WiFi信号强度

WiFi Command流程

 

3. wpa_supplicant启动流程

4. WifiService启动流程

5. SIGNAL_POLL调用流程

 eloop_run->..
 wpa_supplicant_ctrl_iface_receive-> //接收并处理来自framework的command
 wpa_supplicant_ctrl_iface_process-> (SIGNAL_POLL)
 wpa_supplicant_signal_poll->
 wpa_drv_signal_poll  (struct wpa_supplicant *wpa_s,struct wpa_signal_info *si)->
 wpa_driver_signal_poll  (void *priv, struct wpa_signal_info *si)->
     wpa_driver_wext_driver_cmd(priv, RSSI_CMD, buf, sizeof(buf))或  //driver_cmd_wext.c
     wpa_driver_wext_driver_cmd(priv, LINKSPEED_CMD, buf, sizeof(buf))->

       struct iwreq iwr;
       iwr.u.data.pointer = buf;
       iwr.u.data.length = buf_len;
       ioctl(drv->ioctl_sock, SIOCSIWPRIV, &iwr);
       在Kernel中对应函数：
       cfg80211_wext_setpriv (wext-compat.c)
       RSSI_CMD:
       cfg80211_wireless_stats (获取当前已连接AP的信号强度等信息)

      对于上面的LINKSPEED_CMD,如果ioctl不成功，则调用ioctl(drv->ioctl_sock, SIOCGIWRATE, &wrq)
      在Kernel中对应函数：
      cfg80211_wext_giwrate (获取当前已连接AP的发送速度)

      //每个AP对应的信息
      struct station_info {
     u32 filled;
     u32 connected_time;
     u32 inactive_time;
     u32 rx_bytes;
     u32 tx_bytes;
     u16 llid;
     u16 plid;
     u8 plink_state;
     s8 signal;  //信号强度
     s8 signal_avg;
     struct rate_info txrate;  //发送速度
     struct rate_info rxrate;
     u32 rx_packets;
     u32 tx_packets;
     u32 tx_retries;
     u32 tx_failed;
     u32 rx_dropped_misc;
     struct sta_bss_parameters bss_param;

     int generation;
     };

在生产时， 默认Wifi是关闭的，如果需要默认打开，可修改wifiservice.java中的如下代码：

 /**
  * Check if Wi-Fi needs to be enabled and start
  * if needed
  *
  * This function is used only at boot time
  */
 public void checkAndStartWifi() {
     mAirplaneModeOn.set(isAirplaneModeOn());
     mPersistWifiState.set(getPersistedWifiState());
     /* Start if Wi-Fi should be enabled or the saved state indicates Wi-Fi was on */
     boolean wifiEnabled = shouldWifiBeEnabled() || testAndClearWifiSavedState();
     Slog.i(TAG, "WifiService starting up with Wi-Fi " +
             (wifiEnabled ? "enabled" : "disabled"));
     setWifiEnabled(wifiEnabled); //强制设置为true

     mWifiWatchdogStateMachine = WifiWatchdogStateMachine.
            makeWifiWatchdogStateMachine(mContext);

 }