Grant Grundler wrote:
On Sat, Aug 9, 2008 at 11:21 AM, Stefan Richter
- orb->page_table[j].low = cpu_to_be32(sg_addr);
- orb->page_table[j].high = cpu_to_be32(l << 16);
I didn't check the rest of the driver - but it would be good if it
explicitly called dma_set_mask() or pci_dma_set_mask() with a 32-bit
mask value. Most drivers assume 32-bit and that's why I point this
out.
I thought about this and currently think that I should not do this.
There is the API to set the mask, but there is no API to _decrease_ the
mask only. The SBP-2 protocol driver should not set DMA_32BIT_MASK if
any other driver already set for example DMA_31BIT_MASK for whatever reason.
For now, this is no issue. FireWire low-level drivers exist only for
controllers with 32 bit local bus addressing capability. I am sure that
somebody will remember to modify the SBP-2 driver(s) if there will ever
be a controller type and a driver for it which can address more than 4 GB.
On the other hand, we also currently have no reason to set a smaller
mask. We recently discovered a chip bug which requires DMA_31BIT_MASK
for a special mode of data reception (only for cache-coherent DMA
though), but we now work around this chip bug by simply falling back to
an alternative mode.
--
Stefan Richter
-=====-==--- =--- -==-=
http://arcgraph.de/sr/
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