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Commit e29e0293 authored by Jack Pham's avatar Jack Pham
Browse files

usb: gadget: android: Add minimum delay between disconnect and connect 



Some controller hardware, such as DWC3, need a minimum delay
between removing and re-applying the pullups in order for the
host to properly detect a soft disconnect and for subsequent
re-enumeration to succeed. Keep track of the last time
android_disable() was called and delay if necessary so that enough
time will have elapsed before calling usb_gadget_connect() from
android_enable().

Change-Id: I43ba441af7c7f1ea2ffe8547df5f004fbf07c823
Signed-off-by: default avatarJack Pham <jackp@codeaurora.org>
parent 42adf5ed

drivers/usb/gadget/android.c

+20 −0
Original line number Diff line number Diff line
@@ -150,6 +150,8 @@ struct android_usb_function_holder { 
*    Used for controlling ADB userspace disable/enable requests.

* @mutex: Internal mutex for protecting device member fields.

* @pdata: Platform data fetched from the kernel device platfrom data.

* @last_disconnect : Time of the last disconnect. Used to enforce minimum

*    delay before next connect.

* @connected: True if got connect notification from the gadget UDC.

*    False if got disconnect notification from the gadget UDC.

* @sw_connected: Equal to 'connected' only after the connect
@@ -186,6 +188,8 @@ struct android_dev { 
	struct mutex mutex;

	struct android_usb_platform_data *pdata;



	ktime_t last_disconnect;



	bool connected;

	bool sw_connected;

	bool suspended;
@@ -460,10 +464,13 @@ static void android_work(struct work_struct *data) 
	}

}



#define MIN_DISCONNECT_DELAY_MS	30



static int android_enable(struct android_dev *dev)

{

	struct usb_composite_dev *cdev = dev->cdev;

	struct android_configuration *conf;

	ktime_t diff;

	int err = 0;



	if (WARN_ON(!dev->disable_depth))
@@ -481,6 +488,17 @@ static int android_enable(struct android_dev *dev) 
				return err;

			}

		}



		/*

		 * Some controllers need a minimum delay between removing and

		 * re-applying the pullups in order for the host to properly

		 * detect a soft disconnect. Check here if enough time has

		 * elapsed since the last disconnect.

		 */

		diff = ktime_sub(ktime_get(), dev->last_disconnect);

		if (ktime_to_ms(diff) < MIN_DISCONNECT_DELAY_MS)

			msleep(MIN_DISCONNECT_DELAY_MS - ktime_to_ms(diff));



		usb_gadget_connect(cdev->gadget);

	}
@@ -494,6 +512,8 @@ static void android_disable(struct android_dev *dev) 


	if (dev->disable_depth++ == 0) {

		usb_gadget_disconnect(cdev->gadget);

		dev->last_disconnect = ktime_get();



		/* Cancel pending control requests */

		usb_ep_dequeue(cdev->gadget->ep0, cdev->req);