driver/net: enic: Try DMA 64 first, then failover to DMA

In servers with more than 1.1 TB of RAM, the existing 40/32 bit DMA
could cause failure as the DMA-able address could go outside the range
addressable using 40/32 bits.

The following patch first tried 64 bit DMA if possible, failover to 32
bit.
Signed-off-by: Sujith Sankar <ssujith@cisco.com>
Signed-off-by: Christian Benvenuti <benve@cisco.com>
Signed-off-by: Govindarajulu Varadarajan <govindarajulu90@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cisco/enic/enic_main.c

@@ -2080,11 +2080,11 @@ static int enic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	pci_set_master(pdev);
 
 	/* Query PCI controller on system for DMA addressing
-	 * limitation for the device.  Try 40-bit first, and
+	 * limitation for the device.  Try 64-bit first, and
 	 * fail to 32-bit.
 	 */
 
-	err = pci_set_dma_mask(pdev, DMA_BIT_MASK(40));
+	err = pci_set_dma_mask(pdev, DMA_BIT_MASK(64));
 	if (err) {
 		err = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
 		if (err) {
@@ -2098,10 +2098,10 @@ static int enic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 			goto err_out_release_regions;
 		}
 	} else {
-		err = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(40));
+		err = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(64));
 		if (err) {
 			dev_err(dev, "Unable to obtain %u-bit DMA "
-				"for consistent allocations, aborting\n", 40);
+				"for consistent allocations, aborting\n", 64);
 			goto err_out_release_regions;
 		}
 		using_dac = 1;