X-Git-Url: https://git.ao2.it/libam7xxx.git/blobdiff_plain/cd64a0277a5ca41122a343b26e4bad98b0377256..9afe9f1293358f92483fba4c7052517e29f831aa:/src/am7xxx.c

diff --git a/src/am7xxx.c b/src/am7xxx.c
index f4203e3..2ba9561 100644
--- a/src/am7xxx.c
+++ b/src/am7xxx.c
@@ -734,8 +734,24 @@ static int open_device(am7xxx_context *ctx,
 	 */
 
 	current_configuration = -1;
-	libusb_get_configuration((*dev)->usb_device, &current_configuration);
+	ret = libusb_get_configuration((*dev)->usb_device,
+				       &current_configuration);
+	if (ret < 0) {
+		debug(ctx, "libusb_get_configuration failed: %s\n",
+		      libusb_error_name(ret));
+		goto out_libusb_close;
+	}
+
 	if (current_configuration != (*dev)->desc->configuration) {
+		/*
+		 * In principle kernel drivers bound to each interface should
+		 * be detached before setting the configuration, but in
+		 * practice this is not necessary for most devices.
+		 *
+		 * For example something like the following function would be
+		 * called:
+		 * 	libusb_detach_all_kernel_drivers((*dev)->usb_device);
+		 */
 		ret = libusb_set_configuration((*dev)->usb_device,
 					       (*dev)->desc->configuration);
 		if (ret < 0) {
@@ -763,16 +779,26 @@ static int open_device(am7xxx_context *ctx,
 	 * http://libusb.sourceforge.net/api-1.0/caveats.html
 	 */
 	current_configuration = -1;
-	libusb_get_configuration((*dev)->usb_device, &current_configuration);
+	ret = libusb_get_configuration((*dev)->usb_device,
+				       &current_configuration);
+	if (ret < 0) {
+		debug(ctx, "libusb_get_configuration after claim failed: %s\n",
+		      libusb_error_name(ret));
+		goto out_libusb_release_interface;
+	}
+
 	if (current_configuration != (*dev)->desc->configuration) {
-		debug(ctx, "libusb configuration changed\n");
-		debug(ctx, "Cannot claim interface %hhu\n",
-		      (*dev)->desc->interface_number);
-		goto out_libusb_close;
+		debug(ctx, "libusb configuration changed (expected: %hhu, current: %hhu\n",
+		      (*dev)->desc->configuration, current_configuration);
+		ret = -EINVAL;
+		goto out_libusb_release_interface;
 	}
 out:
 	return ret;
 
+out_libusb_release_interface:
+	libusb_release_interface((*dev)->usb_device,
+				 (*dev)->desc->interface_number);
 out_libusb_close:
 	libusb_close((*dev)->usb_device);
 	(*dev)->usb_device = NULL;