esp_wifi: optimize WiFi TX performance

components/esp32/Kconfig

@@ -1177,6 +1177,19 @@ menu Wi-Fi
             layer can deliver frames faster than WiFi layer can transmit. In these cases, we may run out
             of TX buffers.
 
+    config ESP32_WIFI_CACHE_TX_BUFFER_NUM
+        int "Max number of WiFi cache TX buffers"
+        depends on (ESP32_SPIRAM_SUPPORT || ESP32S2_SPIRAM_SUPPORT)
+        range 16 128
+        default 32
+        help
+            Set the number of WiFi cache TX buffer number.
+
+            For each TX packet from uplayer, such as LWIP etc, WiFi driver needs to allocate a static TX
+            buffer and makes a copy of uplayer packet. If WiFi driver fails to allocate the static TX buffer,
+            it caches the uplayer packets to a dedicated buffer queue, this option is used to configure the
+            size of the cached TX queue.
+
     config ESP32_WIFI_DYNAMIC_TX_BUFFER_NUM
         int "Max number of WiFi dynamic TX buffers"
         depends on ESP32_WIFI_DYNAMIC_TX_BUFFER
@@ -1226,8 +1239,7 @@ menu Wi-Fi
     config ESP32_WIFI_RX_BA_WIN
         int "WiFi AMPDU RX BA window size"
         depends on ESP32_WIFI_AMPDU_RX_ENABLED
-        range 2 32 if !WIFI_LWIP_ALLOCATION_FROM_SPIRAM_FIRST
+        range 2 32
-        range 16 32 if WIFI_LWIP_ALLOCATION_FROM_SPIRAM_FIRST
         default 6 if !WIFI_LWIP_ALLOCATION_FROM_SPIRAM_FIRST
         default 16 if WIFI_LWIP_ALLOCATION_FROM_SPIRAM_FIRST
         help

components/esp32/event_default_handlers.c

@@ -210,6 +210,7 @@ esp_err_t system_event_ap_start_handle_default(system_event_t *event)
     uint8_t ap_mac[6];
 
     WIFI_API_CALL_CHECK("esp_wifi_internal_reg_rxcb", esp_wifi_internal_reg_rxcb(ESP_IF_WIFI_AP, (wifi_rxcb_t)tcpip_adapter_ap_input), ESP_OK);
+    API_CALL_CHECK("esp_wifi_internal_reg_netstack_buf_cb",esp_wifi_internal_reg_netstack_buf_cb(esp_netif_netstack_buf_ref, esp_netif_netstack_buf_free), ESP_OK);
     WIFI_API_CALL_CHECK("esp_wifi_mac_get",  esp_wifi_get_mac(ESP_IF_WIFI_AP, ap_mac), ESP_OK);
 
     tcpip_adapter_get_ip_info(TCPIP_ADAPTER_IF_AP, &ap_ip);
@@ -232,6 +233,7 @@ esp_err_t system_event_sta_start_handle_default(system_event_t *event)
     tcpip_adapter_ip_info_t sta_ip;
     uint8_t sta_mac[6];
 
+    API_CALL_CHECK("esp_wifi_internal_reg_netstack_buf_cb",esp_wifi_internal_reg_netstack_buf_cb(esp_netif_netstack_buf_ref, esp_netif_netstack_buf_free), ESP_OK);
     WIFI_API_CALL_CHECK("esp_wifi_mac_get",  esp_wifi_get_mac(ESP_IF_WIFI_STA, sta_mac), ESP_OK);
     tcpip_adapter_get_ip_info(TCPIP_ADAPTER_IF_STA, &sta_ip);
     tcpip_adapter_sta_start(sta_mac, &sta_ip);

components/esp32/include/esp_wifi.h

@@ -87,6 +87,8 @@ extern "C" {
 #define ESP_ERR_WIFI_POST        (ESP_ERR_WIFI_BASE + 18)  /*!< Failed to post the event to WiFi task */
 #define ESP_ERR_WIFI_INIT_STATE  (ESP_ERR_WIFI_BASE + 19)  /*!< Invalid WiFi state when init/deinit is called */
 #define ESP_ERR_WIFI_STOP_STATE  (ESP_ERR_WIFI_BASE + 20)  /*!< Returned when WiFi is stopping */
+#define ESP_ERR_WIFI_NOT_ASSOC   (ESP_ERR_WIFI_BASE + 21)  /*!< The WiFi connection is not associated */
+#define ESP_ERR_WIFI_TX_DISALLOW (ESP_ERR_WIFI_BASE + 22)  /*!< The WiFi TX is disallowed */
 
