usb: dwc3: gadget: start requests as soon as they come

In an attempt to make dwc3 slightly faster, let's
start usb_requests as soon as they come as that will
let us avoid a XFER_NOT_READY event and save a little
bit of time.

Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 0429820..2d0dc2d 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1072,6 +1072,22 @@ static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
        list_add_tail(&req->list, &dep->request_list);
 
        /*
+        * If there are no pending requests and the endpoint isn't already
+        * busy, we will just start the request straight away.
+        *
+        * This will save one IRQ (XFER_NOT_READY) and possibly make it a
+        * little bit faster.
+        */
+       if (!usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
+                       !(dep->flags & DWC3_EP_BUSY)) {
+               ret = __dwc3_gadget_kick_transfer(dep, 0, true);
+               if (ret && ret != -EBUSY)
+                       dev_dbg(dwc->dev, "%s: failed to kick transfers\n",
+                                       dep->name);
+               return ret;
+       }
+
+       /*
         * There are a few special cases:
         *
         * 1. XferNotReady with empty list of requests. We need to kick the