move flow control to btc layer

defer free slot in btc layer when receive BTA_JV_RFCOMM_CLOSE_EVT

components/bt/common/osi/include/osi/list.h

@@ -22,6 +22,10 @@ list_t *list_new(list_free_cb callback);
 
 
 list_node_t *list_free_node(list_t *list, list_node_t *node);
+
+// similar with list_free_node, this function doesn't free the node data
+list_node_t *list_delete_node(list_t *list, list_node_t *node);
+
 // Frees the list. This function accepts NULL as an argument, in which case it
 // behaves like a no-op.
 void list_free(list_t *list);
@@ -75,6 +79,9 @@ bool list_append(list_t *list, void *data);
 
 bool list_remove(list_t *list, void *data);
 
+// similar with list_remove, but do not free the node data
+bool list_delete(list_t *list, void *data);
+
 // Removes all elements in the list. Calling this function will return the list to the
 // same state it was in after |list_new|. |list| may not be NULL.
 void list_clear(list_t *list);

components/bt/common/osi/list.c

@@ -186,6 +186,36 @@ bool list_remove(list_t *list, void *data)
     return false;
 }
 
+bool list_delete(list_t *list, void *data)
+{
+    assert(list != NULL);
+    assert(data != NULL);
+
+    if (list_is_empty(list)) {
+        return false;
+    }
+
+    if (list->head->data == data) {
+        list_node_t *next = list_delete_node(list, list->head);
+        if (list->tail == list->head) {
+            list->tail = next;
+        }
+        list->head = next;
+        return true;
+    }
+
+    for (list_node_t *prev = list->head, *node = list->head->next; node; prev = node, node = node->next)
+        if (node->data == data) {
+            prev->next = list_delete_node(list, node);
+            if (list->tail == node) {
+                list->tail = prev;
+            }
+            return true;
+        }
+
+    return false;
+}
+
 void list_clear(list_t *list)
 {
     assert(list != NULL);
@@ -251,3 +281,17 @@ list_node_t *list_free_node(list_t *list, list_node_t *node)
 
     return next;
 }
+
+// remove the element from list but do not free the node data
+list_node_t *list_delete_node(list_t *list, list_node_t *node)
+{
+    assert(list != NULL);
+    assert(node != NULL);
+
+    list_node_t *next = node->next;
+
+    osi_free(node);
+    --list->length;
+
+    return next;
+}

components/bt/host/bluedroid/bta/include/bta/bta_jv_api.h

@@ -297,6 +297,7 @@ typedef struct {
     tBTA_JV_STATUS  status;      /* Whether the operation succeeded or failed. */
     UINT32          port_status; /* PORT status */
     UINT32          handle;      /* The connection handle */
+    void            *slot;       /* slot pointer */
     BOOLEAN         async;       /* FALSE, if local initiates disconnect */
 } tBTA_JV_RFCOMM_CLOSE;
 
@@ -894,6 +895,18 @@ extern tBTA_JV_STATUS BTA_JvRfcommReady(UINT32 handle, UINT32 *p_data_size);
 *******************************************************************************/
 extern tBTA_JV_STATUS BTA_JvRfcommWrite(UINT32 handle, UINT32 req_id, int len, UINT8 *p_data);
 
+/*******************************************************************************
+**
+** Function         BTA_JvRfcommFlowControl
+**
+** Description      This function gives the credit to the peer
+**
+** Returns          BTA_JV_SUCCESS, if the request is being processed.
+**                  BTA_JV_FAILURE, otherwise.
+**
+*******************************************************************************/
+extern tBTA_JV_STATUS BTA_JvRfcommFlowControl(UINT32 handle, UINT16 credits_given);
+
 /*******************************************************************************
  **
  ** Function    BTA_JVSetPmProfile

