Hello,

On Monday, August 08, 2011 5:22 PM Ramirez Luna, Omar wrote:

On Sun, Jul 31, 2011 at 7:57 PM, KyongHo Cho [off-list ref] wrote:

quoted

On Fri, Jul 29, 2011 at 11:24 PM, Marek Szyprowski

...

quoted

quoted

Right now I have no idea how to handle this better. Perhaps with should be
possible
to specify somehow the target dma_address when doing memory allocation, but

I'm

quoted

quoted

not
really convinced yet if this is really required.

What about using 'dma_handle' argument of alloc_coherent callback of
dma_map_ops?
Although it is an output argument, I think we can convey a hint or
start address to map
to the IO memory manager that resides behind dma API.

I also thought on this one, even dma_map_single receives a void *ptr
which could be casted into a struct with both physical and virtual
addresses to be mapped, but IMHO, this starts to add twists into the
dma map parameters which might create confusion.

Nope, this is completely wrong approach. DMA-mapping is kernel wide, 
architecture independent API and you should not define any exceptions from it.

quoted

DMA API is so abstract that it cannot cover all requirements by
various device drivers;;

Agree.

From my perspective DMA API is quite well designed as cross-architecture API.

The
only problem is the lack of documentation how to use it correctly in the
embedded
world.

Best regards
-- 
Marek Szyprowski
Samsung Poland R&D Center

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