ahci: use dma_set_mask_and_coherent

Use the dma_set_mask_and_coherent helper to set the DMA mask.  Rely
on the relatively recent change that setting a larger than required
mask will never fail to avoid the need for the boilerplate 32-bit
fallback code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/ata/ahci.c

@@ -901,40 +901,23 @@ static int ahci_pci_device_resume(struct device *dev)
 
 static int ahci_configure_dma_masks(struct pci_dev *pdev, int using_dac)
 {
+	const int dma_bits = using_dac ? 64 : 32;
 	int rc;
 
 	/*
 	 * If the device fixup already set the dma_mask to some non-standard
 	 * value, don't extend it here. This happens on STA2X11, for example.
+	 *
+	 * XXX: manipulating the DMA mask from platform code is completely
+	 * bogus, platform code should use dev->bus_dma_mask instead..
 	 */
 	if (pdev->dma_mask && pdev->dma_mask < DMA_BIT_MASK(32))
 		return 0;
 
-	if (using_dac &&
-	    !dma_set_mask(&pdev->dev, DMA_BIT_MASK(64))) {
-		rc = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
-		if (rc) {
-			rc = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
-			if (rc) {
-				dev_err(&pdev->dev,
-					"64-bit DMA enable failed\n");
-				return rc;
-			}
-		}
-	} else {
-		rc = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
-		if (rc) {
-			dev_err(&pdev->dev, "32-bit DMA enable failed\n");
-			return rc;
-		}
-		rc = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
-		if (rc) {
-			dev_err(&pdev->dev,
-				"32-bit consistent DMA enable failed\n");
+	rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(dma_bits));
+	if (rc)
+		dev_err(&pdev->dev, "DMA enable failed\n");
 	return rc;
-		}
-	}
-	return 0;
 }
 
 static void ahci_pci_print_info(struct ata_host *host)