diff --git a/DSView/main.cpp b/DSView/main.cpp
index 8485be26..dac39c93 100755
--- a/DSView/main.cpp
+++ b/DSView/main.cpp
@@ -38,6 +38,8 @@
 #include "config.h"
 #include "pv/appcontrol.h"
 
+//#include <libsigrok4DSL/libsigrok.h>
+
 void usage()
 {
 	fprintf(stdout,
@@ -54,6 +56,8 @@ void usage()
 
 int main(int argc, char *argv[])
 {  
+   // sr_test_usb_api();return 0;
+	 
 	int ret = 0; 
 	const char *open_file = NULL;
  
diff --git a/libsigrok4DSL/hardware/DSL/dsl.c b/libsigrok4DSL/hardware/DSL/dsl.c
index 01e2e01c..70c5da81 100755
--- a/libsigrok4DSL/hardware/DSL/dsl.c
+++ b/libsigrok4DSL/hardware/DSL/dsl.c
@@ -1779,6 +1779,7 @@ SR_PRIV int dsl_dev_open(struct sr_dev_driver *di, struct sr_dev_inst *sdi, gboo
     int ret;
     uint8_t hw_info;
     struct ctl_rd_cmd rd_cmd;
+    int fdError = 0;
 
     devc = sdi->priv;
     usb = sdi->conn;
@@ -1799,7 +1800,7 @@ SR_PRIV int dsl_dev_open(struct sr_dev_driver *di, struct sr_dev_inst *sdi, gboo
         sr_err("%s: Unable to open device.", __func__);
         return SR_ERR;
     }
-
+  
     ret = libusb_claim_interface(usb->devhdl, USB_INTERFACE);
     if (ret != 0) {
         switch(ret) {
@@ -1810,13 +1811,27 @@ SR_PRIV int dsl_dev_open(struct sr_dev_driver *di, struct sr_dev_inst *sdi, gboo
         case LIBUSB_ERROR_NO_DEVICE:
             sr_err("%s: Device has been disconnected.", __func__);
             break;
+        case LIBUSB_ERROR_NOT_FOUND:
+            {
+                sr_err("%s: Unable to claim interface, try again: LIBUSB_ERROR_NOT_FOUND.", __func__);
+                ret = libusb_claim_interface(usb->devhdl, USB_INTERFACE);
+                fdError = 1;
+            }
+            break;
         default:
-            sr_err("%s: Unable to claim interface: %s.",
+            sr_err("%s: Unable to claim interface, try again: %s.",
                    __func__, libusb_error_name(ret));
             break;
         }
 
-        return SR_ERR;
+        if (ret != 0 && fdError == 1){
+             sr_err("%s: Unable to claim interface, the second time: %s.",
+                   __func__, libusb_error_name(ret));
+        }
+
+        if (ret != 0){
+            return SR_ERR;
+        } 
     }
 
     rd_cmd.header.dest = DSL_CTL_HW_STATUS;
diff --git a/libsigrok4DSL/hardware/DSL/dslogic.c b/libsigrok4DSL/hardware/DSL/dslogic.c
index 76419965..345f9db9 100755
--- a/libsigrok4DSL/hardware/DSL/dslogic.c
+++ b/libsigrok4DSL/hardware/DSL/dslogic.c
@@ -287,7 +287,9 @@ static GSList *scan(GSList *options)
 
     /* Find all DSLogic compatible devices and upload firmware to them. */
 	devices = NULL;
-    libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
+    int usbnum = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
+    int stdnum = 0;
+
 	for (i = 0; devlist[i]; i++) {
 		if (conn) {
 			usb = NULL;
@@ -314,6 +316,8 @@ static GSList *scan(GSList *options)
             (usb_speed != LIBUSB_SPEED_SUPER))
             continue;
 
+        stdnum++;
+
 		prof = NULL;
         for (j = 0; supported_DSLogic[j].vid; j++) {
             if (des.idVendor == supported_DSLogic[j].vid &&
diff --git a/libsigrok4DSL/hwdriver.c b/libsigrok4DSL/hwdriver.c
index 6af67d91..5be41d3d 100755
--- a/libsigrok4DSL/hwdriver.c
+++ b/libsigrok4DSL/hwdriver.c
@@ -27,6 +27,8 @@
 #include <glib.h>
 #include "config.h" /* Needed for HAVE_LIBUSB_1_0 and others. */
 
+#include "hardware/DSL/dsl.h"
+
 /* Message logging helpers with subsystem-specific prefix string. */
 #define LOG_PREFIX "hwdriver: "
 #define sr_log(l, s, args...) sr_log(l, LOG_PREFIX s, ## args)
@@ -475,3 +477,79 @@ SR_PRIV int sr_source_add(int fd, int events, int timeout,
 }
 
