libusb: add debug message on adapter not found due to wrong serial

When few adapters of the same type are in use, the serial string is
the way to select the right one.
Currently a serial string that does not match any of the connected
adapters will just fail the open, without specific information to
track the issue.

Add a specific message to highlight that the open failure is caused
by a serial mismatch.

Change-Id: I5cb77f1045cc746e532d395b2e5ced40a23ab638
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4701


Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

src/jtag/drivers/libusb0_common.c

@@ -68,6 +68,7 @@ int jtag_libusb_open(const uint16_t vids[], const uint16_t pids[],
 		struct jtag_libusb_device_handle **out)
 {
 	int retval = ERROR_FAIL;
+	bool serial_mismatch = false;
 	struct jtag_libusb_device_handle *libusb_handle;
 	usb_init();
 
@@ -90,14 +91,20 @@ int jtag_libusb_open(const uint16_t vids[], const uint16_t pids[],
 			/* Device must be open to use libusb_get_string_descriptor_ascii. */
 			if (serial != NULL &&
 					!string_descriptor_equal(libusb_handle, dev->descriptor.iSerialNumber, serial)) {
+				serial_mismatch = true;
 				usb_close(libusb_handle);
 				continue;
 			}
 			*out = libusb_handle;
 			retval = ERROR_OK;
+			serial_mismatch = false;
 			break;
 		}
 	}
+
+	if (serial_mismatch)
+		LOG_INFO("No device matches the serial string");
+
 	return retval;
 }
 

src/jtag/drivers/libusb1_common.c

@@ -72,6 +72,7 @@ int jtag_libusb_open(const uint16_t vids[], const uint16_t pids[],
 {
 	int cnt, idx, errCode;
 	int retval = ERROR_FAIL;
+	bool serial_mismatch = false;
 	struct jtag_libusb_device_handle *libusb_handle = NULL;
 
 	if (libusb_init(&jtag_libusb_context) < 0)
@@ -99,6 +100,7 @@ int jtag_libusb_open(const uint16_t vids[], const uint16_t pids[],
 		/* Device must be open to use libusb_get_string_descriptor_ascii. */
 		if (serial != NULL &&
 				!string_descriptor_equal(libusb_handle, dev_desc.iSerialNumber, serial)) {
+			serial_mismatch = true;
 			libusb_close(libusb_handle);
 			continue;
 		}
@@ -106,10 +108,15 @@ int jtag_libusb_open(const uint16_t vids[], const uint16_t pids[],
 		/* Success. */
 		*out = libusb_handle;
 		retval = ERROR_OK;
+		serial_mismatch = false;
 		break;
 	}
 	if (cnt >= 0)
 		libusb_free_device_list(devs, 1);
+
+	if (serial_mismatch)
+		LOG_INFO("No device matches the serial string");
+
 	return retval;
 }