From 9fc0278283118730b4f4261e35a0b4175815126d Mon Sep 17 00:00:00 2001
From: Filzmaier Josef <j.filzmaier@gmx.at>
Date: Thu, 29 Jun 2017 14:31:12 +0200
Subject: [PATCH] Don't reset the configuration if desired config is already
 active (#6)

Fixes issue #5
---
 AUTHORS   | 3 ++-
 device.go | 9 +++++++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/AUTHORS b/AUTHORS
index 6406cf0..c7743c9 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -10,4 +10,5 @@ Pieter Joost van de Sande <pj@born2code.net>
 Ivan Krasin <imkrasin@gmail.com>
 Jirawat I. <nodtem66@gmail.com>
 Thordur Bjornsson <thorduri@secnorth.net>
-Vincent Serpoul <vincent@serpoul.com>
\ No newline at end of file
+Vincent Serpoul <vincent@serpoul.com>
+Josef Filzmaier <josef.filzmaier@gmail.com>
diff --git a/device.go b/device.go
index 853b2a2..3083717 100644
--- a/device.go
+++ b/device.go
@@ -128,8 +128,13 @@ func (d *Device) Config(cfgNum int) (*Config, error) {
 		dev:     d,
 		claimed: make(map[int]bool),
 	}
-	if err := libusb.setConfig(d.handle, uint8(cfgNum)); err != nil {
-		return nil, fmt.Errorf("failed to set active config %d for the device %s: %v", cfgNum, d, err)
+
+	if activeCfgNum, err := d.ActiveConfigNum(); err != nil {
+		return nil, fmt.Errorf("failed to query active config of the device %s: %v", d, err)
+	} else if cfgNum != activeCfgNum {
+		if err := libusb.setConfig(d.handle, uint8(cfgNum)); err != nil {
+			return nil, fmt.Errorf("failed to set active config %d for the device %s: %v", cfgNum, d, err)
+		}
 	}
 	d.mu.Lock()
 	defer d.mu.Unlock()