Re: [RFC PATCH] arm: dma-mapping: fallback allocation for cma failure

[Gioh Kim <gioh.kim@lge.com>]

2014-05-20 i??i?? 5:32, Joonsoo Kim i?' e,?:
> On Tue, May 20, 2014 at 04:05:52PM +0900, Gioh Kim wrote:
>> That case, device-specific coherent memory allocation, is handled at dma_alloc_coherent in arm_dma_alloc.
>> __dma_alloc handles only general coherent memory allocation.
>>
>> I'm sorry missing mention about it.
>>
>
> Hello,
>
> AFAIK, *coherent* memory allocation is different with *contiguous* memory
> allocation(CMA). So we need to handle the case I mentioned.

Yes, I confused the coherent memory aand contiguous memory. It's my mistake.

So I checked dma_alloc_from_contiguous and found dev_get_cma_area function.
The dev_get_cma_area returns device-specific cma if it exists or default global-cma.
I think __alloc_from_contiguous doesn't distinguish device-specific cma area and global cma.
The purpose of __alloc_from_contiguous is allocation of contiguous memory from any cma area, not device-specific area.

If my assumption is right, __alloc_from_contiguous can be replaced with __alloc_remap_buffer without checking device-specific cma area.

What do you think about it?

>
> Thanks.
>

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