atl1: disable broken 64-bit DMA
[ Upstream commit: 5f08e46b621a769e52a9545a23ab1d5fb2aec1d4 ]
The L1 network chip can DMA to 64-bit addresses, but multiple descriptor
rings share a single register for the high 32 bits of their address, so
only a single, aligned, 4 GB physical address range can be used at a time.
As a result, we need to confine the driver to a 32-bit DMA mask, otherwise
we see occasional data corruption errors in systems containing 4 or more
gigabytes of RAM.
Signed-off-by: Jay Cliburn <[email protected]>
Cc: Luca Tettamanti <[email protected]>
Cc: Chris Snook <[email protected]>
---
drivers/net/atl1/atl1_main.c | 25 +++++++++++++------------
1 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/drivers/net/atl1/atl1_main.c b/drivers/net/atl1/atl1_main.c
index 6862c11..1b7a5a8 100644
--- a/drivers/net/atl1/atl1_main.c
+++ b/drivers/net/atl1/atl1_main.c
@@ -2097,21 +2097,26 @@ static int __devinit atl1_probe(struct pci_dev *pdev,
struct net_device *netdev;
struct atl1_adapter *adapter;
static int cards_found = 0;
- bool pci_using_64 = true;
int err;
err = pci_enable_device(pdev);
if (err)
return err;
- err = pci_set_dma_mask(pdev, DMA_64BIT_MASK);
+ /*
+ * 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) {
- err = pci_set_dma_mask(pdev, DMA_32BIT_MASK);
- if (err) {
- dev_err(&pdev->dev, "no usable DMA configuration\n");
- goto err_dma;
- }
- pci_using_64 = false;
+ dev_err(&pdev->dev, "no usable DMA configuration\n");
+ goto err_dma;
}
/* Mark all PCI regions associated with PCI device
* pdev as being reserved by owner atl1_driver_name
@@ -2176,7 +2181,6 @@ static int __devinit atl1_probe(struct pci_dev *pdev,
netdev->ethtool_ops = &atl1_ethtool_ops;
adapter->bd_number = cards_found;
- adapter->pci_using_64 = pci_using_64;
/* setup the private structure */
err = atl1_sw_init(adapter);
@@ -2193,9 +2197,6 @@ static int __devinit atl1_probe(struct pci_dev *pdev,
*/
/* netdev->features |= NETIF_F_TSO; */
- if (pci_using_64)
- netdev->features |= NETIF_F_HIGHDMA;
-
netdev->features |= NETIF_F_LLTX;
/*
--
1.5.3.3
-
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