components/bt/host/bluedroid/bta/jv/bta_jv_act.c

@@ -1688,6 +1688,7 @@ static void bta_jv_port_mgmt_cl_cback(UINT32 code, UINT16 port_handle)
         evt_data.rfc_close.status = BTA_JV_FAILURE;
         evt_data.rfc_close.port_status = code;
         evt_data.rfc_close.async = TRUE;
+        evt_data.rfc_close.slot = NULL;
         if (p_pcb->state == BTA_JV_ST_CL_CLOSING) {
             evt_data.rfc_close.async = FALSE;
             evt_data.rfc_close.status = BTA_JV_SUCCESS;
@@ -1871,6 +1872,7 @@ void bta_jv_rfcomm_close(tBTA_JV_MSG *p_data)
         evt_data.rfc_close.port_status = PORT_LOCAL_CLOSED;
         evt_data.rfc_close.handle = cc->handle;
         evt_data.rfc_close.async = TRUE;
+        evt_data.rfc_close.slot = NULL;
         if (p_pcb && (p_pcb->state == BTA_JV_ST_SR_LISTEN ||
                       p_pcb->state == BTA_JV_ST_SR_OPEN ||
                       p_pcb->state == BTA_JV_ST_CL_OPEN ||
@@ -1960,6 +1962,7 @@ static void bta_jv_port_mgmt_sr_cback(UINT32 code, UINT16 port_handle)
         evt_data.rfc_close.status = BTA_JV_FAILURE;
         evt_data.rfc_close.async = TRUE;
         evt_data.rfc_close.port_status = code;
+        evt_data.rfc_close.slot = NULL;
         p_pcb->cong = FALSE;
 
         tBTA_JV_RFCOMM_CBACK    *p_cback = p_cb->p_cback;
@@ -2275,6 +2278,23 @@ void bta_jv_rfcomm_write(tBTA_JV_MSG *p_data)
 
 }
 
+/*******************************************************************************
+**
+** Function     bta_jv_rfcomm_flow_control
+**
+** Description  give credits to the peer
+**
+** Returns      void
+**
+*******************************************************************************/
+void bta_jv_rfcomm_flow_control(tBTA_JV_MSG *p_data)
+{
+    tBTA_JV_API_RFCOMM_FLOW_CONTROL *fc = &(p_data->rfcomm_fc);
+
+    tBTA_JV_PCB *p_pcb = fc->p_pcb;
+    PORT_FlowControl_GiveCredit(p_pcb->port_handle, TRUE, fc->credits_given);
+}
+
 /*******************************************************************************
  **
  ** Function     bta_jv_set_pm_profile

components/bt/host/bluedroid/bta/jv/bta_jv_api.c

@@ -1136,6 +1136,38 @@ tBTA_JV_STATUS BTA_JvRfcommWrite(UINT32 handle, UINT32 req_id, int len, UINT8 *p
     return (status);
 }
 
+/*******************************************************************************
+**
+** Function         BTA_JvRfcommFlowControl
+**
+** Description      This function gives credits to the peer
+**
+** Returns          BTA_JV_SUCCESS, if the request is being processed.
+**                  BTA_JV_FAILURE, otherwise.
+**
+*******************************************************************************/
+tBTA_JV_STATUS BTA_JvRfcommFlowControl(UINT32 handle, UINT16 credits_given)
+{
+    tBTA_JV_STATUS status = BTA_JV_FAILURE;
+    tBTA_JV_API_RFCOMM_FLOW_CONTROL *p_msg;
+    UINT32  hi = ((handle & BTA_JV_RFC_HDL_MASK) & ~BTA_JV_RFCOMM_MASK) - 1;
+    UINT32  si = BTA_JV_RFC_HDL_TO_SIDX(handle);
+
+    APPL_TRACE_API( "BTA_JvRfcommFlowControl");
+    APPL_TRACE_DEBUG( "handle:0x%x, hi:%d, si:%d", handle, hi, si);
+    if (hi < BTA_JV_MAX_RFC_CONN && bta_jv_cb.rfc_cb[hi].p_cback &&
+            si < BTA_JV_MAX_RFC_SR_SESSION && bta_jv_cb.rfc_cb[hi].rfc_hdl[si] &&
+            (p_msg = (tBTA_JV_API_RFCOMM_FLOW_CONTROL *)osi_malloc(sizeof(tBTA_JV_API_RFCOMM_FLOW_CONTROL))) != NULL) {
+        p_msg->hdr.event = BTA_JV_API_RFCOMM_FLOW_CONTROL_EVT;
+        p_msg->p_cb = &bta_jv_cb.rfc_cb[hi];
+        p_msg->p_pcb = &bta_jv_cb.port_cb[p_msg->p_cb->rfc_hdl[si] - 1];
+        p_msg->credits_given = credits_given;
+        APPL_TRACE_API( "credits given %d", credits_given);
+        bta_sys_sendmsg(p_msg);
+        status = BTA_JV_SUCCESS;
+    }
+    return (status);
+}
 
