ltunify: suggest loading hid-logitech-dj

ltunify.c

@@ -921,6 +921,10 @@ int open_hidraw(void) {
 				"for %s\n", hiddev_name);
 		} else {
 			fprintf(stderr, "No Logitech Unifying Receiver device found\n");
+			if (access("/sys/module/hid_logitech_dj", F_OK)) {
+				fprintf(stderr, "Driver is not loaded, try:"
+						"   sudo modprobe hid-logitech-dj\n");
+			}
 		}
 	}
 	globfree(&matches);