 /**
  * @brief WiFi stack configuration parameters passed to esp_wifi_init call.
@@ -100,12 +102,12 @@ typedef struct {
     int                    tx_buf_type;            /**< WiFi TX buffer type */
     int                    static_tx_buf_num;      /**< WiFi static TX buffer number */
     int                    dynamic_tx_buf_num;     /**< WiFi dynamic TX buffer number */
+    int                    cache_tx_buf_num;       /**< WiFi TX cache buffer number */
     int                    csi_enable;             /**< WiFi channel state information enable flag */
     int                    ampdu_rx_enable;        /**< WiFi AMPDU RX feature enable flag */
     int                    ampdu_tx_enable;        /**< WiFi AMPDU TX feature enable flag */
     int                    nvs_enable;             /**< WiFi NVS flash enable flag */
     int                    nano_enable;            /**< Nano option for printf/scan family enable flag */
-    int                    tx_ba_win;              /**< WiFi Block Ack TX window size */
     int                    rx_ba_win;              /**< WiFi Block Ack RX window size */
     int                    wifi_task_core_id;      /**< WiFi Task Core ID */
     int                    beacon_max_len;         /**< WiFi softAP maximum length of the beacon */
@@ -119,6 +121,12 @@ typedef struct {
 #define WIFI_STATIC_TX_BUFFER_NUM 0
 #endif
 
+#if (CONFIG_ESP32_SPIRAM_SUPPORT | CONFIG_ESP32S2_SPIRAM_SUPPORT)
+#define WIFI_CACHE_TX_BUFFER_NUM  CONFIG_ESP32_WIFI_CACHE_TX_BUFFER_NUM
+#else
+#define WIFI_CACHE_TX_BUFFER_NUM  0
+#endif
+
 #ifdef CONFIG_ESP32_WIFI_DYNAMIC_TX_BUFFER_NUM
 #define WIFI_DYNAMIC_TX_BUFFER_NUM CONFIG_ESP32_WIFI_DYNAMIC_TX_BUFFER_NUM
 #else
@@ -159,12 +167,6 @@ extern const wpa_crypto_funcs_t g_wifi_default_wpa_crypto_funcs;
 
 #define WIFI_INIT_CONFIG_MAGIC    0x1F2F3F4F
 
-#ifdef CONFIG_ESP32_WIFI_AMPDU_TX_ENABLED
-#define WIFI_DEFAULT_TX_BA_WIN CONFIG_ESP32_WIFI_TX_BA_WIN
-#else
-#define WIFI_DEFAULT_TX_BA_WIN 0 /* unused if ampdu_tx_enable == false */
-#endif
-
 #ifdef CONFIG_ESP32_WIFI_AMPDU_RX_ENABLED
 #define WIFI_DEFAULT_RX_BA_WIN CONFIG_ESP32_WIFI_RX_BA_WIN
 #else
@@ -189,6 +191,8 @@ extern const wpa_crypto_funcs_t g_wifi_default_wpa_crypto_funcs;
 #define WIFI_MGMT_SBUF_NUM 32
 #endif
 
+#define CONFIG_FEATURE_CACHE_TX_BUF_BIT (1<<1)
+
 #define WIFI_INIT_CONFIG_DEFAULT() { \
     .event_handler = &esp_event_send, \
     .osi_funcs = &g_wifi_osi_funcs, \
@@ -198,12 +202,12 @@ extern const wpa_crypto_funcs_t g_wifi_default_wpa_crypto_funcs;
     .tx_buf_type = CONFIG_ESP32_WIFI_TX_BUFFER_TYPE,\
     .static_tx_buf_num = WIFI_STATIC_TX_BUFFER_NUM,\
     .dynamic_tx_buf_num = WIFI_DYNAMIC_TX_BUFFER_NUM,\
+    .cache_tx_buf_num = WIFI_CACHE_TX_BUFFER_NUM,\
     .csi_enable = WIFI_CSI_ENABLED,\
     .ampdu_rx_enable = WIFI_AMPDU_RX_ENABLED,\
     .ampdu_tx_enable = WIFI_AMPDU_TX_ENABLED,\
     .nvs_enable = WIFI_NVS_ENABLED,\
     .nano_enable = WIFI_NANO_FORMAT_ENABLED,\
-    .tx_ba_win = WIFI_DEFAULT_TX_BA_WIN,\
     .rx_ba_win = WIFI_DEFAULT_RX_BA_WIN,\
     .wifi_task_core_id = WIFI_TASK_CORE_ID,\
     .beacon_max_len = WIFI_SOFTAP_BEACON_MAX_LEN, \

components/esp32/include/esp_wifi_internal.h

@@ -100,15 +100,6 @@ typedef enum {
  */
 esp_err_t esp_wifi_init_internal(const wifi_init_config_t *config);
 
