diff --git a/drivers/staging/comedi/drivers/pcl818.c b/drivers/staging/comedi/drivers/pcl818.c
index 6c91a7b424d8..d00d6902c4a6 100644
--- a/drivers/staging/comedi/drivers/pcl818.c
+++ b/drivers/staging/comedi/drivers/pcl818.c
@@ -732,8 +732,9 @@ static irqreturn_t interrupt_pcl818(int irq, void *d)
 	struct pcl818_private *devpriv = dev->private;
 	struct comedi_subdevice *s = dev->read_subdev;
 
-	if (!dev->attached) {
-		comedi_error(dev, "premature interrupt");
+	if (!dev->attached || !devpriv->ai_cmd_running ||
+	    !devpriv->ai_mode) {
+		outb(0, dev->iobase + PCL818_CLRINT);
 		return IRQ_HANDLED;
 	}
 
@@ -764,15 +765,8 @@ static irqreturn_t interrupt_pcl818(int irq, void *d)
 		break;
 	}
 
-	outb(0, dev->iobase + PCL818_CLRINT);	/* clear INT request */
-
-	if (!devpriv->ai_cmd_running || !devpriv->ai_mode) {
-		comedi_error(dev, "bad IRQ!");
-		return IRQ_NONE;
-	}
-
-	comedi_error(dev, "IRQ from unknown source!");
-	return IRQ_NONE;
+	outb(0, dev->iobase + PCL818_CLRINT);
+	return IRQ_HANDLED;
 }
 
 static void pcl818_ai_mode13dma_int(int mode, struct comedi_device *dev,