Messages in this thread | | | From | Dan Malek <> | Subject | Re: [PATCH] fsldma: add support to 36-bit physical address | Date | Tue, 21 Sep 2010 15:05:05 -0700 |
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On Sep 21, 2010, at 2:49 PM, Scott Wood wrote:
> > On Tue, 21 Sep 2010 16:43:12 -0500 > Timur Tabi <timur.tabi@gmail.com> wrote: > >> Since we don't DMA the descriptors themselves, I just don't see how >> this patch does anything. > > Look in dmaengine.c, there are calls to dma_map_single() and > dma_map_page(), using what I assume is that same device pointer -- > unless there's confusion between the channel and the controller.
The DMA descriptors are accessed using DMA by the controller itself. The APIs need to ensure proper coherency between the CPU and the DMA controller for the descriptor access. The underlying implementation of the API will depend upon the hardware capabilities that ensure this coherency.
-- Dan
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