Re: USB and DMA on Alpha with 2.6.0-test7

[David Brownell <david-b@pacbell.net>]

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> Ivan Kokshaysky wrote:
>>
>> This doesn't work. You will always return success if mask = ~0ULL.

Whoops.  I didn't copy what I thought I was copying:

            (mask & *dev->dma_mask) == mask  /* not "== dma_mask" */

Updated code is appended ... which also provides a BUG()-free
version of dma_set_mask().  I think the only arch/platform hook
needed would be for dma_supported().

- Dave


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--- 1.4/include/asm-generic/dma-mapping.h	Mon Jan 13 14:37:47 2003
+++ edited/include/asm-generic/dma-mapping.h	Sat Oct 11 15:33:56 2003
@@ -13,20 +13,22 @@
 /* need struct page definitions */
 #include <linux/mm.h>
 
+/* FIXME use this everywhere there's no platform_dma_supported() */
 static inline int
 dma_supported(struct device *dev, u64 mask)
 {
-	BUG_ON(dev->bus != &pci_bus_type);
-
-	return pci_dma_supported(to_pci_dev(dev), mask);
+	/* device can dma, using those address bits */
+	return dev->dma_mask
+		&& (mask & *dev->dma_mask) == mask;
 }
 
 static inline int
-dma_set_mask(struct device *dev, u64 dma_mask)
+dma_set_mask(struct device *dev, u64 mask)
 {
-	BUG_ON(dev->bus != &pci_bus_type);
-
-	return pci_set_dma_mask(to_pci_dev(dev), dma_mask);
+	if (!dma_supported(dev, mask))
+		return 0;
+	*dev->dma_mask = mask;
+	return 1;
 }
 
 static inline void *