[esp32_ble] Enable CONFIG_BT_RELEASE_IRAM on ESP32-C2 (#14109)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

esphome/components/esp32_ble/__init__.py

@@ -9,6 +9,7 @@ from esphome import automation
 import esphome.codegen as cg
 from esphome.components import socket
 from esphome.components.esp32 import add_idf_sdkconfig_option, const, get_esp32_variant
+from esphome.components.esp32.const import VARIANT_ESP32C2
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_ENABLE_ON_BOOT,
@@ -387,6 +388,15 @@ def final_validation(config):
                 f"Name '{name}' is too long, maximum length is {max_length} characters"
             )
 
+    # ESP32-C2 has very limited RAM (~272KB). Without releasing BLE IRAM,
+    # esp_bt_controller_init fails with ESP_ERR_NO_MEM.
+    # CONFIG_BT_RELEASE_IRAM changes the memory layout so IRAM and DRAM share
+    # space more flexibly, giving the BT controller enough contiguous memory.
+    # This requires CONFIG_ESP_SYSTEM_PMP_IDRAM_SPLIT to be disabled.
+    if get_esp32_variant() == VARIANT_ESP32C2:
+        add_idf_sdkconfig_option("CONFIG_BT_RELEASE_IRAM", True)
+        add_idf_sdkconfig_option("CONFIG_ESP_SYSTEM_PMP_IDRAM_SPLIT", False)
+
     # Set GATT Client/Server sdkconfig options based on which components are loaded
     full_config = fv.full_config.get()
 

tests/components/esp32_ble/test.esp32-c2-idf.yaml

@@ -0,0 +1,5 @@
+<<: !include common.yaml
+
+esp32_ble:
+  io_capability: keyboard_only
+  disable_bt_logs: false