usb: dwc3: gadget: Fix ISO transfer performance

Commit 08a36b543803 ("usb: dwc3: gadget: simplify __dwc3_gadget_ep_queue()")
caused a small change in the way ISO transfer is handled in the case
when XferInProgress event happens on Isoc EP with an active transfer.
This caused a performance degradation of 50%. e.g. using g_webcam on DUT
and luvcview on host the video frame rate dropped from 16fps to 8fps
@high-speed.

Make the ISO transfer handling equivalent to that prior to that commit
to get back the original ISO performance numbers.

Fixes: 08a36b543803 ("usb: dwc3: gadget: simplify __dwc3_gadget_ep_queue()")
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 6f6f0b3..3d61808 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1261,14 +1261,24 @@ static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
                                __dwc3_gadget_start_isoc(dwc, dep, cur_uf);
                                dep->flags &= ~DWC3_EP_PENDING_REQUEST;
                        }
+                       return 0;
                }
-               return 0;
+
+               if ((dep->flags & DWC3_EP_BUSY) &&
+                   !(dep->flags & DWC3_EP_MISSED_ISOC)) {
+                       WARN_ON_ONCE(!dep->resource_index);
+                       ret = __dwc3_gadget_kick_transfer(dep,
+                                                         dep->resource_index);
+               }
+
+               goto out;
        }
 
        if (!dwc3_calc_trbs_left(dep))
                return 0;
 
        ret = __dwc3_gadget_kick_transfer(dep, 0);
+out:
        if (ret == -EBUSY)
                ret = 0;