usb: dwc2: gadget: Fix GOUTNAK flow for Slave mode.

Because of dwc2_hsotg_ep_stop_xfr() function uses poll
mode, first need to mask GINTSTS_GOUTNAKEFF interrupt.
In Slave mode GINTSTS_GOUTNAKEFF interrupt will be
aserted only after pop OUT NAK status packet from RxFIFO.

In dwc2_hsotg_ep_sethalt() function before setting
DCTL_SGOUTNAK need to unmask GOUTNAKEFF interrupt.

Tested by USBCV CH9 and MSC tests set in Slave, BDMA and DDMA.
All tests are passed.

Fixes: a4f82771 ("usb: dwc2: gadget: Disable enabled HW endpoint in dwc2_hsotg_ep_disable")
Fixes: 6070636c ("usb: dwc2: Fix Stalling a Non-Isochronous OUT EP")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Link: https://lore.kernel.org/r/e17fad802bbcaf879e1ed6745030993abb93baf8.1626152924.git.Minas.Harutyunyan@synopsys.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc2/gadget.c

@@ -3900,9 +3900,27 @@ static void dwc2_hsotg_ep_stop_xfr(struct dwc2_hsotg *hsotg,
 					 __func__);
 		}
 	} else {
+		/* Mask GINTSTS_GOUTNAKEFF interrupt */
+		dwc2_hsotg_disable_gsint(hsotg, GINTSTS_GOUTNAKEFF);
+
 		if (!(dwc2_readl(hsotg, GINTSTS) & GINTSTS_GOUTNAKEFF))
 			dwc2_set_bit(hsotg, DCTL, DCTL_SGOUTNAK);
 
+		if (!using_dma(hsotg)) {
+			/* Wait for GINTSTS_RXFLVL interrupt */
+			if (dwc2_hsotg_wait_bit_set(hsotg, GINTSTS,
+						    GINTSTS_RXFLVL, 100)) {
+				dev_warn(hsotg->dev, "%s: timeout GINTSTS.RXFLVL\n",
+					 __func__);
+			} else {
+				/*
+				 * Pop GLOBAL OUT NAK status packet from RxFIFO
+				 * to assert GOUTNAKEFF interrupt
+				 */
+				dwc2_readl(hsotg, GRXSTSP);
+			}
+		}
+
 		/* Wait for global nak to take effect */
 		if (dwc2_hsotg_wait_bit_set(hsotg, GINTSTS,
 					    GINTSTS_GOUTNAKEFF, 100))
@@ -4348,6 +4366,9 @@ static int dwc2_hsotg_ep_sethalt(struct usb_ep *ep, int value, bool now)
 		epctl = dwc2_readl(hs, epreg);
 
 		if (value) {
+			/* Unmask GOUTNAKEFF interrupt */
+			dwc2_hsotg_en_gsint(hs, GINTSTS_GOUTNAKEFF);
+
 			if (!(dwc2_readl(hs, GINTSTS) & GINTSTS_GOUTNAKEFF))
 				dwc2_set_bit(hs, DCTL, DCTL_SGOUTNAK);
 			// STALL bit will be set in GOUTNAKEFF interrupt handler