How to configure 2.4Ghz and 5Hz mode on Hotspot mode?

Hi firefly,
May i know that how we configure Hotspot dual band frequency 2.4Ghz and 5GHz, currently android lollipop doesn’t provide any interface for this changes.

please tell me how to do that, thanks a lot

like this:

diff --git a/system/netd/server/SoftapController.cpp b/system/netd/server/SoftapController.cpp
index f4ece88..5e896fe 100755
--- a/system/netd/server/SoftapController.cpp
+++ b/system/netd/server/SoftapController.cpp
@@ -151,15 +151,16 @@ int SoftapController::setSoftap(int argc, char *argv[]) {
     if (!strcasecmp(argv[4], "hidden"))
         hidden = 1;

-    if (argc >= 5) {
+    channel = AP_CHANNEL_DEFAULT;
+    /*if (argc >= 5) {
         channel = atoi(argv[5]);
         if (channel <= 0)
             channel = AP_CHANNEL_DEFAULT;
-    }
+    }*/

     asprintf(&wbuf, "interface=%s\ndriver=nl80211\nctrl_interface="
             "/data/misc/wifi/hostapd\nssid=%s\nchannel=%d\nieee80211n=1\n"
-            "hw_mode=g\nignore_broadcast_ssid=%d\nwowlan_triggers=any\n",
+            "hw_mode=a\nignore_broadcast_ssid=%d\nwowlan_triggers=any\n",
             argv[2], argv[3], channel, hidden);

     if (argc > 7) {
diff --git a/system/netd/server/SoftapController.h b/system/netd/server/SoftapController.h
index 7063067..1695559 100644
--- a/system/netd/server/SoftapController.h
+++ b/system/netd/server/SoftapController.h
@@ -25,7 +25,7 @@
 #define AP_BSS_STOP_DELAY      500000
 #define AP_SET_CFG_DELAY       500000
 #define AP_DRIVER_START_DELAY  800000
-#define AP_CHANNEL_DEFAULT     6
+#define AP_CHANNEL_DEFAULT     149

 class SoftapController {
 public: