usb: dwc3: Add ENDXFER command polling

ENDXFER polling is available on version 3.10a and later of the
DWC_usb3 (USB 3.0) controller. With this feature, the software can poll
the CMDACT bit in the DEPCMD register after issuing an ENDXFER command.
This feature is enabled by writing GUCTL2[14].

This feature is NOT available on the DWC_usb31 (USB 3.1) IP.

Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 25e424e..d6d3fa0 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -704,6 +704,17 @@
 		break;
 	}
 
+	/*
+	 * ENDXFER polling is available on version 3.10a and later of
+	 * the DWC_usb3 controller. It is NOT available in the
+	 * DWC_usb31 controller.
+	 */
+	if (!dwc3_is_usb31(dwc) && dwc->revision >= DWC3_REVISION_310A) {
+		reg = dwc3_readl(dwc->regs, DWC3_GUCTL2);
+		reg |= DWC3_GUCTL2_RST_ACTBITLATER;
+		dwc3_writel(dwc->regs, DWC3_GUCTL2, reg);
+	}
+
 	return 0;
 
 err4: