[TG3]: Fix 5700/5701 DMA corruption on Apple G4.

Fix 5700/5701 DMA write corruption on Apple G4 by detecting the Apple
UniNorth PCI 1.5 chipset and adjusting the DMA write boundary to 16. DMA
test fails to detect the problem with this chipset.

Thanks to Manuel Perez Ayala for reporting the problem and helping to
debug it.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 2 deletions

diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index e944aac258e3..77337c3b4285 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -9695,10 +9695,24 @@ static int __devinit tg3_test_dma(struct tg3 *tp)
         }
         if ((tp->dma_rwctrl & DMA_RWCTRL_WRITE_BNDRY_MASK) !=
             DMA_RWCTRL_WRITE_BNDRY_16) {
+                static struct pci_device_id dma_wait_state_chipsets[] = {
+                        { PCI_DEVICE(PCI_VENDOR_ID_APPLE,
+                                     PCI_DEVICE_ID_APPLE_UNI_N_PCI15) },
+                        { },
+                };
+
                 /* DMA test passed without adjusting DMA boundary,
-                 * just restore the calculated DMA boundary
+                 * now look for chipsets that are known to expose the
+                 * DMA bug without failing the test.
                  */
-                tp->dma_rwctrl = saved_dma_rwctrl;
+                if (pci_dev_present(dma_wait_state_chipsets)) {
+                        tp->dma_rwctrl &= ~DMA_RWCTRL_WRITE_BNDRY_MASK;
+                        tp->dma_rwctrl |= DMA_RWCTRL_WRITE_BNDRY_16;
+                }
+                else
+                        /* Safe to use the calculated DMA boundary. */
+                        tp->dma_rwctrl = saved_dma_rwctrl;
+
                 tw32(TG3PCI_DMA_RW_CTRL, tp->dma_rwctrl);
         }