[esp32] Add sram1_as_iram option and bootloader version detection (#14874)

esphome/components/esp32/__init__.py

@@ -97,6 +97,7 @@ CONF_ENABLE_LWIP_ASSERT = "enable_lwip_assert"
 CONF_EXECUTE_FROM_PSRAM = "execute_from_psram"
 CONF_MINIMUM_CHIP_REVISION = "minimum_chip_revision"
 CONF_RELEASE = "release"
+CONF_SRAM1_AS_IRAM = "sram1_as_iram"
 CONF_SUBTYPE = "subtype"
 
 ARDUINO_FRAMEWORK_NAME = "framework-arduinoespressif32"
@@ -884,6 +885,13 @@ def final_validate(config):
                 path=[CONF_FRAMEWORK, CONF_ADVANCED, CONF_MINIMUM_CHIP_REVISION],
             )
         )
+    if config[CONF_VARIANT] != VARIANT_ESP32 and advanced[CONF_SRAM1_AS_IRAM]:
+        errs.append(
+            cv.Invalid(
+                f"'{CONF_SRAM1_AS_IRAM}' is only supported on {VARIANT_ESP32}",
+                path=[CONF_FRAMEWORK, CONF_ADVANCED, CONF_SRAM1_AS_IRAM],
+            )
+        )
     if (
         config[CONF_VARIANT] != VARIANT_ESP32P4
         and config.get(CONF_ENGINEERING_SAMPLE) is not None
@@ -1131,6 +1139,7 @@ FRAMEWORK_SCHEMA = cv.Schema(
                 cv.Optional(CONF_MINIMUM_CHIP_REVISION): cv.one_of(
                     *ESP32_CHIP_REVISIONS
                 ),
+                cv.Optional(CONF_SRAM1_AS_IRAM, default=False): cv.boolean,
                 # DHCP server is needed for WiFi AP mode. When WiFi component is used,
                 # it will handle disabling DHCP server when AP is not configured.
                 # Default to false (disabled) when WiFi is not used.
@@ -1655,6 +1664,16 @@ async def to_code(config):
             for rev, flag in ESP32_CHIP_REVISIONS.items():
                 add_idf_sdkconfig_option(flag, rev == min_rev)
             cg.add_define("USE_ESP32_MIN_CHIP_REVISION_SET")
+
+    # Use SRAM1 region as IRAM on ESP32 (original) variant
+    # This provides an additional 40KB of IRAM by using SRAM1 memory that was previously
+    # reserved for bootloader DRAM. Requires a bootloader from ESP-IDF v5.1 or later.
+    # WARNING: If the device has an old bootloader (pre-v5.1), the app will fail to boot.
+    # A USB flash will update the bootloader automatically. OTA updates do not.
+    # See: https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-guides/performance/ram-usage.html
+    if variant == VARIANT_ESP32 and conf[CONF_ADVANCED][CONF_SRAM1_AS_IRAM]:
+        add_idf_sdkconfig_option("CONFIG_ESP_SYSTEM_ESP32_SRAM1_REGION_AS_IRAM", True)
+        cg.add_define("USE_ESP32_SRAM1_AS_IRAM")
     add_idf_sdkconfig_option("CONFIG_PARTITION_TABLE_SINGLE_APP", False)
     add_idf_sdkconfig_option("CONFIG_PARTITION_TABLE_CUSTOM", True)
     add_idf_sdkconfig_option("CONFIG_PARTITION_TABLE_CUSTOM_FILENAME", "partitions.csv")

