Re: [PATCH v1] usb: dwc3: gadget: wait for End Transfer to complete

[Felipe Balbi <balbi@kernel.org>]

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Hi,

Baolin Wang <baolin.wang@linaro.org> writes:
> Instead of just delaying for 100us, we should
> actually wait for End Transfer Command Complete
> interrupt before moving on. Note that this should
> only be done if we're dealing with one of the core
> revisions that actually require the interrupt before
> moving on.
>
> [ felipe.balbi@linux.intel.com: minor improvements ]
>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>

I made one extra modification to prevent us from checking for
pm_runtime_suspended() twice:

commit 8f48e8d6d3dfe75b5582c8a7b1ee5739a393748c
Author: Baolin Wang <baolin.wang@linaro.org>
Date:   Mon Oct 31 19:38:36 2016 +0800

    usb: dwc3: gadget: wait for End Transfer to complete
    
    Instead of just delaying for 100us, we should
    actually wait for End Transfer Command Complete
    interrupt before moving on. Note that this should
    only be done if we're dealing with one of the core
    revisions that actually require the interrupt before
    moving on.
    
    [ felipe.balbi@linux.intel.com: minor improvements ]
    
    Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
    Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 5fc437021ac7..c2b86856e85d 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -26,6 +26,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/mm.h>
 #include <linux/debugfs.h>
+#include <linux/wait.h>
 
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
@@ -505,6 +506,7 @@ struct dwc3_event_buffer {
  * @endpoint: usb endpoint
  * @pending_list: list of pending requests for this endpoint
  * @started_list: list of started requests on this endpoint
+ * @wait_end_transfer: wait_queue_head_t for waiting on End Transfer complete
  * @lock: spinlock for endpoint request queue traversal
  * @regs: pointer to first endpoint register
  * @trb_pool: array of transaction buffers
@@ -530,6 +532,8 @@ struct dwc3_ep {
 	struct list_head	pending_list;
 	struct list_head	started_list;
 
+	wait_queue_head_t	wait_end_transfer;
+
 	spinlock_t		lock;
 	void __iomem		*regs;
 
@@ -546,6 +550,7 @@ struct dwc3_ep {
 #define DWC3_EP_BUSY		(1 << 4)
 #define DWC3_EP_PENDING_REQUEST	(1 << 5)
 #define DWC3_EP_MISSED_ISOC	(1 << 6)
+#define DWC3_EP_END_TRANSFER_PENDING	(1 << 7)
 
 	/* This last one is specific to EP0 */
 #define DWC3_EP0_DIR_IN		(1 << 31)
@@ -1050,6 +1055,9 @@ struct dwc3_event_depevt {
 #define DEPEVT_TRANSFER_BUS_EXPIRY	2
 
 	u32	parameters:16;
+
+/* For Command Complete Events */
+#define DEPEVT_PARAMETER_CMD(n)	(((n) & (0xf << 8)) >> 8)
 } __packed;
 
 /**
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 3b53a5714df4..d544e7369776 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -593,11 +593,14 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep,
 		dep->comp_desc = comp_desc;
 		dep->type = usb_endpoint_type(desc);
 		dep->flags |= DWC3_EP_ENABLED;
+		dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
 
 		reg = dwc3_readl(dwc->regs, DWC3_DALEPENA);
 		reg |= DWC3_DALEPENA_EP(dep->number);
 		dwc3_writel(dwc->regs, DWC3_DALEPENA, reg);
 
+		init_waitqueue_head(&dep->wait_end_transfer);
+
 		if (usb_endpoint_xfer_control(desc))
 			return 0;
 
@@ -699,7 +702,7 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
 	dep->endpoint.desc = NULL;
 	dep->comp_desc = NULL;
 	dep->type = 0;
-	dep->flags = 0;
+	dep->flags &= DWC3_EP_END_TRANSFER_PENDING;
 
 	return 0;
 }
@@ -1783,9 +1786,6 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 
 static void __dwc3_gadget_stop(struct dwc3 *dwc)
 {
-	if (pm_runtime_suspended(dwc->dev))
-		return;
-
 	dwc3_gadget_disable_irq(dwc);
 	__dwc3_gadget_ep_disable(dwc->eps[0]);
 	__dwc3_gadget_ep_disable(dwc->eps[1]);
@@ -1795,10 +1795,29 @@ static int dwc3_gadget_stop(struct usb_gadget *g)
 {
 	struct dwc3		*dwc = gadget_to_dwc(g);
 	unsigned long		flags;
+	int			epnum;
+
+	if (pm_runtime_suspended(dwc->dev))
+		return 0;
 
 	spin_lock_irqsave(&dwc->lock, flags);
 	__dwc3_gadget_stop(dwc);
 	dwc->gadget_driver	= NULL;
+
+	for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
+		struct dwc3_ep  *dep = dwc->eps[epnum];
+
+		if (!dep)
+			continue;
+
+		if (!(dep->flags & DWC3_EP_END_TRANSFER_PENDING))
+			continue;
+
+		wait_event_lock_irq(dep->wait_end_transfer,
+				    !(dep->flags & DWC3_EP_END_TRANSFER_PENDING),
+				    dwc->lock);
+	}
+
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	free_irq(dwc->irq_gadget, dwc->ev_buf);
@@ -2171,10 +2190,12 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
 {
 	struct dwc3_ep		*dep;
 	u8			epnum = event->endpoint_number;
+	u8			cmd;
 
 	dep = dwc->eps[epnum];
 
-	if (!(dep->flags & DWC3_EP_ENABLED))
+	if (!(dep->flags & DWC3_EP_ENABLED) &&
+	    !(dep->flags & DWC3_EP_END_TRANSFER_PENDING))
 		return;
 
 	if (epnum == 0 || epnum == 1) {
@@ -2215,8 +2236,15 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
 			return;
 		}
 		break;
-	case DWC3_DEPEVT_RXTXFIFOEVT:
 	case DWC3_DEPEVT_EPCMDCMPLT:
+		cmd = DEPEVT_PARAMETER_CMD(event->parameters);
+
+		if (cmd == DWC3_DEPCMD_ENDTRANSFER) {
+			dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
+			wake_up(&dep->wait_end_transfer);
+		}
+		break;
+	case DWC3_DEPEVT_RXTXFIFOEVT:
 		break;
 	}
 }
@@ -2269,7 +2297,8 @@ static void dwc3_stop_active_transfer(struct dwc3 *dwc, u32 epnum, bool force)
 
 	dep = dwc->eps[epnum];
 
-	if (!dep->resource_index)
+	if ((dep->flags & DWC3_EP_END_TRANSFER_PENDING) ||
+	    !dep->resource_index)
 		return;
 
 	/*
@@ -2313,8 +2342,10 @@ static void dwc3_stop_active_transfer(struct dwc3 *dwc, u32 epnum, bool force)
 	dep->resource_index = 0;
 	dep->flags &= ~DWC3_EP_BUSY;
 
-	if (dwc3_is_usb31(dwc) || dwc->revision < DWC3_REVISION_310A)
+	if (dwc3_is_usb31(dwc) || dwc->revision < DWC3_REVISION_310A) {
+		dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
 		udelay(100);
+	}
 }
 
 static void dwc3_clear_stall_all_ep(struct dwc3 *dwc)

-- 
balbi

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