staging: comedi: pcl711: don't fail attach if irq is unavailable

Interrupts are only needed to support asynchronous commands with the
analog input subdevice. Since the interrupt is optional during the
attach of the board, don't fail the attach if it's not available.

Also, remove the printk() noise about the irq. The user will know if
the interrupt is available due to the subdev_flag SDF_CMD_READ being
set for the analog input subdevice.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/pcl711.c

@@ -477,29 +477,18 @@ static int pcl711_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	const struct pcl711_board *board = comedi_board(dev);
 	struct pcl711_private *devpriv;
 	int ret;
-	unsigned int irq;
 	struct comedi_subdevice *s;
 
 	ret = comedi_request_region(dev, it->options[0], PCL711_SIZE);
 	if (ret)
 		return ret;
 
-	/* grab our IRQ */
-	irq = it->options[1];
-	if (irq > board->maxirq) {
-		printk(KERN_ERR "irq out of range\n");
-		return -EINVAL;
+	if (it->options[1] && it->options[1] <= board->maxirq) {
+		ret = request_irq(it->options[1], pcl711_interrupt, 0,
+				  dev->board_name, dev);
+		if (ret == 0)
+			dev->irq = it->options[1];
 	}
-	if (irq) {
-		if (request_irq(irq, pcl711_interrupt, 0, dev->board_name,
-			        dev)) {
-			printk(KERN_ERR "unable to allocate irq %u\n", irq);
-			return -EINVAL;
-		} else {
-			printk(KERN_INFO "( irq = %u )\n", irq);
-		}
-	}
-	dev->irq = irq;
 
 	ret = comedi_alloc_subdevices(dev, 4);
 	if (ret)
@@ -518,7 +507,7 @@ static int pcl711_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	s->len_chanlist = 1;
 	s->range_table = board->ai_range_type;
 	s->insn_read = pcl711_ai_insn;
-	if (irq) {
+	if (dev->irq) {
 		dev->read_subdev = s;
 		s->subdev_flags |= SDF_CMD_READ;
 		s->do_cmdtest = pcl711_ai_cmdtest;