esphome/core/application.cpp

@@ -9,6 +9,8 @@
 #endif
 #ifdef USE_ESP32
 #include <esp_chip_info.h>
+#include <esp_ota_ops.h>
+#include <esp_bootloader_desc.h>
 #endif
 #ifdef USE_LWIP_FAST_SELECT
 #include "esphome/core/lwip_fast_select.h"
@@ -167,19 +169,49 @@ void Application::process_dump_config_() {
     esp_chip_info(&chip_info);
     ESP_LOGI(TAG, "ESP32 Chip: %s rev%d.%d, %d core(s)", ESPHOME_VARIANT, chip_info.revision / 100,
              chip_info.revision % 100, chip_info.cores);
-#if defined(USE_ESP32_VARIANT_ESP32) && !defined(USE_ESP32_MIN_CHIP_REVISION_SET)
+#if defined(USE_ESP32_VARIANT_ESP32) && (!defined(USE_ESP32_MIN_CHIP_REVISION_SET) || !defined(USE_ESP32_SRAM1_AS_IRAM))
-    // Suggest optimization for chips that don't need the PSRAM cache workaround
+    static const char *const ESP32_ADVANCED_PATH = "under esp32 > framework > advanced";
-    if (chip_info.revision >= 300) {
-#ifdef USE_PSRAM
-      ESP_LOGW(TAG, "Set minimum_chip_revision: \"%d.%d\" to save ~10KB IRAM", chip_info.revision / 100,
-               chip_info.revision % 100);
-#else
-      ESP_LOGW(TAG, "Set minimum_chip_revision: \"%d.%d\" to reduce binary size", chip_info.revision / 100,
-               chip_info.revision % 100);
 #endif
+#if defined(USE_ESP32_VARIANT_ESP32) && !defined(USE_ESP32_MIN_CHIP_REVISION_SET)
+    {
+      // Suggest optimization for chips that don't need the PSRAM cache workaround
+      if (chip_info.revision >= 300) {
+#ifdef USE_PSRAM
+        ESP_LOGW(TAG, "Chip rev >= 3.0 detected. Set minimum_chip_revision: \"%d.%d\" %s to save ~10KB IRAM",
+                 chip_info.revision / 100, chip_info.revision % 100, ESP32_ADVANCED_PATH);
+#else
+        ESP_LOGW(TAG, "Chip rev >= 3.0 detected. Set minimum_chip_revision: \"%d.%d\" %s to reduce binary size",
+                 chip_info.revision / 100, chip_info.revision % 100, ESP32_ADVANCED_PATH);
+#endif
+      }
     }
 #endif
+    {
+      // esp_bootloader_desc_t is available in ESP-IDF >= 5.2; if readable the bootloader is modern.
+      //
+      // Design decision: We intentionally do NOT mention sram1_as_iram when the bootloader is too old.
+      // Enabling sram1_as_iram with an old bootloader causes a hard brick (device fails to boot,
+      // requires USB reflash to recover). Users don't always read warnings carefully, so we only
+      // suggest the option once we've confirmed the bootloader can handle it. In practice this
+      // means a user with an old bootloader may need to flash twice: once via USB to update the
+      // bootloader (they'll see the suggestion on next boot), then OTA with sram1_as_iram: true.
+      // Two flashes is a better outcome than a bricked device.
+      esp_bootloader_desc_t boot_desc;
+      if (esp_ota_get_bootloader_description(nullptr, &boot_desc) != ESP_OK) {
+#ifdef USE_ESP32_VARIANT_ESP32
+        ESP_LOGW(TAG, "Bootloader too old for OTA rollback and SRAM1 as IRAM (+40KB). "
+                      "Flash via USB once to update the bootloader");
+#else
+        ESP_LOGW(TAG, "Bootloader too old for OTA rollback. Flash via USB once to update the bootloader");
 #endif
+      }
+#if defined(USE_ESP32_VARIANT_ESP32) && !defined(USE_ESP32_SRAM1_AS_IRAM)
+      else {
+        ESP_LOGW(TAG, "Bootloader supports SRAM1 as IRAM (+40KB). Set sram1_as_iram: true %s", ESP32_ADVANCED_PATH);
+      }
+#endif
+    }
+#endif  // USE_ESP32
   }
 
   this->components_[this->dump_config_at_]->call_dump_config_();

esphome/core/defines.h

@@ -202,6 +202,7 @@
 #define USE_ESPHOME_TASK_LOG_BUFFER
 #define USE_OTA_ROLLBACK
 #define USE_ESP32_MIN_CHIP_REVISION_SET
+#define USE_ESP32_SRAM1_AS_IRAM
 
 #define USE_BLUETOOTH_PROXY
 #define BLUETOOTH_PROXY_MAX_CONNECTIONS 3

tests/components/esp32/test.esp32-idf.yaml

@@ -19,6 +19,7 @@ esp32:
       disable_mbedtls_pkcs7: true
       disable_regi2c_in_iram: true
       disable_fatfs: true
+      sram1_as_iram: true
 
 wifi:
   ssid: MySSID