 /*******************************************************************************
  **

components/bt/host/bluedroid/bta/jv/bta_jv_main.c

@@ -68,6 +68,7 @@ const tBTA_JV_ACTION bta_jv_action[] = {
     bta_jv_rfcomm_stop_server,      /* BTA_JV_API_RFCOMM_STOP_SERVER_EVT */
     bta_jv_rfcomm_read,             /* BTA_JV_API_RFCOMM_READ_EVT */
     bta_jv_rfcomm_write,            /* BTA_JV_API_RFCOMM_WRITE_EVT */
+    bta_jv_rfcomm_flow_control,     /* BTA_JV_API_RFCOMM_FLOW_CONTROL_EVT */
     bta_jv_set_pm_profile,          /* BTA_JV_API_SET_PM_PROFILE_EVT */
     bta_jv_change_pm_state,         /* BTA_JV_API_PM_STATE_CHANGE_EVT */
 #if BTA_JV_L2CAP_INCLUDED

components/bt/host/bluedroid/bta/jv/include/bta_jv_int.h

@@ -62,6 +62,7 @@ enum {
     BTA_JV_API_RFCOMM_STOP_SERVER_EVT,
     BTA_JV_API_RFCOMM_READ_EVT,
     BTA_JV_API_RFCOMM_WRITE_EVT,
+    BTA_JV_API_RFCOMM_FLOW_CONTROL_EVT,
     BTA_JV_API_SET_PM_PROFILE_EVT,
     BTA_JV_API_PM_STATE_CHANGE_EVT,
 #if BTA_JV_L2CAP_INCLUDED
@@ -309,6 +310,14 @@ typedef struct {
     tBTA_JV_PCB     *p_pcb;
 } tBTA_JV_API_RFCOMM_WRITE;
 
+/* data type for BTA_JV_API_RFCOMM_FLOW_CONTROL_EVT */
+typedef struct {
+    BT_HDR      hdr;
+    tBTA_JV_RFC_CB  *p_cb;
+    tBTA_JV_PCB     *p_pcb;
+    UINT16      credits_given;
+} tBTA_JV_API_RFCOMM_FLOW_CONTROL;
+
 /* data type for BTA_JV_API_RFCOMM_CLOSE_EVT */
 typedef struct {
     BT_HDR          hdr;
@@ -375,6 +384,7 @@ typedef union {
     tBTA_JV_API_RFCOMM_CONNECT      rfcomm_connect;
     tBTA_JV_API_RFCOMM_READ         rfcomm_read;
     tBTA_JV_API_RFCOMM_WRITE        rfcomm_write;
+    tBTA_JV_API_RFCOMM_FLOW_CONTROL rfcomm_fc;
     tBTA_JV_API_SET_PM_PROFILE      set_pm;
     tBTA_JV_API_PM_STATE_CHANGE     change_pm_state;
     tBTA_JV_API_RFCOMM_CLOSE        rfcomm_close;
@@ -444,6 +454,7 @@ extern void bta_jv_rfcomm_start_server (tBTA_JV_MSG *p_data);
 extern void bta_jv_rfcomm_stop_server (tBTA_JV_MSG *p_data);
 extern void bta_jv_rfcomm_read (tBTA_JV_MSG *p_data);
 extern void bta_jv_rfcomm_write (tBTA_JV_MSG *p_data);
+extern void bta_jv_rfcomm_flow_control(tBTA_JV_MSG *p_data);
 extern void bta_jv_set_pm_profile (tBTA_JV_MSG *p_data);
 extern void bta_jv_change_pm_state(tBTA_JV_MSG *p_data);
 #if BTA_JV_L2CAP_INCLUDED