-/**
-  * @brief  get whether the wifi driver is allowed to transmit data or not
-  *
-  * @return
-  *     - true  : upper layer should stop to transmit data to wifi driver
-  *     - false : upper layer can transmit data to wifi driver
-  */
-bool esp_wifi_internal_tx_is_stop(void);
-
 /**
   * @brief  free the rx buffer which allocated by wifi driver
   *
@@ -119,18 +110,77 @@ void esp_wifi_internal_free_rx_buffer(void* buffer);
 /**
   * @brief  transmit the buffer via wifi driver
   *
+  * This API makes a copy of the input buffer and then forwards the buffer
+  * copy to WiFi driver.
   * @param  wifi_interface_t wifi_if : wifi interface id
   * @param  void *buffer : the buffer to be tansmit
   * @param  uint16_t len : the length of buffer
   *
   * @return
-  *    - ERR_OK  : Successfully transmit the buffer to wifi driver
+  *    - ESP_OK  : Successfully transmit the buffer to wifi driver
-  *    - ERR_MEM : Out of memory
+  *    - ESP_ERR_NO_MEM: out of memory
-  *    - ERR_IF : WiFi driver error
+  *    - ESP_ERR_WIFI_ARG: invalid argument
-  *    - ERR_ARG : Invalid argument
+  *    - ESP_ERR_WIFI_IF : WiFi interface is invalid
+  *    - ESP_ERR_WIFI_CONN : WiFi interface is not created, e.g. send the data to STA while WiFi mode is AP mode
+  *    - ESP_ERR_WIFI_NOT_STARTED : WiFi is not started
+  *    - ESP_ERR_WIFI_STATE : WiFi internal state is not ready, e.g. WiFi is not started
+  *    - ESP_ERR_WIFI_NOT_ASSOC : WiFi is not associated
+  *    - ESP_ERR_WIFI_TX_DISALLOW : WiFi TX is disallowed, e.g. WiFi hasn't pass the authentication
+  *    - ESP_ERR_WIFI_POST : caller fails to post event to WiFi task
   */
 int esp_wifi_internal_tx(wifi_interface_t wifi_if, void *buffer, uint16_t len);
 
+/**
+  * @brief     The net stack buffer reference counter callback function
+  *
+  */
+typedef void (*wifi_netstack_buf_ref_cb_t)(void *netstack_buf);
+
+/**
+  * @brief     The net stack buffer free callback function
+  *
+  */
+typedef void (*wifi_netstack_buf_free_cb_t)(void *netstack_buf);
+
+/**
+  * @brief  transmit the buffer by reference via wifi driver
+  *
+  * This API firstly increases the reference counter of the input buffer and
+  * then forwards the buffer to WiFi driver. The WiFi driver will free the buffer
+  * after processing it. Use esp_wifi_internal_tx() if the uplayer buffer doesn't
+  * supports reference counter.
+  * 
+  * @param  wifi_if : wifi interface id
+  * @param  buffer : the buffer to be tansmit
+  * @param  len : the length of buffer
+  * @param  netstack_buf : the netstack buffer related to bufffer
+  *
+  * @return
+  *    - ESP_OK  : Successfully transmit the buffer to wifi driver
+  *    - ESP_ERR_NO_MEM: out of memory
+  *    - ESP_ERR_WIFI_ARG: invalid argument
+  *    - ESP_ERR_WIFI_IF : WiFi interface is invalid
+  *    - ESP_ERR_WIFI_CONN : WiFi interface is not created, e.g. send the data to STA while WiFi mode is AP mode
+  *    - ESP_ERR_WIFI_NOT_STARTED : WiFi is not started
+  *    - ESP_ERR_WIFI_STATE : WiFi internal state is not ready, e.g. WiFi is not started
+  *    - ESP_ERR_WIFI_NOT_ASSOC : WiFi is not associated
+  *    - ESP_ERR_WIFI_TX_DISALLOW : WiFi TX is disallowed, e.g. WiFi hasn't pass the authentication 
+  *    - ESP_ERR_WIFI_POST : caller fails to post event to WiFi task
+  */
+esp_err_t esp_wifi_internal_tx_by_ref(wifi_interface_t ifx, void *buffer, size_t len, void *netstack_buf);
+	
+/**
+  * @brief  register the net stack buffer reference increasing and free callback
+  *
+  * @param  ref : net stack buffer reference callback
+  * @param  free: net stack buffer free callback
+  *
+  * @return
+  *    - ESP_OK  : Successfully transmit the buffer to wifi driver
+  *    - others  : failed to register the callback
+  */
+esp_err_t esp_wifi_internal_reg_netstack_buf_cb(wifi_netstack_buf_ref_cb_t ref, wifi_netstack_buf_free_cb_t free);
+
 /**
   * @brief     The WiFi RX callback function
   *

