USB: s3c-hsotg: Ensure FIFOs are fully flushed after layout

According to the design guide, if the FIFO layout is changed, then the
FIFOs must be flushed to ensure all FIFO pointers are correct.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/s3c-hsotg.c

@@ -300,6 +300,7 @@ static void s3c_hsotg_init_fifo(struct s3c_hsotg *hsotg)
 	unsigned int ep;
 	unsigned int addr;
 	unsigned int size;
+	int timeout;
 	u32 val;
 
 	/* the ryu 2.6.24 release ahs
@@ -335,6 +336,31 @@ static void s3c_hsotg_init_fifo(struct s3c_hsotg *hsotg)
 
 		writel(val, hsotg->regs + S3C_DPTXFSIZn(ep));
 	}
+
+	/* according to p428 of the design guide, we need to ensure that
+	 * all fifos are flushed before continuing */
+
+	writel(S3C_GRSTCTL_TxFNum(0x10) | S3C_GRSTCTL_TxFFlsh |
+	       S3C_GRSTCTL_RxFFlsh, hsotg->regs + S3C_GRSTCTL);
+
+	/* wait until the fifos are both flushed */
+	timeout = 100;
+	while (1) {
+		val = readl(hsotg->regs + S3C_GRSTCTL);
+
+		if ((val & (S3C_GRSTCTL_TxFFlsh | S3C_GRSTCTL_RxFFlsh)) == 0)
+			break;
+
+		if (--timeout == 0) {
+			dev_err(hsotg->dev,
+				"%s: timeout flushing fifos (GRSTCTL=%08x)\n",
+				__func__, val);
+		}
+
+		udelay(1);
+	}
+
+	dev_dbg(hsotg->dev, "FIFOs reset, timeout at %d\n", timeout);
 }
 
 /**