On Sep 8, 2008, at 5:03 PM, Christoph Hellwig wrote:
- if (unlikely(dev == NULL || dev->archdata.dma_ops == NULL))
+
+ if (unlikely(dev == NULL) || dev->archdata.dma_ops == NULL) {
+#ifdef CONFIG_PPC64
return NULL;
+#else
+ /* Use default on 32-bit if dma_ops is not set up */
+ return &dma_direct_ops;
+#endif
+ }
+
This is okay for the transition, but I think long-term it should
be setup for all busses.
Agreed!
}
@@ -132,7 +154,14 @@ static inline dma_addr_t
dma_map_single_attrs(struct device *dev,
struct dma_mapping_ops *dma_ops = get_dma_ops(dev);
BUG_ON(!dma_ops);
- return dma_ops->map_single(dev, cpu_addr, size, direction, attrs);
+
+ if (dma_ops->map_single)
+ return dma_ops->map_single(dev, cpu_addr, size, direction,
+ attrs);
+
+ return dma_ops->map_page(dev, virt_to_page(cpu_addr),
+ (unsigned long)cpu_addr % PAGE_SIZE, size,
+ direction, attrs);
Why would a dma ops implementation not provide map_single/
unmap_single?
.... because you asked me to have just map/unmap_page in your review
of an earlier rev of this patch series in May? :) I don't actually
expect you to remember this, because it was a long time ago, but
here's the relevant chunk of the conversation:
On May 23, 2008, at 4:51 AM, Christoph Hellwig wrote:
On Wed, Apr 30, 2008 at 06:36:43PM -0500, Becky Bruce wrote:
In addition, the dma_map/unmap_page functions are added to dma_ops on
HIGHMEM-enabled configs because we can't just fall back on map/
unmap_single
when HIGHMEM is enabled. Adding these to dma_ops makes it cleaner to
substitute different functionality once we have iommu/swiotlb
support.
Maybe I'm missing something but we should only have the page ones.
virt_to_page is cheap and we'll most likely need the phys address
which
we get from the page anyway.
So I did that for the dma_direct_* ops, but discovered that doing it
for the iommu case (which I can't test and don't fully understand)
would be a bit more complicated. The above code (in conjunction with
the same code for map_page) allows you to have map/unmap_page, map/
unmap_single, or both. I'm happy to change it again, though. We
could just do the above in map_page/unmap_page, calling map/
unmap_single if there is no map/unmap_page, and provide both a
dma_direct_map/unmap_single and a dma_direct_map/unmap_page for the
dma_direct* ops.
Thanks for taking the time to review - I appreciate it!
-Becky
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