components/lwip/port/esp32/netif/wlanif.c

@@ -92,6 +92,15 @@ low_level_init(struct netif *netif)
 #endif
 }
 
+static esp_err_t wifi_transmit_wrap(wifi_interface_t wifi_if, void *buffer, size_t len, void *netstack_buf)
+{
+#if (CONFIG_ESP32_SPIRAM_SUPPORT)
+    return esp_wifi_internal_tx_by_ref(wifi_if, buffer, len, netstack_buf);
+#else
+    return esp_wifi_internal_tx(wifi_if, buffer, len);
+#endif
+}
+
 /**
  * This function should do the actual transmission of the packet. The packet is
  * contained in the pbuf that is passed to the function. This pbuf
@@ -112,14 +121,14 @@ low_level_output(struct netif *netif, struct pbuf *p)
 {
   wifi_interface_t wifi_if = tcpip_adapter_get_esp_if(netif);
   struct pbuf *q = p;
-  err_t ret;
+  esp_err_t ret;
 
   if (wifi_if >= ESP_IF_MAX) {
     return ERR_IF;
   }
 
   if(q->next == NULL) {
-    ret = esp_wifi_internal_tx(wifi_if, q->payload, q->len);
+    ret = wifi_transmit_wrap(wifi_if, q->payload, q->len, q);
   } else {
     LWIP_DEBUGF(PBUF_DEBUG, ("low_level_output: pbuf is a list, application may has bug"));
     q = pbuf_alloc(PBUF_RAW_TX, p->tot_len, PBUF_RAM);
@@ -129,11 +138,19 @@ low_level_output(struct netif *netif, struct pbuf *p)
     } else {
       return ERR_MEM;
     }
-    ret = esp_wifi_internal_tx(wifi_if, q->payload, q->len);
+    ret = wifi_transmit_wrap(wifi_if, q->payload, q->len, q);
     pbuf_free(q);
   }
 
-  return ret;
+  if (ret == ESP_OK) {
+    return ERR_OK;
+  } else if (ret == ESP_ERR_NO_MEM) {
+    return ERR_MEM;
+  } else if (ret == ESP_ERR_INVALID_ARG) {
+    return ERR_ARG;
+  } else {
+    return ERR_IF;
+  }
 }
 
 /**

components/tcpip_adapter/include/tcpip_adapter.h

@@ -676,6 +676,22 @@ esp_err_t tcpip_adapter_get_netif(tcpip_adapter_if_t tcpip_if, void ** netif);
  */
 bool tcpip_adapter_is_netif_up(tcpip_adapter_if_t tcpip_if);
 
+/**
+ * @brief increase the reference counter of net stack buffer
+ *
+ * @param[in]  netstack_buf the net stack buffer
+ *
+ */
+void esp_netif_netstack_buf_ref(void *netstack_buf);
+
+/**
+ * @brief free the netstack buffer
+ *
+ * @param[in]  netstack_buf the net stack buffer
+ *
+ */
+void esp_netif_netstack_buf_free(void *netstack_buf);
+
 #ifdef __cplusplus
 }
 #endif

components/tcpip_adapter/tcpip_adapter_lwip.c

@@ -1285,4 +1285,14 @@ bool tcpip_adapter_is_netif_up(tcpip_adapter_if_t tcpip_if)
     }
 }
 
+void esp_netif_netstack_buf_ref(void *pbuf)
+{
+    pbuf_ref(pbuf);
+}
+
+void esp_netif_netstack_buf_free(void *pbuf)
+{
+    pbuf_free(pbuf);
+}
+
 #endif /* CONFIG_TCPIP_LWIP */