staging: comedi: addi_apci_3120: DMA requires an interrupt

An interrupt is required for DMA to work.

Factor out the DMA buffer allocation from the (*auto_attach) and only
allocate the buffers if the interrupt is available.

For aesthetics, also factor the DMA buffer free from the (*detach).
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/addi_apci_3120.c

@@ -61,6 +61,51 @@ struct apci3120_private {
 
 #include "addi-data/hwdrv_apci3120.c"
 
+static void apci3120_dma_alloc(struct comedi_device *dev)
+{
+	struct apci3120_private *devpriv = dev->private;
+	int order;
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		for (order = 2; order >= 0; order--) {
+			devpriv->ul_DmaBufferVirtual[i] =
+			    dma_alloc_coherent(dev->hw_dev, PAGE_SIZE << order,
+					       &devpriv->ul_DmaBufferHw[i],
+					       GFP_KERNEL);
+
+			if (devpriv->ul_DmaBufferVirtual[i])
+				break;
+		}
+		if (!devpriv->ul_DmaBufferVirtual[i])
+			break;
+		devpriv->ui_DmaBufferSize[i] = PAGE_SIZE << order;
+
+		if (i == 0)
+			devpriv->us_UseDma = 1;
+		if (i == 1)
+			devpriv->b_DmaDoubleBuffer = 1;
+	}
+}
+
+static void apci3120_dma_free(struct comedi_device *dev)
+{
+	struct apci3120_private *devpriv = dev->private;
+	int i;
+
+	if (!devpriv)
+		return;
+
+	for (i = 0; i < 2; i++) {
+		if (devpriv->ul_DmaBufferVirtual[i]) {
+			dma_free_coherent(dev->hw_dev,
+					  devpriv->ui_DmaBufferSize[i],
+					  devpriv->ul_DmaBufferVirtual[i],
+					  devpriv->ul_DmaBufferHw[i]);
+		}
+	}
+}
+
 static int apci3120_auto_attach(struct comedi_device *dev,
 				unsigned long context)
 {
@@ -68,7 +113,7 @@ static int apci3120_auto_attach(struct comedi_device *dev,
 	const struct apci3120_board *this_board = NULL;
 	struct apci3120_private *devpriv;
 	struct comedi_subdevice *s;
-	int ret, order, i;
+	int ret;
 
 	if (context < ARRAY_SIZE(apci3120_boardtypes))
 		this_board = &apci3120_boardtypes[context];
@@ -95,30 +140,12 @@ static int apci3120_auto_attach(struct comedi_device *dev,
 	if (pcidev->irq > 0) {
 		ret = request_irq(pcidev->irq, apci3120_interrupt, IRQF_SHARED,
 				  dev->board_name, dev);
-		if (ret == 0)
+		if (ret == 0) {
 			dev->irq = pcidev->irq;
-	}
-
-	/* Allocate DMA buffers */
-	for (i = 0; i < 2; i++) {
-		for (order = 2; order >= 0; order--) {
-			devpriv->ul_DmaBufferVirtual[i] =
-			    dma_alloc_coherent(dev->hw_dev, PAGE_SIZE << order,
-					       &devpriv->ul_DmaBufferHw[i],
-					       GFP_KERNEL);
 
-			if (devpriv->ul_DmaBufferVirtual[i])
-				break;
+			apci3120_dma_alloc(dev);
 		}
-		if (!devpriv->ul_DmaBufferVirtual[i])
-			break;
-		devpriv->ui_DmaBufferSize[i] = PAGE_SIZE << order;
 	}
-	if (devpriv->ul_DmaBufferVirtual[0])
-		devpriv->us_UseDma = 1;
-
-	if (devpriv->ul_DmaBufferVirtual[1])
-		devpriv->b_DmaDoubleBuffer = 1;
 
 	ret = comedi_alloc_subdevices(dev, 5);
 	if (ret)
@@ -193,24 +220,10 @@ static int apci3120_auto_attach(struct comedi_device *dev,
 
 static void apci3120_detach(struct comedi_device *dev)
 {
-	struct apci3120_private *devpriv = dev->private;
-
 	if (dev->iobase)
 		apci3120_reset(dev);
 	comedi_pci_detach(dev);
-	if (devpriv) {
-		unsigned int i;
-
-		for (i = 0; i < 2; i++) {
-			if (devpriv->ul_DmaBufferVirtual[i]) {
-				dma_free_coherent(dev->hw_dev,
-						  devpriv->ui_DmaBufferSize[i],
-						  devpriv->
-						  ul_DmaBufferVirtual[i],
-						  devpriv->ul_DmaBufferHw[i]);
-			}
-		}
-	}
+	apci3120_dma_free(dev);
 }
 
 static struct comedi_driver apci3120_driver = {