diff --git a/code/application/source/sf_app/code/source/app/sf_service.c b/code/application/source/sf_app/code/source/app/sf_service.c
index 7fd85af55..2832ebe49 100755
--- a/code/application/source/sf_app/code/source/app/sf_service.c
+++ b/code/application/source/sf_app/code/source/app/sf_service.c
@@ -97,9 +97,8 @@ SINT32 app_ttyusb_IsOpen(void) {
     int retryTime = 0;
     int retryFlag = 0;
     static SINT32 s32ret = SF_SUCCESS;
-    static int flag = 0;
 
-    if((flag) && (sf_get_ttyusb_flag()))
+    if(sf_get_ttyusb_flag() >= 0)
     {
         return s32ret;
     }
@@ -142,14 +141,25 @@ SINT32 app_ttyusb_IsOpen(void) {
             break;
         }
     }
-    flag = 1;
+
     MLOGD("e\n");
     return s32ret;
 }
 
 SINT32 sf_ttyusb_restart(void) 
 {
-  SINT32 ret = 0;
+    SINT32 ret = -1;
+    UIMenuStoreInfo *puiPara = sf_app_ui_para_get();
+
+    if(strncmp(puiPara->ModuleVer, GPRS_MODULE_TYPE_EG915Q, 6) == 0)
+    {
+        //eg915q
+    }
+    else
+    {
+        system("killall quectel-CM-EG91");
+    }
+
   ret = sf_hal_ttyusb2_deinit();
   if (ret != 0) 
   {
diff --git a/code/application/source/sf_app/code/source/ttyusb/sf_hal_ttyusb.c b/code/application/source/sf_app/code/source/ttyusb/sf_hal_ttyusb.c
index 744a6dd10..44714cea7 100755
--- a/code/application/source/sf_app/code/source/ttyusb/sf_hal_ttyusb.c
+++ b/code/application/source/sf_app/code/source/ttyusb/sf_hal_ttyusb.c
@@ -209,7 +209,13 @@ static SINT32 hal_ttyusb_config(SINT32 fd, SF_SERIAL_DATA_FRAME_TYPE_S *pSerialA
 static SINT32 hal_ttyusb_write(SINT32 fd, SF_CHAR *sendBuf, SINT32 dataLen)
 {
     SINT32 len = 0;
-	
+
+    if(fd < 0)
+    {
+        MLOGE(" fd write fail!\n");
+        return SF_FAILURE;
+    }
+
     len = write(fd,sendBuf,dataLen);
     if (len == dataLen )
 	{
@@ -252,6 +258,11 @@ static SINT32 hal_ttyusb_read(SINT32 fd, SF_CHAR *recvBuf, SINT32 waitTime)
 	//if(waitTime > 0)
 	//	sf_sleep_ms(waitTime);
 	
+    if(fd < 0)
+    {
+        MLOGE(" fd read fail!\n");
+        return SF_FAILURE;
+    }
 	//while(waitTime--)
     {
 		
@@ -304,7 +315,7 @@ static SINT32 hal_ttyusb_create(SF_CHAR *ttyusbName,SF_SERIAL_DATA_FRAME_TYPE_S
 		usleep(100000);//100ms
 	}
 	
-	if(*pttyfd <= 0)
+	if(*pttyfd == -1)
 		return SF_FAILURE;
 	
 	ret = hal_ttyusb_config(*pttyfd,pSerialAttr);
@@ -318,7 +329,7 @@ static SINT32 hal_ttyusb_create(SF_CHAR *ttyusbName,SF_SERIAL_DATA_FRAME_TYPE_S
 }
 static SINT32 hal_ttyusb_destory(SINT32 fd)
 {
-	int ret = 0;
+	int ret = -1;
 	int count = 0;
 	
 	while ((ret = close(fd)) < 0)
@@ -366,7 +377,7 @@ SINT32 sf_hal_ttyusb2_read(SF_CHAR *recvBuf, SINT32 waitMs)
 }
 SINT32 sf_hal_ttyusb2_deinit(void)
 {
-    SINT32 ret = 0;
+    SINT32 ret = -1;
 
 	if(TtyUSB2Fd < 0)
 	{