diff options
| -rw-r--r-- | drivers/net/atl1/atl1_main.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/net/atl1/atl1_main.c b/drivers/net/atl1/atl1_main.c index e1a9223d0c1..4c728f1169c 100644 --- a/drivers/net/atl1/atl1_main.c +++ b/drivers/net/atl1/atl1_main.c @@ -2209,8 +2209,14 @@ static int __devinit atl1_probe(struct pci_dev *pdev, return err; /* - * 64-bit DMA currently has data corruption problems, so let's just - * use 32-bit DMA for now. This is a big hack that is probably wrong. + * The atl1 chip can DMA to 64-bit addresses, but it uses a single + * shared register for the high 32 bits, so only a single, aligned, + * 4 GB physical address range can be used at a time. + * + * Supporting 64-bit DMA on this hardware is more trouble than it's + * worth. It is far easier to limit to 32-bit DMA than update + * various kernel subsystems to support the mechanics required by a + * fixed-high-32-bit system. */ err = pci_set_dma_mask(pdev, DMA_32BIT_MASK); if (err) { |