fsl/usb: Increase TXFIFOTHRESH value for usb write in T4 Rev 2.0

index 1ca7cf5..991b43b 100644
@@ -17,6 +17,8 @@
 
 #include "ehci.h"
 
+static void set_txfifothresh(struct usb_ehci *, u32);
+
 /* Check USB PHY clock valid */
 static int usb_phy_clk_valid(struct usb_ehci *ehci)
 {

@@ -109,6 +111,10 @@ int ehci_hcd_init(int index, enum usb_init_type init,
 
 	in_le32(&ehci->usbmode);
 
+	if (SVR_SOC_VER(get_svr()) == SVR_T4240 &&
+	    IS_SVR_REV(get_svr(), 2, 0))
+		set_txfifothresh(ehci, TXFIFOTHRESH);
+
 	return 0;
 }
 

@@ -120,3 +126,17 @@ int ehci_hcd_stop(int index)
 {
 	return 0;
 }
+
+/*
+ * Setting the value of TXFIFO_THRESH field in TXFILLTUNING register
+ * to counter DDR latencies in writing data into Tx buffer.
+ * This prevents Tx buffer from getting underrun
+ */
+static void set_txfifothresh(struct usb_ehci *ehci, u32 txfifo_thresh)
+{
+	u32 cmd;
+	cmd = ehci_readl(&ehci->txfilltuning);
+	cmd &= ~TXFIFO_THRESH_MASK;
+	cmd |= TXFIFO_THRESH(txfifo_thresh);
+	ehci_writel(&ehci->txfilltuning, cmd);
+}

index 734305b..c9ee1d5 100644
@@ -164,6 +164,13 @@
 #endif
 
 /*
+ * Increasing TX FIFO threshold value from 2 to 4 decreases
+ * data burst rate with which data packets are posted from the TX
+ * latency FIFO to compensate for latencies in DDR pipeline during DMA
+ */
+#define TXFIFOTHRESH		4
+
+/*
  * USB Registers
  */
 struct usb_ehci {