Report whether other devices are sharing the USB bus.

Author: martinling

host/hackrf-tools/src/hackrf_info.c

@@ -254,6 +254,23 @@ int main(void)
 				hackrf_error_name(result),
 				result);
 		}
+
+		result = hackrf_device_list_bus_sharing(list, i);
+		if (result < 0) {
+			fprintf(stderr,
+				"hackrf_device_list_bus_sharing() failed: %s (%d)\n",
+				hackrf_error_name(result),
+				result);
+		} else if (result == 0) {
+			printf("This device is on its own USB bus.\n");
+		} else if (result == 1) {
+			printf("There is 1 other device on the same USB bus.\n"
+			       "You may have problems at high sample rates.\n");
+		} else {
+			printf("There are %d other devices on the same USB bus.\n"
+			       "You may have problems at high sample rates.\n",
+			       result);
+		}
 	}
 
 	hackrf_device_list_free(list);

host/libhackrf/src/hackrf.c

@@ -860,6 +860,30 @@ int ADDCALL hackrf_device_list_open(
 	return hackrf_open_setup(usb_device, device);
 }
 
+int ADDCALL hackrf_device_list_bus_sharing(hackrf_device_list_t* list, int idx)
+{
+	libusb_device *usb_dev, *hackrf_dev;
+	uint8_t hackrf_bus;
+	int other_device_count = 0;
+	int i;
+	if (list == NULL || list->usb_devices == NULL || list->usb_device_index == NULL ||
+	    idx < 0 || idx > list->devicecount) {
+		return HACKRF_ERROR_INVALID_PARAM;
+	}
+	hackrf_dev = list->usb_devices[list->usb_device_index[idx]];
+	hackrf_bus = libusb_get_bus_number(hackrf_dev);
+	for (i = 0; i < list->usb_devicecount; i++) {
+		usb_dev = (libusb_device*) list->usb_devices[i];
+		// Don't count the HackRF, devices on other buses, or the root hub.
+		if (usb_dev != hackrf_dev &&
+		    libusb_get_bus_number(usb_dev) == hackrf_bus &&
+		    libusb_get_parent(usb_dev) != NULL) {
+			other_device_count++;
+		}
+	}
+	return other_device_count;
+}
+
 int ADDCALL hackrf_set_transceiver_mode(
 	hackrf_device* device,
 	hackrf_transceiver_mode value)

host/libhackrf/src/hackrf.h

@@ -1106,6 +1106,18 @@ extern ADDAPI int ADDCALL hackrf_device_list_open(
 	int idx,
 	hackrf_device** device);
 
+/**
+ * Check if a listed HackRF device is sharing its USB bus with other devices.
+ *
+ * @param[in] list device list to query
+ * @param[in] idx index of the HackRF device in the list
+ * @return The number of devices sharing the USB bus with the specified HackRF, or a negative error code from @ref hackrf_error
+ *
+ */
+extern ADDAPI int ADDCALL hackrf_device_list_bus_sharing(
+	hackrf_device_list_t* list,
+	int idx);
+
 /**
  * Free a previously allocated @ref hackrf_device_list list.
  * @param[in] list list to free