fix: reserve Classic reconnect airtime with two Switch 2 links

ADAPTER_PARITY_PLAN.md

@@ -819,13 +819,26 @@ from 197 host requests without queue drops; the user confirmed both sides.
 Normal GATT-client busy responses now retain queued output instead of
 disconnecting the controller.
 
-Two Switch 2 BLE links plus Classic now select 30 ms Switch 2 connection
-intervals automatically; other topologies retain 7.5 ms. This trades Switch 2
-delivery latency for Classic airtime without changing HD encoding or bonds.
-Physical DualSense power-off/reconnect verified both interval transitions
-without losing the Joy-Con links. A 30-second production mixed-rumble run
-kept native DualSense streaming, with no send failures or ingress drops,
-14 Joy-Con output-stage discards and nine PCM skips. It is not lossless.
+Two or more Switch 2 BLE links now select 30 ms connection intervals even
+before Classic connects; a single Switch 2 link retains 7.5 ms. Paired and
+Individual Joy-Cons use the same physical-link policy. This trades Switch 2
+delivery latency for Classic paging and streaming airtime without changing
+HD encoding or bonds. The earlier policy waited for a Classic link and passed
+one physical power-off/reconnect check, but subsequent use exposed intermittent
+DualSense connection failures with two Joy-Cons already active. Regression
+coverage now requires airtime before Classic admission and after its departure.
+The user confirmed reconnects and actuator output/clean stops at 30 ms.
+A same-workload 15/30 ms comparison at 300 MHz rejected 15 ms for native
+haptics: it timed out around four seconds, with 111 PCM sends, 38 skips and
+one send failure. At 30 ms the full 30-second run retained all three links
+and native streaming: 1,384 PCM sends, 47 skips, no send failures or host-update/
+Switch 2 ingress drops, and seven Joy-Con output-stage drops. The isolated
+DualSense fixture delivered all 288 packets without skips. Release images keep
+30 ms; long-duration reliability remains unqualified. All 349 tests and four
+affected firmware builds passed for the preconnection policy.
+A prior 30-second production mixed-rumble run kept native DualSense streaming,
+with no send failures or ingress drops, 14 Joy-Con output-stage discards and
+nine PCM skips. It is not lossless.
 
 The native-HD checkpoint passed 289 tests and all five firmware builds; its
 40 pre-existing profiles and metadata survived. Its inventory then contained

README.md

@@ -481,13 +481,16 @@ results do **not** establish lossless arbitrary workloads or perceptual
 equivalence. All 40 profiles, names, active selections and adapter
 configuration were preserved during this upgrade.
 
-**Automatic mixed-controller scheduling:** when at least two physical Switch 2
-BLE links coexist with a Classic Bluetooth link, the firmware requests a
-30 ms connection interval for the Switch 2 links. Otherwise it requests
-7.5 ms. A merged Joy-Con pair counts as two links. Unrelated BLE controllers
+**Automatic mixed-controller scheduling:** whenever at least two physical
+Switch 2 BLE links are present, the firmware requests a 30 ms connection
+interval for those links, even before a Classic Bluetooth controller connects.
+A single Switch 2 link uses 7.5 ms. A merged Joy-Con pair counts as two links;
+Individual mode uses the same physical-link policy. Unrelated BLE controllers
 are not retimed; bonds, profiles, HD encoding and the DualSense timeout stay
-unchanged. The policy runs during connection setup, before native DualSense
-attachment, and reconciles asynchronous negotiation and topology changes.
+unchanged. The policy reconciles asynchronous negotiation and topology changes.
+Waiting for a Classic connection before reserving its airtime left a reconnect
+timing hole: DualSense could fail to connect with both Joy-Cons already active.
+Keeping 30 ms after Classic disconnect also leaves airtime for its next attempt.
 