components/bt/host/bluedroid/btc/profile/std/spp/btc_spp.c

@@ -101,8 +101,8 @@ static spp_slot_t *spp_malloc_slot(void)
             spp_local_param.spp_slots[i]->connected = FALSE;
             spp_local_param.spp_slots[i]->write_data = NULL;
             spp_local_param.spp_slots[i]->list = list_new(spp_osi_free);
+            spp_local_param.spp_slots[i]->incoming_list = list_new(spp_osi_free);
             if (spp_local_param.spp_mode == ESP_SPP_MODE_VFS) {
-                spp_local_param.spp_slots[i]->incoming_list = list_new(spp_osi_free);
                 if (esp_vfs_register_fd(spp_local_param.spp_vfs_id, &spp_local_param.spp_slots[i]->fd) != ESP_OK) {
                     osi_free(spp_local_param.spp_slots[i]);
                     return NULL;
@@ -165,10 +165,10 @@ static void spp_free_slot(spp_slot_t *slot)
     list_free(slot->list);
     if (spp_local_param.spp_mode == ESP_SPP_MODE_VFS) {
         (void) esp_vfs_unregister_fd(spp_local_param.spp_vfs_id, slot->fd);
-        list_free(slot->incoming_list);
         vRingbufferDelete(slot->ringbuf_read);
         vRingbufferDelete(slot->ringbuf_write);
     }
+    list_free(slot->incoming_list);
     osi_free(slot);
 }
 
@@ -268,7 +268,7 @@ static void *btc_spp_rfcomm_inter_cb(tBTA_JV_EVT event, tBTA_JV *p_data, void *u
         if (slot->connected && p_data->rfc_close.port_status != PORT_LOCAL_CLOSED) {
             BTA_JvRfcommClose(slot->rfc_handle, NULL, (void *)slot->id);
         }
-        spp_free_slot(slot);
+        p_data->rfc_close.slot = slot;
         p_data->rfc_close.status = BTA_JV_SUCCESS;
         break;
     case BTA_JV_RFCOMM_DATA_IND_EVT:
@@ -890,6 +890,7 @@ void btc_spp_cb_handler(btc_msg_t *msg)
         param.close.handle = p_data->rfc_close.handle;
         param.close.async = p_data->rfc_close.async;
         btc_spp_cb_to_app(ESP_SPP_CLOSE_EVT, &param);
+        spp_free_slot((spp_slot_t *)p_data->rfc_close.slot);
         break;
     case BTA_JV_RFCOMM_CONG_EVT:
         if (spp_local_param.spp_mode == ESP_SPP_MODE_CB) {
@@ -921,18 +922,52 @@ void btc_spp_cb_handler(btc_msg_t *msg)
         }
         break;
     case BTA_JV_RFCOMM_DATA_IND_EVT:
-        param.data_ind.status = ESP_SPP_SUCCESS;
+        do {
-        param.data_ind.handle = p_data->data_ind.handle;
+            uint8_t serial;
-        if (p_data->data_ind.p_buf) {
+            BT_HDR *p_buf;
-            param.data_ind.len = p_data->data_ind.p_buf->len;
+            UINT16 count = 0;
-            param.data_ind.data = p_data->data_ind.p_buf->data + p_data->data_ind.p_buf->offset;
-        } else {
-            param.data_ind.len = 0;
-            param.data_ind.data = NULL;
-        }
 
-        btc_spp_cb_to_app(ESP_SPP_DATA_IND_EVT, &param);
+            osi_mutex_lock(&spp_local_param.spp_slot_mutex, OSI_MUTEX_MAX_TIMEOUT);
-        osi_free (p_data->data_ind.p_buf);
+            slot = spp_find_slot_by_handle(p_data->data_ind.handle);
+            if (slot) {
+                serial = slot->serial;
+            }
+            osi_mutex_unlock(&spp_local_param.spp_slot_mutex);
+
+            if (!slot) {
+                BTC_TRACE_ERROR("%s unable to find RFCOMM slot!", __func__);
+                break;
+            }
+
+            while (1) {
+                // get incoming_data from slot incoming list
+                osi_mutex_lock(&spp_local_param.spp_slot_mutex, OSI_MUTEX_MAX_TIMEOUT);
+                if ((slot = spp_local_param.spp_slots[serial]) != NULL && slot->rfc_handle == p_data->data_ind.handle && !list_is_empty(slot->incoming_list)) {
+                    p_buf = list_front(slot->incoming_list);
+                    list_delete(slot->incoming_list, p_buf);
+                } else {
+                    osi_mutex_unlock(&spp_local_param.spp_slot_mutex);
+                    break;
+                }
+                osi_mutex_unlock(&spp_local_param.spp_slot_mutex);
+
+                // invoke callback
+                if (p_buf) {
+                    count += 1;
+                    param.data_ind.status = ESP_SPP_SUCCESS;
+                    param.data_ind.handle = p_data->data_ind.handle;
+                    param.data_ind.len = p_buf->len;
+                    param.data_ind.data = p_buf->data + p_buf->offset;
+                    btc_spp_cb_to_app(ESP_SPP_DATA_IND_EVT, &param);
+                    BTC_TRACE_DEBUG("data cb to app: len %d\n", p_buf->len);
+                    osi_free(p_buf);
+                }
+            }
+            if (count != 0) {
+                BTA_JvRfcommFlowControl(p_data->data_ind.handle, count);
+                BTC_TRACE_DEBUG("%s give credits:%d\n", __func__, count);
+            }
+        } while (0);
         break;
     case BTA_JV_FREE_SCN_EVT:
         if (p_data->free_scn.server_status == BTA_JV_SERVER_RUNNING) {
@@ -957,28 +992,9 @@ void btc_spp_cb_handler(btc_msg_t *msg)
 
