From 8038f6d2881d58f5322109a2f5ec2de5aaa6fc30 Mon Sep 17 00:00:00 2001
From: Sam Protsenko <semen.protsenko@linaro.org>
Date: Tue, 16 Feb 2016 19:59:19 +0200
Subject: usb: gadget: composite: Correct recovery path for register

In case when usb_composite_register() failed once (for whatever reason),
it will fail further even if all conditions are correct. Example:

    => fastboot 2
    Invalid Controller Index
    couldn't find an available UDC
    g_dnl_register: failed!, error: -19
    exit not allowed from main input shell.

    => fastboot 0
    g_dnl_register: failed!, error: -22
    exit not allowed from main input shell.

Despite that 0 is correct index for USB controller, "fastboot 0" command
will fail, because "composite" structure wasn't cleared properly on
previous fail (on "fastboot 2" command).

This patch fixes that erroneous behavior, allowing us to use composite
even after previous failure.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 60f9272..d0ee784 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1077,6 +1077,8 @@ static struct usb_gadget_driver composite_driver = {
  */
 int usb_composite_register(struct usb_composite_driver *driver)
 {
+	int res;
+
 	if (!driver || !driver->dev || !driver->bind || composite)
 		return -EINVAL;
 
@@ -1084,7 +1086,11 @@ int usb_composite_register(struct usb_composite_driver *driver)
 		driver->name = "composite";
 	composite = driver;
 
-	return usb_gadget_register_driver(&composite_driver);
+	res = usb_gadget_register_driver(&composite_driver);
+	if (res != 0)
+		composite = NULL;
+
+	return res;
 }
 
 /**
-- 
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