Follow-up on "WARNING: at arch/arm/mm/consistent.c:368 dma_free_coherent"

Greg Lee glee-list at
Mon Sep 21 20:40:05 EDT 2009

On Mon, Sep 21, 2009 at 8:00 PM, Greg Lee <glee-list at> wrote:
> I then found a recently updated patch from Mikael that appears to
> address this problem here
> (
> This updated patch does not appear to account for the 4K region at the
> end of the 64MB PCI window that I mentioned above.  Does this region
> in fact need to be accounted for?  Or has this now been handled
> differently?

Ahh!  I just found this discussion here
where Krzysztof Halasa discovers that BAR4 can be mapped after the
64MB PCI window to prevent hangs.  So, this 4K region issue is not a
problem if Kryzsztof's BAR4 patch is in place which it is in 2.6.31
where we are testing.

Now I need to figure out why our USB devices are not working when we
use Mikael's no dmabounce patch.


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