[PATCH v4] usb: dwc3: Wait for control tranfer completed when stopping gadget

[Baolin Wang]

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.

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
---
Changes since v3:
 - Remove the patch 1 which will cause start gadget failed.
 - Remove try_again and refactor the code.

Changes since v2:
 - Move disconnect checking into dwc3_send_gadget_ep_cmd().
 - Rename completion name and issue complete() at one place.
 - Move completion initialization into dwc3_gadget_init().

Changes since v1:
 - Split into 2 separate ptaches.
 - Choose complete mechanism instead of polling.
---
 drivers/usb/dwc3/core.h   |    2 ++
 drivers/usb/dwc3/ep0.c    |    2 ++
 drivers/usb/dwc3/gadget.c |   28 +++++++++++++++++++++++++++-
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index b2317e7..23765a1 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -745,6 +745,7 @@ 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
@@ -843,6 +844,7 @@ 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;
diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index fe79d77..06c167a 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -311,6 +311,8 @@ void dwc3_ep0_out_start(struct dwc3 *dwc)
 	ret = dwc3_ep0_start_trans(dwc, 0, dwc->ctrl_req_addr, 8,
 			DWC3_TRBCTL_CONTROL_SETUP, false);
 	WARN_ON(ret < 0);
+
+	complete(&dwc->ep0_in_setup);
 }
 
 static struct dwc3_ep *dwc3_wIndex_to_dep(struct dwc3 *dwc, __le16 wIndex_le)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 1783406..3722c90 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1434,6 +1434,13 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
 	if (pm_runtime_suspended(dwc->dev))
 		return 0;
 
+	/*
+	 * 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)
+		return -EBUSY;
+
 	reg = dwc3_readl(dwc->regs, DWC3_DCTL);
 	if (is_on) {
 		if (dwc->revision <= DWC3_REVISION_187A) {
@@ -1480,11 +1487,28 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 {
 	struct dwc3		*dwc = gadget_to_dwc(g);
 	unsigned long		flags;
-	int			ret;
+	int			ret = 0;
 
 	is_on = !!is_on;
 
 	spin_lock_irqsave(&dwc->lock, flags);
+	if (!is_on && !pm_runtime_suspended(dwc->dev) &&
+	    dwc->ep0state != EP0_SETUP_PHASE) {
+		reinit_completion(&dwc->ep0_in_setup);
+		ret = -EBUSY;
+	}
+	spin_unlock_irqrestore(&dwc->lock, flags);
+
+	if (ret == -EBUSY) {
+		ret = wait_for_completion_timeout(&dwc->ep0_in_setup,
+						  msecs_to_jiffies(500));
+		if (ret == 0) {
+			dev_err(dwc->dev, "timeout to wait 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);
 
@@ -2911,6 +2935,8 @@ 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;
-- 
1.7.9.5