Staging: comedi: convert while loop to timeout in ni_mio_common.c

This patch for ni_mio_common.c changes out a while loop for a timeout,
which is preferred.
Signed-off-by: NChase Southwood <chase.southwood@yahoo.com>
Reviewed-by: NIan Abbott <abbotti@mev.co.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_mio_common.c

@@ -687,12 +687,22 @@ static void ni_clear_ai_fifo(struct comedi_device *dev)
 {
 	const struct ni_board_struct *board = comedi_board(dev);
 	struct ni_private *devpriv = dev->private;
+	static const int timeout = 10000;
+	int i;
 
 	if (board->reg_type == ni_reg_6143) {
 		/*  Flush the 6143 data FIFO */
 		ni_writel(0x10, AIFIFO_Control_6143);	/*  Flush fifo */
 		ni_writel(0x00, AIFIFO_Control_6143);	/*  Flush fifo */
-		while (ni_readl(AIFIFO_Status_6143) & 0x10) ;	/*  Wait for complete */
+		/*  Wait for complete */
+		for (i = 0; i < timeout; i++) {
+			if (!(ni_readl(AIFIFO_Status_6143) & 0x10))
+				break;
+			udelay(1);
+		}
+		if (i == timeout) {
+			comedi_error(dev, "FIFO flush timeout.");
+		}
 	} else {
 		devpriv->stc_writew(dev, 1, ADC_FIFO_Clear);
 		if (board->reg_type == ni_reg_625x) {