usb: dwc3: gadget: don't clear RUN/STOP when it's invalid to do so

When we change the USB function with configfs dynamically, we possibly
met this situation: one core is doing the control transfer, another core
is trying to unregister the USB gadget from userspace, we must wait for
completing this control tranfer, or it will hang the controller to set
the DEVCTRLHLT flag.

[ felipe.balbi@linux.intel.com: several fixes to the patch
	- call complete() before starting following SETUP transfer
	- add a macro for ep0_in_setup's timeout
	- change commit subject slightly
	- break lines at 72 characters (git adds an 8-character tab)
	- avoid changes to dwc3_gadget_run_stop() ]
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/core.h

@@ -37,6 +37,7 @@
 #define DWC3_MSG_MAX	500
 
 /* Global constants */
+#define DWC3_PULL_UP_TIMEOUT	500	/* ms */
 #define DWC3_ZLP_BUF_SIZE	1024	/* size of a superspeed bulk */
 #define DWC3_EP0_BOUNCE_SIZE	512
 #define DWC3_ENDPOINTS_NUM	32
@@ -751,6 +752,7 @@ struct dwc3_scratchpad_array {
  * @ep0_usb_req: dummy req used while handling STD USB requests
  * @ep0_bounce_addr: dma address of ep0_bounce
  * @scratch_addr: dma address of scratchbuf
+ * @ep0_in_setup: one control transfer is completed and enter setup phase
  * @lock: for synchronizing
  * @dev: pointer to our struct device
  * @xhci: pointer to our xHCI child
@@ -848,6 +850,7 @@ struct dwc3 {
 	dma_addr_t		ep0_bounce_addr;
 	dma_addr_t		scratch_addr;
 	struct dwc3_request	ep0_usb_req;
+	struct completion	ep0_in_setup;
 
 	/* device lock */
 	spinlock_t		lock;

drivers/usb/dwc3/ep0.c

@@ -284,6 +284,8 @@ void dwc3_ep0_out_start(struct dwc3 *dwc)
 {
 	int				ret;
 
+	complete(&dwc->ep0_in_setup);
+
 	ret = dwc3_ep0_start_trans(dwc, 0, dwc->ctrl_req_addr, 8,
 			DWC3_TRBCTL_CONTROL_SETUP, false);
 	WARN_ON(ret < 0);

drivers/usb/dwc3/gadget.c

@@ -1550,6 +1550,21 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 
 	is_on = !!is_on;
 
+	/*
+	 * Per databook, when we want to stop the gadget, if a control transfer
+	 * is still in process, complete it and get the core into setup phase.
+	 */
+	if (!is_on && dwc->ep0state != EP0_SETUP_PHASE) {
+		reinit_completion(&dwc->ep0_in_setup);
+
+		ret = wait_for_completion_timeout(&dwc->ep0_in_setup,
+				msecs_to_jiffies(DWC3_PULL_UP_TIMEOUT));
+		if (ret == 0) {
+			dev_err(dwc->dev, "timed out waiting for SETUP phase\n");
+			return -ETIMEDOUT;
+		}
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	ret = dwc3_gadget_run_stop(dwc, is_on, false);
 	spin_unlock_irqrestore(&dwc->lock, flags);
@@ -2945,6 +2960,8 @@ int dwc3_gadget_init(struct dwc3 *dwc)
 		goto err4;
 	}
 
+	init_completion(&dwc->ep0_in_setup);
+
 	dwc->gadget.ops			= &dwc3_gadget_ops;
 	dwc->gadget.speed		= USB_SPEED_UNKNOWN;
 	dwc->gadget.sg_supported	= true;