skge: add quirk to limit DMA

Skge devices installed on some Gigabyte motherboards are not able to
perform 64 dma correctly due to board PCI implementation, so limit
DMA to 32bit if such boards are detected.

Bug was reported here:
https://bugzilla.redhat.com/show_bug.cgi?id=447489

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Tested-by: Luya Tshimbalanga <luya@fedoraproject.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/skge.c

@@ -43,6 +43,7 @@
 #include <linux/seq_file.h>
 #include <linux/mii.h>
 #include <linux/slab.h>
+#include <linux/dmi.h>
 #include <asm/irq.h>
 
 #include "skge.h"
@@ -3868,6 +3869,8 @@ static void __devinit skge_show_addr(struct net_device *dev)
 	netif_info(skge, probe, skge->netdev, "addr %pM\n", dev->dev_addr);
 }
 
+static int only_32bit_dma;
+
 static int __devinit skge_probe(struct pci_dev *pdev,
 				const struct pci_device_id *ent)
 {
@@ -3889,7 +3892,7 @@ static int __devinit skge_probe(struct pci_dev *pdev,
 
 	pci_set_master(pdev);
 
-	if (!pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) {
+	if (!only_32bit_dma && !pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) {
 		using_dac = 1;
 		err = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(64));
 	} else if (!(err = pci_set_dma_mask(pdev, DMA_BIT_MASK(32)))) {
@@ -4147,8 +4150,21 @@ static struct pci_driver skge_driver = {
 	.shutdown =	skge_shutdown,
 };
 
+static struct dmi_system_id skge_32bit_dma_boards[] = {
+	{
+		.ident = "Gigabyte nForce boards",
+		.matches = {
+			DMI_MATCH(DMI_BOARD_VENDOR, "Gigabyte Technology Co"),
+			DMI_MATCH(DMI_BOARD_NAME, "nForce"),
+		},
+	},
+	{}
+};
+
 static int __init skge_init_module(void)
 {
+	if (dmi_check_system(skge_32bit_dma_boards))
+		only_32bit_dma = 1;
 	skge_debug_init();
 	return pci_register_driver(&skge_driver);
 }