Subject: Cortex A9 with ACP needing mixed coherency model

From: [email-masked] (Rob Herring)
Date: Fri, 24 Aug 2012 08:05:50 -0500

On 08/24/2012 03:54 AM, Will Deacon wrote:
> On Fri, Aug 24, 2012 at 01:58:50AM +0100, John Linn wrote:
>> It doesn't look like there's any good way to have a mixed coherency
>> model to support using the ACP where there is coherency and using
>> other ports where there is not coherency.
>> ARM Linux kernel can support arch_is_coherent(), which means all DMA
>> I/O is coherent. We have multiple DMA engines and they can go to thru
>> coherent or non-coherent ports.
>>
>> Am I missing something, or has someone figured out a way to deal with this?
> 
> Didn't Rob have a crack at fixing this with his recent DMA series?
> 
>   http://lists.infradead.org/pipermail/linux-arm-kernel/2012-August/113929.html
> 
> It's a really nice set of patches, so take a look.

It's queued up in Marek's dma-mapping tree for 3.7.

Rob