usb: gadget: f_accessory: Fix for UsbAccessory clean unbind.

Reapplying fix by Darren Whobrey (Change 69674)

Fixes issues: 20545, 59667 and 61390.
With prior version of f_accessory.c, UsbAccessories would not
unbind cleanly when application is closed or i/o stopped
while the usb cable is still connected. The accessory gadget
driver would be left in an invalid state which was not reset
on subsequent binding or opening. A reboot was necessary to clear.

In some phones this issues causes the phone to reboot upon
unplugging the USB cable.

Main problem was that acc_disconnect was being called on I/O error
which reset disconnected and online.

Minor fix required to properly track setting and unsetting of
disconnected and online flags. Also added urb Q wakeup's on unbind
to help unblock waiting threads.

Tested on Nexus 7 grouper. Expected behaviour now observed:
closing accessory causes blocked i/o to interrupt with IOException.
Accessory can be restarted following closing of file handle
and re-opening.

This is a generic fix that applies to all devices.

Change-Id: I4e08b326730dd3a2820c863124cee10f7cb5501e
Signed-off-by: Darren Whobrey <d.whobrey@mildai.org>
Signed-off-by: Anson Jacob <ansonjacob.aj@gmail.com>

1 files changed, 17 insertions, 5 deletions

diff --git a/drivers/usb/gadget/function/f_accessory.c b/drivers/usb/gadget/function/f_accessory.c
index f2fa0c271d70..76b8ae08a551 100644
--- a/drivers/usb/gadget/function/f_accessory.c
+++ b/drivers/usb/gadget/function/f_accessory.c
@@ -77,9 +77,13 @@ struct acc_dev {
 	struct usb_ep *ep_in;
 	struct usb_ep *ep_out;
 
-	/* set to 1 when we connect */
+	/* online indicates state of function_set_alt & function_unbind
+	 * set to 1 when we connect
+	 */
 	int online:1;
-	/* Set to 1 when we disconnect.
+
+	/* disconnected indicates state of open & release
+	 * Set to 1 when we disconnect.
 	 * Not cleared until our file is closed.
 	 */
 	int disconnected:1;
@@ -263,7 +267,6 @@ static struct usb_request *req_get(struct acc_dev *dev, struct list_head *head)
 
 static void acc_set_disconnected(struct acc_dev *dev)
 {
-	dev->online = 0;
 	dev->disconnected = 1;
 }
 
@@ -764,7 +767,10 @@ static int acc_release(struct inode *ip, struct file *fp)
 	printk(KERN_INFO "acc_release\n");
 
 	WARN_ON(!atomic_xchg(&_acc_dev->open_excl, 0));
-	_acc_dev->disconnected = 0;
+	/* indicate that we are disconnected
+	 * still could be online so don't touch online flag
+	 */
+	_acc_dev->disconnected = 1;
 	return 0;
 }
 
@@ -1012,6 +1018,10 @@ acc_function_unbind(struct usb_configuration *c, struct usb_function *f)
 	struct usb_request *req;
 	int i;
 
+	dev->online = 0;		/* clear online flag */
+	wake_up(&dev->read_wq);		/* unblock reads on closure */
+	wake_up(&dev->write_wq);	/* likewise for writes */
+
 	while ((req = req_get(dev, &dev->tx_idle)))
 		acc_request_free(req, dev->ep_in);
 	for (i = 0; i < RX_REQ_MAX; i++)
@@ -1143,6 +1153,7 @@ static int acc_function_set_alt(struct usb_function *f,
 	}
 
 	dev->online = 1;
+	dev->disconnected = 0; /* if online then not disconnected */
 
 	/* readers may be blocked waiting for us to go online */
 	wake_up(&dev->read_wq);
@@ -1155,7 +1166,8 @@ static void acc_function_disable(struct usb_function *f)
 	struct usb_composite_dev	*cdev = dev->cdev;
 
 	DBG(cdev, "acc_function_disable\n");
-	acc_set_disconnected(dev);
+	acc_set_disconnected(dev); /* this now only sets disconnected */
+	dev->online = 0; /* so now need to clear online flag here too */
 	usb_ep_disable(dev->ep_in);
 	usb_ep_disable(dev->ep_out);