 }
 
-/**
- * If there is too much data not accepted, wait until accepted,or discard it when timeout!
- * @param list  list
- * @param p_buf incoming data
- */
-static void spp_delay_append(list_t *list, BT_HDR *p_buf){
-    uint8_t count = 0;
-    while (count++ < 100) {
-        if (list_length(list) < 200){
-            osi_mutex_lock(&spp_local_param.spp_slot_mutex, OSI_MUTEX_MAX_TIMEOUT);
-            list_append(list, p_buf);
-            osi_mutex_unlock(&spp_local_param.spp_slot_mutex);
-            return;
-        }
-        vTaskDelay(100 / portTICK_PERIOD_MS);
-    }
-    osi_free(p_buf);
-    BTC_TRACE_WARNING("%s There is too much data not accepted, discard it!", __func__);
-}
-
 int bta_co_rfc_data_incoming(void *user_data, BT_HDR *p_buf)
 {
+    int ret = 1;
     bt_status_t status;
     tBTA_JV p_data;
     btc_msg_t msg;
@@ -999,36 +1015,35 @@ int bta_co_rfc_data_incoming(void *user_data, BT_HDR *p_buf)
         return -1;
     }
     p_data.data_ind.handle = slot->rfc_handle;
+    p_data.data_ind.p_buf = NULL;
 
     if (spp_local_param.spp_mode == ESP_SPP_MODE_CB) {
-        p_data.data_ind.p_buf = p_buf;
+        bool incoming_list_empty = list_is_empty(slot->incoming_list);
-        status = btc_transfer_context(&msg, &p_data,
+        list_append(slot->incoming_list, p_buf);
-                                      sizeof(tBTA_JV), NULL);
+        if (incoming_list_empty) {
-        if (status != BT_STATUS_SUCCESS) {
+            BTC_TRACE_DEBUG("%s data post! %d, %d", __func__, slot->rfc_handle, list_length(slot->incoming_list));
-            BTC_TRACE_ERROR("%s btc_transfer_context failed\n", __func__);
+            status = btc_transfer_context(&msg, &p_data, sizeof(tBTA_JV), NULL);
+            assert(status == BT_STATUS_SUCCESS);
+        } else if (list_length(slot->incoming_list) > 2) {
+            BTC_TRACE_ERROR("%s data post stop! %d %d", __func__, slot->rfc_handle, list_length(slot->incoming_list));
+            ret = 0;
         }
     } else {
-        if (list_is_empty(slot->incoming_list)) {
+        list_append(slot->incoming_list, p_buf);
-            BaseType_t done = xRingbufferSend(slot->ringbuf_read, p_buf->data + p_buf->offset, p_buf->len, 0);
+        if (list_length(slot->incoming_list) > 2) {
-            if (done) {
+            BTC_TRACE_ERROR("%s data post stop! %d %d", __func__, slot->rfc_handle, list_length(slot->incoming_list));
-                osi_free (p_buf);
+            ret = 0;
-            } else {
-                list_append(slot->incoming_list, p_buf);
-            }
-        } else {
-            list_t *list = slot->incoming_list;
-            osi_mutex_unlock(&spp_local_param.spp_slot_mutex);
-            spp_delay_append(list,p_buf);
-            return 1;
         }
     }
     osi_mutex_unlock(&spp_local_param.spp_slot_mutex);
-    return 1;
+    return ret;
 }
+
 int bta_co_rfc_data_outgoing_size(void *user_data, int *size)
 {
     return 1;
 }
+
 int bta_co_rfc_data_outgoing(void *user_data, uint8_t *buf, uint16_t size)
 {
     return 1;
@@ -1076,20 +1091,6 @@ static int spp_vfs_close(int fd)
     return 0;
 }
 
