[PATCH] fsldma: use PCI Read Multiple command

Kumar Gala galak at kernel.crashing.org
Tue Apr 28 06:02:03 EST 2009


On Apr 27, 2009, at 3:00 PM, David Hawkins wrote:

>
>>> Can you give me an example of non-PCI memory that would be
>>> non-prefetchable that you'd like us to try? We can see if our
>>> host CPUs have an area like that ... we just need to know
>>> what device to look for first :)
>> You can mark the pci inbound window on the 83xx as non-prefetchable  
>> (assuming 83xx is host). On a x86 host I doubt there is any easy  
>> way to get non-prefetchable memory.
>
> Yep, we were going to do that, but chose to use the
> 1MB region already setup for the IMMRs since its already
> marked as non-prefetchable. We were only doing reads, so
> it wasn't going to hurt anything.
>
> I doubt that marking one of the other BAR regions
> as non-prefetchable will give a different result.
> However, we're more than happy to double-check if
> you'd like.

Its possible you'll get a different result since IMMR is a register  
space internal and thats normally a completely different bus than  
memory would be (internal to the 83xx).  I'd suggest double-checking w/ 
a BAR marked non-prefetch pointing to real memory.

- k



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