From 0e108c2178231f3bd76cf39ea5d4bc4dd55dc84f Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Fri, 2 Jan 2026 14:14:52 -1000
Subject: [PATCH] [esp32] Add minimum_chip_revision setting and log chip
 revision at startup (#12696)

---
 esphome/components/esp32/__init__.py | 39 ++++++++++++++++++++++++++++
 esphome/core/application.cpp         | 16 ++++++++++++
 esphome/core/defines.h               |  1 +
 3 files changed, 56 insertions(+)

diff --git a/esphome/components/esp32/__init__.py b/esphome/components/esp32/__init__.py
index d8397a87cc..da550e58dc 100644
--- a/esphome/components/esp32/__init__.py
+++ b/esphome/components/esp32/__init__.py
@@ -85,6 +85,7 @@ CONF_ENABLE_IDF_EXPERIMENTAL_FEATURES = "enable_idf_experimental_features"
 CONF_ENABLE_LWIP_ASSERT = "enable_lwip_assert"
 CONF_ENABLE_OTA_ROLLBACK = "enable_ota_rollback"
 CONF_EXECUTE_FROM_PSRAM = "execute_from_psram"
+CONF_MINIMUM_CHIP_REVISION = "minimum_chip_revision"
 CONF_RELEASE = "release"
 
 LOG_LEVELS_IDF = [
@@ -109,6 +110,21 @@ COMPILER_OPTIMIZATIONS = {
     "SIZE": "CONFIG_COMPILER_OPTIMIZATION_SIZE",
 }
 
+# ESP32 (original) chip revision options
+# Setting minimum revision to 3.0 or higher:
+# - Reduces flash size by excluding workaround code for older chip bugs
+# - For PSRAM users: disables CONFIG_SPIRAM_CACHE_WORKAROUND, which saves significant
+#   IRAM by keeping C library functions in ROM instead of recompiling them
+# See: https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/system/chip_revision.html
+ESP32_CHIP_REVISIONS = {
+    "0.0": "CONFIG_ESP32_REV_MIN_0",
+    "1.0": "CONFIG_ESP32_REV_MIN_1",
+    "1.1": "CONFIG_ESP32_REV_MIN_1_1",
+    "2.0": "CONFIG_ESP32_REV_MIN_2",
+    "3.0": "CONFIG_ESP32_REV_MIN_3",
+    "3.1": "CONFIG_ESP32_REV_MIN_3_1",
+}
+
 # Socket limit configuration for ESP-IDF
 # ESP-IDF CONFIG_LWIP_MAX_SOCKETS has range 1-253, default 10
 DEFAULT_MAX_SOCKETS = 10  # ESP-IDF default
@@ -566,6 +582,16 @@ def final_validate(config):
                 path=[CONF_FRAMEWORK, CONF_ADVANCED, CONF_IGNORE_EFUSE_MAC_CRC],
             )
         )
+    if (
+        config[CONF_VARIANT] != VARIANT_ESP32
+        and advanced.get(CONF_MINIMUM_CHIP_REVISION) is not None
+    ):
+        errs.append(
+            cv.Invalid(
+                f"'{CONF_MINIMUM_CHIP_REVISION}' is only supported on {VARIANT_ESP32}",
+                path=[CONF_FRAMEWORK, CONF_ADVANCED, CONF_MINIMUM_CHIP_REVISION],
+            )
+        )
     if advanced[CONF_EXECUTE_FROM_PSRAM]:
         if config[CONF_VARIANT] != VARIANT_ESP32S3:
             errs.append(
@@ -694,6 +720,9 @@ FRAMEWORK_SCHEMA = cv.Schema(
                 cv.Optional(CONF_ENABLE_LWIP_ASSERT, default=True): cv.boolean,
                 cv.Optional(CONF_IGNORE_EFUSE_CUSTOM_MAC, default=False): cv.boolean,
                 cv.Optional(CONF_IGNORE_EFUSE_MAC_CRC, default=False): cv.boolean,
+                cv.Optional(CONF_MINIMUM_CHIP_REVISION): cv.one_of(
+                    *ESP32_CHIP_REVISIONS
+                ),
                 # 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.
@@ -1017,6 +1046,16 @@ async def to_code(config):
     add_idf_sdkconfig_option(
         f"CONFIG_ESPTOOLPY_FLASHSIZE_{config[CONF_FLASH_SIZE]}", True
     )
+
+    # Set minimum chip revision for ESP32 variant
+    # Setting this to 3.0 or higher reduces flash size by excluding workaround code,
+    # and for PSRAM users saves significant IRAM by keeping C library functions in ROM.
+    if variant == VARIANT_ESP32:
+        min_rev = conf[CONF_ADVANCED].get(CONF_MINIMUM_CHIP_REVISION)
+        if min_rev is not None:
+            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")
     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")
diff --git a/esphome/core/application.cpp b/esphome/core/application.cpp
index 4c9cc6b2b6..f8fa3b333e 100644
--- a/esphome/core/application.cpp
+++ b/esphome/core/application.cpp
@@ -7,6 +7,9 @@
 #ifdef USE_ESP8266
 #include <pgmspace.h>
 #endif
+#ifdef USE_ESP32
+#include <esp_chip_info.h>
+#endif
 #include "esphome/core/version.h"
 #include "esphome/core/hal.h"
 #include <algorithm>
@@ -203,6 +206,19 @@ void Application::loop() {
       ESP_LOGI(TAG, "ESPHome version " ESPHOME_VERSION " compiled on %s", build_time_str);
 #ifdef ESPHOME_PROJECT_NAME
       ESP_LOGI(TAG, "Project " ESPHOME_PROJECT_NAME " version " ESPHOME_PROJECT_VERSION);
+#endif
+#ifdef USE_ESP32
+      esp_chip_info_t chip_info;
+      esp_chip_info(&chip_info);
+      ESP_LOGI(TAG, "ESP32 Chip: %s r%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)
+      // Suggest optimization for chips that don't need the PSRAM cache workaround
+      if (chip_info.revision >= 300) {
+        ESP_LOGW(TAG, "Set minimum_chip_revision: \"%d.%d\" to reduce binary size", chip_info.revision / 100,
+                 chip_info.revision % 100);
+      }
+#endif
 #endif
     }
 
diff --git a/esphome/core/defines.h b/esphome/core/defines.h
index 579edc065a..1fddc426d4 100644
--- a/esphome/core/defines.h
+++ b/esphome/core/defines.h
@@ -166,6 +166,7 @@
 #define USE_MQTT_IDF_ENQUEUE
 #define USE_ESPHOME_TASK_LOG_BUFFER
 #define USE_OTA_ROLLBACK
+#define USE_ESP32_MIN_CHIP_REVISION_SET
 
 #define USE_BLUETOOTH_PROXY
 #define BLUETOOTH_PROXY_MAX_CONNECTIONS 3