usb: dwc3: gadget: fix set_halt() bug with pending transfers

According to our Gadget Framework API documentation,
->set_halt() *must* return -EAGAIN if we have pending
transfers (on either direction) or FIFO isn't empty (on
TX endpoints).

Fix this bug so that the mass storage gadget can be used
without stall=0 parameter.

This patch should be backported to all kernels since v3.2.

Cc: <stable@vger.kernel.org> # v3.2+
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Felipe Balbi <balbi@ti.com>

3 files changed, 15 insertions, 7 deletions

diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 36f61582b5b5..ae6b5753fe67 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -256,7 +256,7 @@ static void dwc3_ep0_stall_and_restart(struct dwc3 *dwc)
 
         /* stall is always issued on EP0 */
         dep = dwc->eps[0];
-        __dwc3_gadget_ep_set_halt(dep, 1);
+        __dwc3_gadget_ep_set_halt(dep, 1, false);
         dep->flags = DWC3_EP_ENABLED;
         dwc->delayed_status = false;
 
@@ -480,7 +480,7 @@ static int dwc3_ep0_handle_feature(struct dwc3 *dwc,
                                 return -EINVAL;
                         if (set == 0 && (dep->flags & DWC3_EP_WEDGE))
                                 break;
-                        ret = __dwc3_gadget_ep_set_halt(dep, set);
+                        ret = __dwc3_gadget_ep_set_halt(dep, set, true);
                         if (ret)
                                 return -EINVAL;
                         break;
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index b98295efd912..f6d1dbafa298 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -581,7 +581,7 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
 
         /* make sure HW endpoint isn't stalled */
         if (dep->flags & DWC3_EP_STALL)
-                __dwc3_gadget_ep_set_halt(dep, 0);
+                __dwc3_gadget_ep_set_halt(dep, 0, false);
 
         reg = dwc3_readl(dwc->regs, DWC3_DALEPENA);
         reg &= ~DWC3_DALEPENA_EP(dep->number);
@@ -1202,7 +1202,7 @@ out0:
         return ret;
 }
 
-int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value)
+int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol)
 {
         struct dwc3_gadget_ep_cmd_params        params;
         struct dwc3                             *dwc = dep->dwc;
@@ -1216,6 +1216,14 @@ int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value)
         memset(&params, 0x00, sizeof(params));
 
         if (value) {
+                if (!protocol && ((dep->direction && dep->flags & DWC3_EP_BUSY) ||
+                                (!list_empty(&dep->req_queued) ||
+                                 !list_empty(&dep->request_list)))) {
+                        dev_dbg(dwc->dev, "%s: pending request, cannot halt\n",
+                                        dep->name);
+                        return -EAGAIN;
+                }
+
                 ret = dwc3_send_gadget_ep_cmd(dwc, dep->number,
                         DWC3_DEPCMD_SETSTALL, &params);
                 if (ret)
@@ -1246,7 +1254,7 @@ static int dwc3_gadget_ep_set_halt(struct usb_ep *ep, int value)
         int                             ret;
 
         spin_lock_irqsave(&dwc->lock, flags);
-        ret = __dwc3_gadget_ep_set_halt(dep, value);
+        ret = __dwc3_gadget_ep_set_halt(dep, value, false);
         spin_unlock_irqrestore(&dwc->lock, flags);
 
         return ret;
@@ -1265,7 +1273,7 @@ static int dwc3_gadget_ep_set_wedge(struct usb_ep *ep)
         if (dep->number == 0 || dep->number == 1)
                 ret = __dwc3_gadget_ep0_set_halt(ep, 1);
         else
-                ret = __dwc3_gadget_ep_set_halt(dep, 1);
+                ret = __dwc3_gadget_ep_set_halt(dep, 1, false);
         spin_unlock_irqrestore(&dwc->lock, flags);
 
         return ret;
diff --git a/drivers/usb/dwc3/gadget.h b/drivers/usb/dwc3/gadget.h
index f889008faa63..18ae3eaa8b6f 100644
--- a/drivers/usb/dwc3/gadget.h
+++ b/drivers/usb/dwc3/gadget.h
@@ -86,7 +86,7 @@ int __dwc3_gadget_ep0_set_halt(struct usb_ep *ep, int value);
 int dwc3_gadget_ep0_set_halt(struct usb_ep *ep, int value);
 int dwc3_gadget_ep0_queue(struct usb_ep *ep, struct usb_request *request,
                 gfp_t gfp_flags);
-int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value);
+int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol);
 
 /**
  * dwc3_gadget_ep_get_transfer_index - Gets transfer index from HW