both paths already read raw eFuse bytes, so there is no CRC-bypass fallback
+  // This already reads raw eFuse bytes, so there is no CRC-bypass fallback
   // (unlike the non-IEEE802154 path where esp_efuse_mac_get_default does CRC checks).
-  if (has_custom_mac_address() &&
-      read_valid_mac(mac, esp_efuse_read_field_blob(ESP_EFUSE_MAC_CUSTOM, mac, MAC_ADDRESS_SIZE_BITS))) {
-    return;
-  }
   if (read_valid_mac(mac, esp_efuse_read_field_blob(ESP_EFUSE_MAC_FACTORY, mac, MAC_ADDRESS_SIZE_BITS))) {
     return;
   }
 #else
-  if (has_custom_mac_address() && read_valid_mac(mac, esp_efuse_mac_get_custom(mac))) {
-    return;
-  }
   if (read_valid_mac(mac, esp_efuse_mac_get_default(mac))) {
     return;
   }

esphome/components/wifi/wifi_component_esp_idf.cpp

@@ -140,11 +140,6 @@ void event_handler(void *arg, esp_event_base_t event_base, int32_t event_id, voi
 }
 
 void WiFiComponent::wifi_pre_setup_() {
-  uint8_t mac[MAC_ADDRESS_SIZE];
-  if (has_custom_mac_address()) {
-    get_mac_address_raw(mac);
-    set_mac_address(mac);
-  }
   // Network interface setup handled by network component
   s_wifi_event_group = xEventGroupCreate();
   if (s_wifi_event_group == nullptr) {

esphome/core/helpers.h

@@ -2089,6 +2089,11 @@ const char *get_mac_address_pretty_into_buffer(std::span<char, MAC_ADDRESS_PRETT
 #ifdef USE_ESP32
 /// Set the MAC address to use from the provided byte array (6 bytes).
 void set_mac_address(uint8_t *mac);
+
+/// Read the custom MAC address from eFuse into the provided byte array (6 bytes).
+/// Must not use the ESPHome logger (may run before it is initialized); IDF itself may still log.
+/// @return True if a valid custom MAC address was read; on false, the contents of mac are undefined.
+bool get_custom_mac_address(uint8_t *mac);
 #endif
 
 /// Check if a custom MAC address is set (ESP32 & variants)