* Cortex A9 with ACP needing mixed coherency model
@ 2012-08-24 0:58 John Linn
2012-08-24 8:54 ` Will Deacon
0 siblings, 1 reply; 3+ messages in thread
From: John Linn @ 2012-08-24 0:58 UTC (permalink / raw)
To: linux-arm-kernel
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?
Thanks,
John
^ permalink raw reply [flat|nested] 3+ messages in thread
* Cortex A9 with ACP needing mixed coherency model
2012-08-24 0:58 Cortex A9 with ACP needing mixed coherency model John Linn
@ 2012-08-24 8:54 ` Will Deacon
2012-08-24 13:05 ` Rob Herring
0 siblings, 1 reply; 3+ messages in thread
From: Will Deacon @ 2012-08-24 8:54 UTC (permalink / raw)
To: linux-arm-kernel
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.
Will
^ permalink raw reply [flat|nested] 3+ messages in thread
* Cortex A9 with ACP needing mixed coherency model
2012-08-24 8:54 ` Will Deacon
@ 2012-08-24 13:05 ` Rob Herring
0 siblings, 0 replies; 3+ messages in thread
From: Rob Herring @ 2012-08-24 13:05 UTC (permalink / raw)
To: linux-arm-kernel
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
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-08-24 0:58 Cortex A9 with ACP needing mixed coherency model John Linn
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