 This trades additional Switch 2 input, gyro and rumble delivery latency for
 Classic radio time. Multiple reports can travel per connection event, so
@@ -497,13 +500,24 @@ both negotiated 30 ms and DualSense started without manual re-arming.
 A production-firmware 30-second simultaneous rumble run retained all three
 connections and native streaming: zero ingress drops or send failures,
 14 Joy-Con output-stage discards and nine DualSense PCM skips. This is not
-a lossless or long-duration qualification. Lifecycle regressions cover
-Classic arrival/departure, a missing half, handle reuse, late negotiation
-completion, clock wrap and transient request rejection.
-In the physical power-off/reconnect check, both Joy-Cons negotiated 7.5 ms
-after DualSense shut down, then 30 ms after it reconnected with PS. Their
-Bluetooth handles stayed unchanged; native DualSense streaming restarted
-automatically and sent 1,715 packets without skips at the observation point.
+a lossless or long-duration qualification. Lifecycle regressions cover airtime
+reservation before Classic arrival in Paired and Individual modes, Classic
+departure/reconnect, a missing half, handle reuse, late negotiation completion,
+clock wrap and transient request rejection.
+The earlier policy passed one physical DualSense power-off/reconnect check,
+but subsequent use exposed intermittent connection failures. The preconnection
+airtime regression fails under that policy and passes with the current one.
+The user confirmed reconnects and correct actuator output/stops with the
+preconnection 30 ms policy. A 15 ms trial also reconnected, but its native
+DualSense stream timed out even while sending silence. Under the same
+125 Hz-per-slot held-effect/silence workload at 300 MHz, 15 ms failed around
+four seconds (111 PCM packets sent, 38 skipped, one send failure); 30 ms
+completed 30 seconds (1,384 sent, 47 skipped, no send failures). All three
+controllers remained connected. The 30 ms run had zero host-update or Switch 2
+ingress drops and seven Joy-Con output-stage drops; its separate DualSense
+fixture delivered all 288 packets without skips. This supports keeping 30 ms,
+not a lossless or long-duration claim. The 15 ms trial is not the release default.
+The preconnection policy passed all 349 tests and four affected firmware builds.
 
 ### Rumble per controller
 

src/firmware/input/bluepad32_input_backend.cpp

@@ -48,7 +48,7 @@ constexpr uint32_t kDefaultPairingWindowDurationMs =
 constexpr uint32_t kPairingResetFeedbackDurationMs = 2000;
 // Bluetooth Classic units are 0.625 ms: 0x1900 = 4 seconds.
 constexpr uint16_t kClassicLinkSupervisionTimeout = 0x1900;
-// LE units are 1.25 ms. Two fast Switch 2 links starve Classic native PCM.
+// LE units are 1.25 ms. Reserve airtime for Classic paging and native PCM.
 constexpr uint16_t kSwitch2FastInterval = 6;
 constexpr uint16_t kSwitch2MixedInterval = 24;
 constexpr uint32_t kSwitch2IntervalSettleMs = 1000;
@@ -591,11 +591,11 @@ void stop_background_scan() {
         g_background_scan_active = false;
     }
 }
-// Core 1 only. Count physical links, including Classic setup, rather than
-// logical players: a merged Joy-Con pair still consumes two LE connections.
+// Core 1 only. Count physical links, not logical players: a merged Joy-Con
+// pair still consumes two LE connections. Reserve Classic airtime before an
+// incoming connection exists; waiting for its ACL handle is too late for paging.
 void apply_radio_connection_policy() {
     unsigned switch2_links = 0;
-    bool classic_link = false;
     uni_hid_device_t* ready[kSlotCount]{};
     for (const BackendSlot& slot : g_slots) {
         uni_hid_device_t* targets[] = {slot.device, slot.companion};
@@ -609,12 +609,10 @@ void apply_radio_connection_policy() {
                 // The parser requests its initial interval during setup.
                 // Do not race that request by changing a pending device here.
                 if (slot.active) ready[index] = target;
-            } else if (type == GAP_CONNECTION_ACL) {
-                classic_link = true;
             }
         }
     }
-    const uint16_t desired = switch2_links >= 2 && classic_link
+    const uint16_t desired = switch2_links >= 2
                                  ? kSwitch2MixedInterval
                                  : kSwitch2FastInterval;
     const uint32_t now_ms = btstack_run_loop_get_time_ms();

tests/bluepad32_backend_lifecycle_test.cpp

@@ -3034,33 +3034,37 @@ void test_switch2_admission() {
             "Pro2 must preserve vertical normal controls and ingest remappable extras");
 }
 