-static bool incoming_list_2_ringbuf_read(spp_slot_t *slot)
-{
-    while (!list_is_empty(slot->incoming_list)) {
-        BT_HDR *p_buf = list_front(slot->incoming_list);
-        BaseType_t done = xRingbufferSend(slot->ringbuf_read, p_buf->data + p_buf->offset, p_buf->len, 0);
-        if (done) {
-            list_remove(slot->incoming_list, p_buf);
-        } else {
-            return false;
-        }
-    }
-    return true;
-}
-
 static ssize_t spp_vfs_read(int fd, void * dst, size_t size)
 {
     if (!is_spp_init()) {
@@ -1103,12 +1104,28 @@ static ssize_t spp_vfs_read(int fd, void * dst, size_t size)
         osi_mutex_unlock(&spp_local_param.spp_slot_mutex);
         return -1;
     }
-    incoming_list_2_ringbuf_read(slot);
+    ssize_t item_size = 0;
-    size_t item_size = 0;
+    uint16_t count = 0;
-    uint8_t *data = xRingbufferReceiveUpTo(slot->ringbuf_read, &item_size, 0, size);
+    while (!list_is_empty(slot->incoming_list) && size > 0) {
-    if (item_size > 0){
+        BT_HDR *p_buf = list_front(slot->incoming_list);
-        memcpy(dst, data, item_size);
+        if (p_buf->len <= size) {
-        vRingbufferReturnItem(slot->ringbuf_read, data);
+            memcpy(dst, p_buf->data + p_buf->offset, p_buf->len);
+            size -= p_buf->len;
+            item_size += p_buf->len;
+            dst += p_buf->len;
+            list_remove(slot->incoming_list, p_buf);
+            count++;
+        } else {
+            memcpy(dst, p_buf->data + p_buf->offset, size);
+            item_size += size;
+            p_buf->offset += size;
+            p_buf->len -= size;
+            size = 0;
+        }
+    }
+    if (count > 0) {
+        BTA_JvRfcommFlowControl(slot->rfc_handle, count);
+        BTC_TRACE_DEBUG("%s give credits:%d\n", __func__, count);
     }
     osi_mutex_unlock(&spp_local_param.spp_slot_mutex);
     return item_size;

components/bt/host/bluedroid/stack/include/stack/port_api.h

@@ -409,7 +409,18 @@ extern int PORT_Control (UINT16 handle, UINT8 signal);
 *******************************************************************************/
 extern int PORT_FlowControl (UINT16 handle, BOOLEAN enable);
 
-
+/*******************************************************************************
+**
+** Function         PORT_FlowControl_GiveCredit
+**
+** Description      This function gives specified credits to the peer
+**
+** Parameters:      handle        - Handle returned in the RFCOMM_CreateConnection
+**                  enable        - enables data flow
+**                  credits_given - credits to give
+**
+*******************************************************************************/
+extern int PORT_FlowControl_GiveCredit (UINT16 handle, BOOLEAN enable, UINT16 credits_given);
 /*******************************************************************************
 **
 ** Function         PORT_GetModemStatus

components/bt/host/bluedroid/stack/rfcomm/port_api.c

@@ -899,6 +899,77 @@ int PORT_FlowControl_MaxCredit (UINT16 handle, BOOLEAN enable)
 }
 #endif
 
