linux-kernel - [PATCH v3 2/2] usb: dwc3: Wait for control tranfer completed when stopping gadget

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Date:   Mon, 19 Sep 2016 19:52:18 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     balbi@...nel.org, gregkh@...uxfoundation.org
Cc:     broonie@...nel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, baolin.wang@...aro.org
Subject: [PATCH v3 2/2] usb: dwc3: Wait for control tranfer completed when stopping gadget

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@...aro.org>
---
 drivers/usb/dwc3/core.h   |    2 ++
 drivers/usb/dwc3/ep0.c    |    2 ++
 drivers/usb/dwc3/gadget.c |   23 +++++++++++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index b2317e7..01a6fbd 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 tranfer 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 ca2ae5b..3a30d51 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1437,6 +1437,15 @@ 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) {
+		reinit_completion(&dwc->ep0_in_setup);
+		return -EBUSY;
+	}
+
 	reg = dwc3_readl(dwc->regs, DWC3_DCTL);
 	if (is_on) {
 		if (dwc->revision <= DWC3_REVISION_187A) {
@@ -1487,10 +1496,22 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 
 	is_on = !!is_on;
 
+try_again:
 	spin_lock_irqsave(&dwc->lock, flags);
 	ret = dwc3_gadget_run_stop(dwc, is_on, false);
 	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 stop gadget.\n");
+			return -ETIMEDOUT;
+		} else {
+			goto try_again;
+		}
+	}
+
 	return ret;
 }
 
@@ -2914,6 +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