[PATCH v3 1/1] usb: dwc2: gadget: parity fix in isochronous mode

[Scott Branden <sbranden@broadcom.com>]

From: Roman Bacik <rbacik@broadcom.com>

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>
---
 drivers/usb/dwc2/core.h   |  1 +
 drivers/usb/dwc2/gadget.c | 58 ++++++++++++++++++++++++++++++++++++++++++-----
 drivers/usb/dwc2/hw.h     |  1 +
 3 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index 0ed87620..a5634fd 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -150,6 +150,7 @@ struct s3c_hsotg_ep {
 	unsigned int            periodic:1;
 	unsigned int            isochronous:1;
 	unsigned int            send_zlp:1;
+	unsigned int            has_correct_parity:1;
 
 	char                    name[10];
 };
diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index 4d47b7c..efaab76 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -1916,6 +1916,19 @@ static void s3c_hsotg_complete_in(struct dwc2_hsotg *hsotg,
 	s3c_hsotg_complete_request(hsotg, hs_ep, hs_req, 0);
 }
 
+static void s3c_hsotg_change_ep_iso_parity(struct dwc2_hsotg *hsotg,
+			u32 epctl_reg)
+{
+	u32 ctrl;
+
+	ctrl = readl(hsotg->regs + epctl_reg);
+	if (ctrl & DXEPCTL_EOFRNUM)
+		ctrl |= DXEPCTL_SETEVENFR;
+	else
+		ctrl |= DXEPCTL_SETODDFR;
+	writel(ctrl, hsotg->regs + epctl_reg);
+}
+
 /**
  * s3c_hsotg_epint - handle an in/out endpoint interrupt
  * @hsotg: The driver state
@@ -1954,12 +1967,9 @@ static void s3c_hsotg_epint(struct dwc2_hsotg *hsotg, unsigned int idx,
 		ints &= ~DXEPINT_XFERCOMPL;
 
 	if (ints & DXEPINT_XFERCOMPL) {
+		hs_ep->has_correct_parity = 1;
 		if (hs_ep->isochronous && hs_ep->interval == 1) {
-			if (ctrl & DXEPCTL_EOFRNUM)
-				ctrl |= DXEPCTL_SETEVENFR;
-			else
-				ctrl |= DXEPCTL_SETODDFR;
-			writel(ctrl, hsotg->regs + epctl_reg);
+			s3c_hsotg_change_ep_iso_parity(hsotg, epctl_reg);
 		}
 
 		dev_dbg(hsotg->dev,
@@ -2316,7 +2326,8 @@ void s3c_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,
 		GINTSTS_CONIDSTSCHNG | GINTSTS_USBRST |
 		GINTSTS_RESETDET | GINTSTS_ENUMDONE |
 		GINTSTS_OTGINT | GINTSTS_USBSUSP |
-		GINTSTS_WKUPINT,
+		GINTSTS_WKUPINT |
+		GINTSTS_INCOMPL_SOIN | GINTSTS_INCOMPL_SOOUT,
 		hsotg->regs + GINTMSK);
 
 	if (using_dma(hsotg))
@@ -2581,6 +2592,40 @@ irq_retry:
 		s3c_hsotg_dump(hsotg);
 	}
 
+	if (gintsts & GINTSTS_INCOMPL_SOIN) {
+		u32 idx, epctl_reg;
+		struct s3c_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);
+			s3c_hsotg_change_ep_iso_parity(hsotg, epctl_reg);
+		}
+		writel(GINTSTS_INCOMPL_SOIN, hsotg->regs + GINTSTS);
+	}
+
+	if (gintsts & GINTSTS_INCOMPL_SOOUT) {
+		u32 idx, epctl_reg;
+		struct s3c_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);
+			s3c_hsotg_change_ep_iso_parity(hsotg, epctl_reg);
+		}
+		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.
@@ -2667,6 +2712,7 @@ static int s3c_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");
diff --git a/drivers/usb/dwc2/hw.h b/drivers/usb/dwc2/hw.h
index d0a5ed8..553f246 100644
--- a/drivers/usb/dwc2/hw.h
+++ b/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)
-- 
2.5.0