+/*******************************************************************************
+**
+** Function         PORT_FlowControl_GiveCredit
+**
+** Description      This function gives specified credits to the peer
+**
+** Parameters:      handle        - Handle returned in the RFCOMM_CreateConnection
+**                  enable        - enables data flow
+**                  credits_given - credits to give
+**
+*******************************************************************************/
+int PORT_FlowControl_GiveCredit (UINT16 handle, BOOLEAN enable, UINT16 credits_given)
+{
+    tPORT      *p_port;
+    BOOLEAN    old_fc;
+    UINT32     events;
+
+    RFCOMM_TRACE_DEBUG("%s handle:%d enable: %d, cred %d", __func__, handle, enable, credits_given);
+
+    /* Check if handle is valid to avoid crashing */
+    if ((handle == 0) || (handle > MAX_RFC_PORTS)) {
+        return (PORT_BAD_HANDLE);
+    }
+
+    p_port = &rfc_cb.port.port[handle - 1];
+
+    if (!p_port->in_use || (p_port->state == PORT_STATE_CLOSED)) {
+        return (PORT_NOT_OPENED);
+    }
+
+    if (!p_port->rfc.p_mcb) {
+        return (PORT_NOT_OPENED);
+    }
+
+    p_port->rx.user_fc = !enable;
+
+    if (p_port->rfc.p_mcb->flow == PORT_FC_CREDIT) {
+        if (!p_port->rx.user_fc) {
+            port_flow_control_peer(p_port, TRUE, credits_given);
+        }
+    } else {
+        assert(0); // karl: temporarily not allowed
+        old_fc = p_port->local_ctrl.fc;
+
+        /* FC is set if user is set or peer is set */
+        p_port->local_ctrl.fc = (p_port->rx.user_fc | p_port->rx.peer_fc);
+
+        if (p_port->local_ctrl.fc != old_fc) {
+            port_start_control (p_port);
+        }
+    }
+
+    /* Need to take care of the case when we could not deliver events */
+    /* to the application because we were flow controlled */
+    if (enable && (p_port->rx.queue_size != 0)) {
+        assert(0); // karl: temporarily not allowed
+        events = PORT_EV_RXCHAR;
+        if (p_port->rx_flag_ev_pending) {
+            p_port->rx_flag_ev_pending = FALSE;
+            events |= PORT_EV_RXFLAG;
+        }
+
+        events &= p_port->ev_mask;
+        if (p_port->p_callback && events) {
+            p_port->p_callback (events, p_port->inx);
+        }
+    }
+    return (PORT_SUCCESS);
+}
+
+
 /*******************************************************************************
 **
 ** Function         PORT_GetModemStatus

components/bt/host/bluedroid/stack/rfcomm/port_rfc.c

@@ -826,7 +826,8 @@ void PORT_DataInd (tRFC_MCB *p_mcb, UINT8 dlci, BT_HDR *p_buf)
         /* Another packet is delivered to user.  Send credits to peer if required */
 
         if (p_port->p_data_co_callback(p_port->inx, (UINT8 *)p_buf, -1, DATA_CO_CALLBACK_TYPE_INCOMING)) {
-            port_flow_control_peer(p_port, TRUE, 1);
+            // do nothing, flow control credits will be given upon upper-layer request;
+            // port_flow_control_peer(p_port, TRUE, 1);
         } else {
             port_flow_control_peer(p_port, FALSE, 0);
         }

components/bt/host/bluedroid/stack/rfcomm/port_utils.c

@@ -210,17 +210,17 @@ void port_release_port (tPORT *p_port)
 
     osi_mutex_global_lock();
     RFCOMM_TRACE_DEBUG("port_release_port, p_port:%p", p_port);
-    if (p_port->rx.queue) {
+    if (p_port->rx.queue != NULL) {
         while ((p_buf = (BT_HDR *)fixed_queue_dequeue(p_port->rx.queue, 0)) != NULL) {
-            osi_free (p_buf);
+            osi_free(p_buf);
         }
     }
     p_port->rx.queue_size = 0;
 
-    if (p_port->tx.queue) {
+    if (p_port->tx.queue != NULL) {
         while ((p_buf = (BT_HDR *)fixed_queue_dequeue(p_port->tx.queue, 0)) != NULL) {
-            osi_free (p_buf);
+            osi_free(p_buf);
-        }   
+        }
     }
     p_port->tx.queue_size = 0;
 
@@ -514,10 +514,12 @@ void port_flow_control_peer(tPORT *p_port, BOOLEAN enable, UINT16 count)
                     && (p_port->credit_rx_max > p_port->credit_rx)) {
                 rfc_send_credit(p_port->rfc.p_mcb, p_port->dlci,
                                 (UINT8) (p_port->credit_rx_max - p_port->credit_rx));
-
+                RFCOMM_TRACE_DEBUG("send credit: max %d, rx %d, count %d", p_port->credit_rx_max, p_port->credit_rx, count);
                 p_port->credit_rx = p_port->credit_rx_max;
 
                 p_port->rx.peer_fc = FALSE;
+            } else {
+                RFCOMM_TRACE_DEBUG("credit: max %d, rx %d, low %d", p_port->credit_rx_max, p_port->credit_rx, p_port->credit_rx_low);
             }
         }
         /* else want to disable flow from peer */