fix(nimble): Add support for shorter connection intervals

components/bt/common/Kconfig.in

@@ -6,6 +6,21 @@ config BT_ALARM_MAX_NUM
         This option decides the maximum number of alarms which
         could be used by Bluetooth host.
 
+config BT_BLE_HOST_ALLOW_SUB_SPEC_MIN_CONN_INT
+    bool "Allow BLE connection interval below Bluetooth Core Spec minimum (disable host check)"
+    depends on BT_BLE_ENABLED || BT_NIMBLE_ENABLED
+    default n
+    help
+        When enabled, BLE host-side validation accepts connection interval
+        values below the Bluetooth Core Specification minimum of 0x0006
+        (7.5 ms), down to non-zero values. The BLE controller still enforces
+        what is actually supported in hardware and firmware.
+
+        End users should NOT set this option directly. In typical IDF builds it
+        follows the active Controller integration when that Controller supports
+        this mode; use the Controller's own configuration instead of toggling
+        this host symbol manually.
+
 choice BT_SMP_CRYPTO_STACK
     prompt "SMP cryptographic stack"
     depends on (BT_BLE_SMP_ENABLE || BT_SMP_ENABLE || BT_NIMBLE_SECURITY_ENABLE || BT_LE_SECURITY_ENABLE)

components/bt/controller/esp32c3/Kconfig.in

@@ -564,7 +564,7 @@ config BT_CTRL_CHECK_CONNECT_IND_ACCESS_ADDRESS
 config BT_CTRL_BLE_MIN_CONN_INTERVAL_ENABLE
     bool "Allow BLE connection interval below the spec minimum"
     default y
-    select BT_BLE_HOST_ALLOW_SUB_SPEC_MIN_CONN_INT if BT_BLUEDROID_ENABLED
+    select BT_BLE_HOST_ALLOW_SUB_SPEC_MIN_CONN_INT if BT_BLUEDROID_ENABLED || BT_NIMBLE_ENABLED
     help
         Enabling this option allows the BLE controller to use a connection interval
         smaller than the Bluetooth Core specification minimum of 7.5 ms. On
@@ -579,12 +579,9 @@ config BT_CTRL_BLE_MIN_CONN_INTERVAL_ENABLE
         This option is enabled by default. Disable it to stay compliant with the BLE
         specification (minimum connection interval 7.5 ms).
 
-        Host stack: When Bluedroid is the BLE host, enabling this option also selects
-        BT_BLE_HOST_ALLOW_SUB_SPEC_MIN_CONN_INT so the host accepts connection
-        intervals below the spec minimum. NimBLE host does not provide equivalent
-        support yet; it is planned for a future release. Until then, use Bluedroid
-        if you need coordinated host and controller behavior for sub-minimum
-        intervals.
+        Host stack: Enabling this option also selects
+        BT_BLE_HOST_ALLOW_SUB_SPEC_MIN_CONN_INT so the active BLE host accepts
+        connection intervals below the spec minimum.
 
 menu "Controller debug log Options (Experimental)"
     config BT_CTRL_LE_LOG_EN

components/bt/host/bluedroid/Kconfig.in

@@ -1245,23 +1245,6 @@ config BT_BLE_RPA_TIMEOUT
         This set RPA timeout of Controller and Host.
         Default is 900 s (15 minutes). Range is 1 s to 1 hour (3600 s).
 
-config BT_BLE_HOST_ALLOW_SUB_SPEC_MIN_CONN_INT
-    bool "Allow BLE connection interval below Bluetooth Core Spec minimum (disable host check)"
-    depends on BT_BLE_ENABLED
-    default n
-    help
-        When enabled, the Bluedroid host skips the minimum BLE connection
-        interval validation (Bluetooth Core Spec minimum is 0x0006 / 7.5 ms)
-        and accepts any non-zero interval value from the application. The
-        BLE controller then enforces what is actually allowed; how small the
-        connection interval may be depends on controller capability and its
-        own configuration, not on this host option text.
-
-        End users should NOT set this option directly. In typical IDF builds it
-        follows the active Controller integration when that Controller supports
-        this mode; use the Controller's own configuration (menu entries and symbol
-        names differ by chip) instead of toggling this host symbol manually.
-
 menuconfig BT_BLE_50_FEATURES_SUPPORTED
     bool "Enable BLE 5.0 and above features(please disable BLE 4.2 if enable BLE 5.0)"
     depends on (BT_BLE_ENABLED && ((BT_CONTROLLER_ENABLED && SOC_BLE_50_SUPPORTED) || BT_CONTROLLER_DISABLED))