usb: dwc2: gadget: parity fix in isochronous mode

USB OTG driver in isochronous mode has to set the parity of the receiving
microframe. The parity is set to even by default. This causes problems for
an audio gadget, if the host starts transmitting on odd microframes.

This fix uses Incomplete Periodic Transfer interrupt to toggle between
even and odd parity until the Transfer Complete interrupt is received.

Signed-off-by: Roman Bacik <rbacik@broadcom.com>
Reviewed-by: Abhinav Ratna <aratna@broadcom.com>
Reviewed-by: Srinath Mannam <srinath.mannam@broadcom.com>
Signed-off-by: Scott Branden <sbranden@broadcom.com>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc2/core.h

@@ -166,6 +166,7 @@ struct dwc2_hsotg_ep {
 	unsigned int            periodic:1;
 	unsigned int            isochronous:1;
 	unsigned int            send_zlp:1;
+	unsigned int            has_correct_parity:1;
 
 	char                    name[10];
 };

drivers/usb/dwc2/gadget.c

@@ -1513,6 +1513,19 @@ static void dwc2_hsotg_ep0_zlp(struct dwc2_hsotg *hsotg, bool dir_in)
 	dwc2_hsotg_program_zlp(hsotg, hsotg->eps_out[0]);
 }
 
+static void dwc2_hsotg_change_ep_iso_parity(struct dwc2_hsotg *hsotg,
+			u32 epctl_reg)
+{
+	u32 ctrl;
+
+	ctrl = dwc2_readl(hsotg->regs + epctl_reg);
+	if (ctrl & DXEPCTL_EOFRNUM)
+		ctrl |= DXEPCTL_SETEVENFR;
+	else
+		ctrl |= DXEPCTL_SETODDFR;
+	dwc2_writel(ctrl, hsotg->regs + epctl_reg);
+}
+
 /**
  * dwc2_hsotg_handle_outdone - handle receiving OutDone/SetupDone from RXFIFO
  * @hsotg: The device instance
@@ -1583,6 +1596,16 @@ static void dwc2_hsotg_handle_outdone(struct dwc2_hsotg *hsotg, int epnum)
 		return;
 	}
 
+	/*
+	 * Slave mode OUT transfers do not go through XferComplete so
+	 * adjust the ISOC parity here.
+	 */
+	if (!using_dma(hsotg)) {
+		hs_ep->has_correct_parity = 1;
+		if (hs_ep->isochronous && hs_ep->interval == 1)
+			dwc2_hsotg_change_ep_iso_parity(hsotg, DOEPCTL(epnum));
+	}
+
 	dwc2_hsotg_complete_request(hsotg, hs_ep, hs_req, result);
 }
 
@@ -1955,13 +1978,9 @@ static void dwc2_hsotg_epint(struct dwc2_hsotg *hsotg, unsigned int idx,
 		ints &= ~DXEPINT_XFERCOMPL;
 
 	if (ints & DXEPINT_XFERCOMPL) {
-		if (hs_ep->isochronous && hs_ep->interval == 1) {
-			if (ctrl & DXEPCTL_EOFRNUM)
-				ctrl |= DXEPCTL_SETEVENFR;
-			else
-				ctrl |= DXEPCTL_SETODDFR;
-			dwc2_writel(ctrl, hsotg->regs + epctl_reg);
-		}
+		hs_ep->has_correct_parity = 1;
+		if (hs_ep->isochronous && hs_ep->interval == 1)
+			dwc2_hsotg_change_ep_iso_parity(hsotg, epctl_reg);
 
 		dev_dbg(hsotg->dev,
 			"%s: XferCompl: DxEPCTL=0x%08x, DXEPTSIZ=%08x\n",
@@ -2321,7 +2340,8 @@ void dwc2_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,
 		GINTSTS_GOUTNAKEFF | GINTSTS_GINNAKEFF |
 		GINTSTS_USBRST | GINTSTS_RESETDET |
 		GINTSTS_ENUMDONE | GINTSTS_OTGINT |
-		GINTSTS_USBSUSP | GINTSTS_WKUPINT;
+		GINTSTS_USBSUSP | GINTSTS_WKUPINT |
+		GINTSTS_INCOMPL_SOIN | GINTSTS_INCOMPL_SOOUT;
 
 	if (hsotg->core_params->external_id_pin_ctl <= 0)
 		intmsk |= GINTSTS_CONIDSTSCHNG;
@@ -2582,6 +2602,40 @@ irq_retry:
 		dwc2_hsotg_dump(hsotg);
 	}
 
+	if (gintsts & GINTSTS_INCOMPL_SOIN) {
+		u32 idx, epctl_reg;
+		struct dwc2_hsotg_ep *hs_ep;
+
+		dev_dbg(hsotg->dev, "%s: GINTSTS_INCOMPL_SOIN\n", __func__);
+		for (idx = 1; idx < hsotg->num_of_eps; idx++) {
+			hs_ep = hsotg->eps_in[idx];
+
+			if (!hs_ep->isochronous || hs_ep->has_correct_parity)
+				continue;
+
+			epctl_reg = DIEPCTL(idx);
+			dwc2_hsotg_change_ep_iso_parity(hsotg, epctl_reg);
+		}
+		dwc2_writel(GINTSTS_INCOMPL_SOIN, hsotg->regs + GINTSTS);
+	}
+
+	if (gintsts & GINTSTS_INCOMPL_SOOUT) {
+		u32 idx, epctl_reg;
+		struct dwc2_hsotg_ep *hs_ep;
+
+		dev_dbg(hsotg->dev, "%s: GINTSTS_INCOMPL_SOOUT\n", __func__);
+		for (idx = 1; idx < hsotg->num_of_eps; idx++) {
+			hs_ep = hsotg->eps_out[idx];
+
+			if (!hs_ep->isochronous || hs_ep->has_correct_parity)
+				continue;
+
+			epctl_reg = DOEPCTL(idx);
+			dwc2_hsotg_change_ep_iso_parity(hsotg, epctl_reg);
+		}
+		dwc2_writel(GINTSTS_INCOMPL_SOOUT, hsotg->regs + GINTSTS);
+	}
+
 	/*
 	 * if we've had fifo events, we should try and go around the
 	 * loop again to see if there's any point in returning yet.
@@ -2668,6 +2722,7 @@ static int dwc2_hsotg_ep_enable(struct usb_ep *ep,
 	hs_ep->periodic = 0;
 	hs_ep->halted = 0;
 	hs_ep->interval = desc->bInterval;
+	hs_ep->has_correct_parity = 0;
 
 	if (hs_ep->interval > 1 && hs_ep->mc > 1)
 		dev_err(hsotg->dev, "MC > 1 when interval is not 1\n");

drivers/usb/dwc2/hw.h

@@ -142,6 +142,7 @@
 #define GINTSTS_RESETDET		(1 << 23)
 #define GINTSTS_FET_SUSP		(1 << 22)
 #define GINTSTS_INCOMPL_IP		(1 << 21)
+#define GINTSTS_INCOMPL_SOOUT		(1 << 21)
 #define GINTSTS_INCOMPL_SOIN		(1 << 20)
 #define GINTSTS_OEPINT			(1 << 19)
 #define GINTSTS_IEPINT			(1 << 18)