On Wed, Aug 11, 2010 at 11:06:00AM +0900, FUJITA Tomonori wrote:

On Tue, 10 Aug 2010 22:36:21 +0200
Krzysztof Halasa [off-list ref] wrote:

quoted

6fee48cd330c68332f9712bc968d934a1a84a32a broke
pci_set_consistent_dma_mask() on IXP4xx and most probably PXA. Affected
devices are e.g. IDE controller (CS5536-based: disk inaccessible) and
e1000 ethernet ("Detected Tx Unit Hang").

Sorry about that.

quoted

The attached patch makes it work again, though I'm not sure it's the
best solution.

I think that we should avoid adding "#ifdef CONFIG_DMABOUNCE" to a
generic place.

Why the above patch breaks dmabounce.c? We can't set dev->coherent_dma_mask?

It doesn't break dmabounce.

What it breaks is the fact that a PCI device which can do 32-bit DMA is
connected to a PCI bus which can only access the first 64MB of memory
through the host bridge, but the system has more than 64MB available.

Allowing a 32-bit DMA mask means that dmabounce can't detect that memory
above 64MB needs to be bounced to memory below the 64MB boundary.