-void test_switch2_radio_policy() {
+void test_switch2_radio_policy(bool individual) {
     start_backend();
+    if (individual) set_runtime_joycon_mode(JoyConMode::kIndividual);
     auto left = switch2_device(0, UNI_SW2_JOYCON_L_PID);
     auto right = switch2_device(1, UNI_SW2_JOYCON_R_PID);
     auto classic = device(2, true, UNI_BT_CONN_PROTOCOL_BR_EDR);
     auto other_ble = device(3, true, UNI_BT_CONN_PROTOCOL_BLE);
     ready_switch2(left);
+    require(negotiated_intervals[left.conn.handle] == 6,
+            "a single Switch2 link must retain fast scheduling");
     ready_switch2(right);
+    require(incoming_connections &&
+                negotiated_intervals[left.conn.handle] == 24 &&
+                negotiated_intervals[right.conn.handle] == 24,
+            "two Switch2 links must reserve Classic reconnect airtime before a Classic device exists");
     platform_on_device_connected(&other_ble);
     require(platform_on_device_ready(&other_ble) == UNI_ERROR_SUCCESS,
             "unrelated BLE controller must join");
-    require(negotiated_intervals[left.conn.handle] == 6 &&
-                negotiated_intervals[right.conn.handle] == 6,
-            "a pair without Classic must retain fast intervals");
     platform_on_device_connected(&classic);
     require(negotiated_intervals[left.conn.handle] == 24 &&
                 negotiated_intervals[right.conn.handle] == 24 &&
                 negotiated_intervals[other_ble.conn.handle] == 6,
-            "Classic setup must relax both physical halves before native attachment, not unrelated BLE");
+            "Classic setup must retain reconnect airtime without retiming unrelated BLE");
     require(platform_on_device_ready(&classic) == UNI_ERROR_SUCCESS,
             "Classic controller must complete setup alongside the pair");
     const auto pair = slot_snapshot(0);
     platform_on_device_disconnected(&classic);
-    require(negotiated_intervals[left.conn.handle] == 6 &&
-                negotiated_intervals[right.conn.handle] == 6 &&
+    require(negotiated_intervals[left.conn.handle] == 24 &&
+                negotiated_intervals[right.conn.handle] == 24 &&
                 slot_snapshot(0).connection_generation == pair.connection_generation,
-            "Classic departure must restore fast intervals without rebinding the pair");
+            "Classic departure must preserve reconnect airtime without rebinding the pair");
     platform_on_device_connected(&classic);
     require(platform_on_device_ready(&classic) == UNI_ERROR_SUCCESS,
             "Classic reconnect must complete");
@@ -3090,22 +3094,20 @@ void test_switch2_radio_settling() {
             "pending Switch2 setup must retain ownership of its initial interval");
     require(platform_on_device_ready(&right) == UNI_ERROR_SUCCESS,
             "second Switch2 connection must become ready");
-    platform_on_device_disconnected(&classic);
-    // The controller completes the old update after the topology reversed.
+    platform_on_device_disconnected(&right);
+    // The surviving controller completes the old update after losing its mate.
     for (auto* half : {&left, &right}) {
         negotiated_intervals[half->conn.handle] = pending_intervals[half->conn.handle];
     }
     now_ms += 50;
     process_configuration_timer(&g_configuration_timer);
-    for (auto* half : {&left, &right}) {
-        negotiated_intervals[half->conn.handle] = pending_intervals[half->conn.handle];
-        require(negotiated_intervals[half->conn.handle] == 6,
-                "late mixed-mode completion must not strand a pair at slow intervals across clock wrap");
-    }
+    negotiated_intervals[left.conn.handle] = pending_intervals[left.conn.handle];
+    require(negotiated_intervals[left.conn.handle] == 6,
+            "late coexistence update must not strand a solo at slow intervals across clock wrap");
     process_configuration_timer(&g_configuration_timer);
     defer_interval_updates = false;
     reject_interval_updates = true;
-    platform_on_device_connected(&classic);
+    ready_switch2(right);
     const unsigned attempts = interval_requests[left.conn.handle];
     now_ms += 999;
     process_configuration_timer(&g_configuration_timer);
@@ -5477,7 +5479,9 @@ int main(int argc, char** argv) {
     } else if (scenario == "switch2-admission") {
         test_switch2_admission();
     } else if (scenario == "switch2-radio-policy") {
-        test_switch2_radio_policy();
+        test_switch2_radio_policy(false);
+    } else if (scenario == "switch2-radio-individual") {
+        test_switch2_radio_policy(true);
     } else if (scenario == "switch2-radio-settling") {
         test_switch2_radio_settling();
     } else if (scenario == "switch2-mate-reconnect") {

tests/test_bluepad32_backend_lifecycle_native.py

@@ -127,6 +127,7 @@ def test_bluepad32_backend_lifecycle_native(tmp_path: Path) -> None:
             "switch2-pair-replacement",
             "switch2-admission",
             "switch2-radio-policy",
+            "switch2-radio-individual",
             "switch2-radio-settling",
             "switch2-mate-reconnect",
             "switch2-mate-pending",