---

yaml --- r: 66843 b: refs/heads/master c: cdcc520 h: refs/heads/master i: 66841: f11ae45 66839: c253a5d v: v3
git-mirror · Oct 10, 2007 · b801084 · b801084
1 parent 2811fb6
commit b801084
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Showing 2 changed files with 9 additions and 3 deletions.
diff --git a/[refs] b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 01faccbf866195831af202de59f37e29467a3d74
+refs/heads/master: cdcc520d7b73445c3552a70786afed9a2b22c010
diff --git a/trunk/drivers/net/atl1/atl1_main.c b/trunk/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) {