 /** @} */
+
+/*
+test usb device api
+*/
+SR_API void sr_test_usb_api()
+{
+    libusb_context *ctx;
+    struct libusb_device_descriptor des;
+    int usb_speed;
+    int ret;
+    int i;
+    int num_devs;
+    libusb_device **devlist;
+    int stdnum = 0;
+    int j;
+    int bfind = 0;
+    int dlsnum = 0;
+    struct libusb_device_handle *devhandle;
+
+    printf("\n");
+
+    ret = libusb_init(&ctx);
+    if (ret) {
+	printf("unable to initialize libusb: %i\n", ret);
+    return;	 
+   }
+  
+    num_devs = libusb_get_device_list(ctx, &devlist);
+    printf("usb dev num:%d\n", num_devs);
+
+    for (i=0; i<num_devs; i++){
+        libusb_get_device_descriptor(devlist[i], &des);
+
+        usb_speed = libusb_get_device_speed( devlist[i]);
+
+        if ((usb_speed != LIBUSB_SPEED_HIGH) && (usb_speed != LIBUSB_SPEED_SUPER))
+            continue;
+        stdnum++;
+        bfind = 0;
+
+        for (j = 0; supported_DSLogic[j].vid; j++) {
+            if (des.idVendor == supported_DSLogic[j].vid &&
+                des.idProduct == supported_DSLogic[j].pid &&
+                usb_speed == supported_DSLogic[j].usb_speed) {
+                bfind = 1;
+                break;
+			}
+		}
+
+        if (bfind){
+            dlsnum++;
+
+            devhandle = NULL;
+            ret = libusb_open(devlist[i], &devhandle);
+            if (ret){
+                printf("open device error!%s\n", libusb_error_name(ret));
+            }
+            else{
+                //printf("dev open success\n");
+                  ret = libusb_claim_interface(devhandle, USB_INTERFACE);
+                  if (ret){
+                         printf("Unable to claim interface: %s\n", libusb_error_name(ret));
+                  }
+
+                libusb_close(devhandle);
+            }
+        }
+    }
+
+    printf("std usb dev num:%d\n", stdnum);
+    printf("dls dev num:%d\n", dlsnum);
+
+    libusb_free_device_list(devlist, 0);
+
+   libusb_exit(NULL);
+}
diff --git a/libsigrok4DSL/proto.h b/libsigrok4DSL/proto.h
index 88aaec0e..31937370 100755
--- a/libsigrok4DSL/proto.h
+++ b/libsigrok4DSL/proto.h
@@ -82,10 +82,16 @@ SR_API int sr_status_get(const struct sr_dev_inst *sdi, struct sr_status *status
 SR_API struct sr_config *sr_config_new(int key, GVariant *data);
 SR_API void sr_config_free(struct sr_config *src);
 
-/*--- session.c -------------------------------------------------------------*/
+SR_API void sr_test_usb_api();
 
+/*--------------------session.c----------------*/
 typedef void (*sr_datafeed_callback_t)(const struct sr_dev_inst *sdi,
 		const struct sr_datafeed_packet *packet, void *cb_data);
+                
+SR_API void sr_set_export_original_data(int flag);
+SR_API int sr_get_export_original_flag();
+SR_API void sr_set_firmware_resource_dir(const char *dir);
+
 
 /* Session setup */
 SR_API int sr_session_load(const char *filename);
@@ -183,13 +189,5 @@ SR_PRIV uint16_t ds_trigger_get_mask1(uint16_t stage, uint16_t msc, uint16_t lsc
 SR_PRIV uint16_t ds_trigger_get_value1(uint16_t stage, uint16_t msc, uint16_t lsc, gboolean qutr_mode, gboolean half_mode);
 SR_PRIV uint16_t ds_trigger_get_edge1(uint16_t stage, uint16_t msc, uint16_t lsc, gboolean qutr_mode, gboolean half_mode);
 
-/*--------------------session.c----------------*/
-
-SR_API void sr_set_export_original_data(int flag);
-
-SR_API int sr_get_export_original_flag();
-
-SR_API void sr_set_firmware_resource_dir(const char *dir);
-
-
+ 
 #endif
diff --git a/qtpro/DSView.pro.user b/qtpro/DSView.pro.user
index 936f882c..de29711f 100644
--- a/qtpro/DSView.pro.user
+++ b/qtpro/DSView.pro.user
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE QtCreatorProject>
-<!-- Written by QtCreator 4.11.0, 2021-11-29T18:27:06. -->
+<!-- Written by QtCreator 4.11.0, 2021-12-03T14:57:33. -->
 <qtcreator>
  <data>
   <variable>EnvironmentId</variable>