From 6c0d5426fc1c2c9a00e570cf11ee69d9e02158ec Mon Sep 17 00:00:00 2001
From: Matthias Ringwald <matthias@ringwald.ch>
Date: Mon, 24 Jan 2022 18:10:16 +0100
Subject: [PATCH] hci: ENABLE_HCI_SERIALIZED_CONTROLLER_OPERATIONS serializes
 Inquiry, Remote Name Request and Create Connection operations

---
 CHANGELOG.md                       |  1 +
 doc/manual/docs-template/how_to.md |  1 +
 src/hci.c                          | 56 +++++++++++++++++++++++++-----
 3 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3df446463..6fe8f36a0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## Unreleased
 
 ### Added
+- HCI: ENABLE_HCI_SERIALIZED_CONTROLLER_OPERATIONS serializes Inquiry, Remote Name Request and Create Connection operations
 - GAP: support extended advertising with ENABLE_LE_EXTENDED_ADVERTISING
 - ATT DB: provide gatt_server_get_handle_range_for_service_with_uuid16 to find included service within handle range
 - GATT Service: Audio Input Control Service Server (AICS 1.0)
diff --git a/doc/manual/docs-template/how_to.md b/doc/manual/docs-template/how_to.md
index d5593f2de..f1bd0fb04 100644
--- a/doc/manual/docs-template/how_to.md
+++ b/doc/manual/docs-template/how_to.md
@@ -100,6 +100,7 @@ ENABLE_L2CAP_ENHANCED_RETRANSMISSION_MODE | Enable Enhanced Retransmission Mode
 ENABLE_L2CAP_LE_CREDIT_BASED_FLOW_CONTROL_MODE | Enable LE credit-based flow-control mode for L2CAP channels
 ENABLE_L2CAP_ENHANCED_CREDIT_BASED_FLOW_CONTROL_MODE | Enable Enhanced credit-based flow-control mode for L2CAP Channels
 ENABLE_HCI_CONTROLLER_TO_HOST_FLOW_CONTROL | Enable HCI Controller to Host Flow Control, see below
+ENABLE_HCI_SERIALIZED_CONTROLLER_OPERATIONS | Serialize Inquiry, Remote Name Request, and Create Connection operations
 ENABLE_ATT_DELAYED_RESPONSE      | Enable support for delayed ATT operations, see [GATT Server](profiles/#sec:GATTServerProfile)
 ENABLE_BCM_PCM_WBS               | Enable support for Wide-Band Speech codec in BCM controller, requires ENABLE_SCO_OVER_PCM
 ENABLE_CC256X_ASSISTED_HFP       | Enable support for Assisted HFP mode in CC256x Controller, requires ENABLE_SCO_OVER_PCM
diff --git a/src/hci.c b/src/hci.c
index 7f05f99d6..1b38c9a1c 100644
--- a/src/hci.c
+++ b/src/hci.c
@@ -4517,6 +4517,31 @@ static bool hci_run_acl_fragments(void){
 }
 
 #ifdef ENABLE_CLASSIC
+
+#ifdef ENABLE_HCI_SERIALIZED_CONTROLLER_OPERATIONS
+static bool hci_classic_operation_active(void) {
+    if (hci_stack->inquiry_state >= GAP_INQUIRY_STATE_W4_ACTIVE){
+        return true;
+    }
+    if (hci_stack->remote_name_state == GAP_REMOTE_NAME_STATE_W4_COMPLETE){
+        return true;
+    }
+    btstack_linked_item_t * it;
+    for (it = (btstack_linked_item_t *) hci_stack->connections; it != NULL; it = it->next) {
+        hci_connection_t *connection = (hci_connection_t *) it;
+        switch (connection->state) {
+            case SENT_CREATE_CONNECTION:
+            case SENT_CANCEL_CONNECTION:
+            case SENT_DISCONNECT:
+                return true;
+            default:
+                break;
+        }
+    }
+    return false;
+}
+#endif
+
 static bool hci_run_general_gap_classic(void){
 
     // assert stack is working and classic is active
@@ -4538,10 +4563,15 @@ static bool hci_run_general_gap_classic(void){
 
     // start/stop inquiry
     if ((hci_stack->inquiry_state >= GAP_INQUIRY_DURATION_MIN) && (hci_stack->inquiry_state <= GAP_INQUIRY_DURATION_MAX)){
-        uint8_t duration = hci_stack->inquiry_state;
-        hci_stack->inquiry_state = GAP_INQUIRY_STATE_W4_ACTIVE;
-        hci_send_cmd(&hci_inquiry, hci_stack->inquiry_lap, duration, 0);
-        return true;
+#ifdef ENABLE_HCI_SERIALIZED_CONTROLLER_OPERATIONS
+        if (hci_classic_operation_active() == false)
+#endif
+        {
+            uint8_t duration = hci_stack->inquiry_state;
+            hci_stack->inquiry_state = GAP_INQUIRY_STATE_W4_ACTIVE;
+            hci_send_cmd(&hci_inquiry, hci_stack->inquiry_lap, duration, 0);
+            return true;
+        }
     }
     if (hci_stack->inquiry_state == GAP_INQUIRY_STATE_W2_CANCEL){
         hci_stack->inquiry_state = GAP_INQUIRY_STATE_W4_CANCELLED;
@@ -4550,10 +4580,15 @@ static bool hci_run_general_gap_classic(void){
     }
     // remote name request
     if (hci_stack->remote_name_state == GAP_REMOTE_NAME_STATE_W2_SEND){
-        hci_stack->remote_name_state = GAP_REMOTE_NAME_STATE_W4_COMPLETE;
-        hci_send_cmd(&hci_remote_name_request, hci_stack->remote_name_addr,
-                     hci_stack->remote_name_page_scan_repetition_mode, 0, hci_stack->remote_name_clock_offset);
-        return true;
+#ifdef ENABLE_HCI_SERIALIZED_CONTROLLER_OPERATIONS
+        if (hci_classic_operation_active() == false)
+#endif
+        {
+            hci_stack->remote_name_state = GAP_REMOTE_NAME_STATE_W4_COMPLETE;
+            hci_send_cmd(&hci_remote_name_request, hci_stack->remote_name_addr,
+                         hci_stack->remote_name_page_scan_repetition_mode, 0, hci_stack->remote_name_clock_offset);
+            return true;
+        }
     }
 #ifdef ENABLE_CLASSIC_PAIRING_OOB
     // Local OOB data
@@ -5757,6 +5792,11 @@ uint8_t hci_send_cmd_packet(uint8_t *packet, int size){
                     // create connection triggered in disconnect complete event, let's do it now
                     break;
                 case SEND_CREATE_CONNECTION:
+#ifdef ENABLE_HCI_SERIALIZED_CONTROLLER_OPERATIONS
+                    if (hci_classic_operation_active()){
+                        return ERROR_CODE_SUCCESS;
+                    }
+#endif
                     // connection created by hci, e.g. dedicated bonding, but not executed yet, let's do it now
                     break;
                 default: