Re: [Linux-c6x-dev] [PATCH 3/9] c6x: Provide dma_mmap_coherent()and dma_get_sgtable()

[Vineet Gupta]

On Monday 14 January 2013 09:07 PM, Mark Salter wrote:
> On Sun, 2013-01-13 at 11:44 +0100, Geert Uytterhoeven wrote:
>> c6x/allmodconfig (assumed):
>>
>> drivers/media/v4l2-core/videobuf2-dma-contig.c: In function ʽvb2_dc_mmapʼ:
>> drivers/media/v4l2-core/videobuf2-dma-contig.c:204: error: implicit declaration of function ʽdma_mmap_coherentʼ
>> drivers/media/v4l2-core/videobuf2-dma-contig.c: In function ʽvb2_dc_get_base_sgtʼ:
>> drivers/media/v4l2-core/videobuf2-dma-contig.c:387: error: implicit declaration of function ʽdma_get_sgtableʼ
>>
>> For architectures using dma_map_ops, dma_mmap_coherent() and
>> dma_get_sgtable() are provided in <asm-generic/dma-mapping-common.h>.
>>
>> C6x does not use dma_map_ops, hence it should implement them as inline
>> stubs using dma_common_mmap() and dma_common_get_sgtable().
>>
> 
> So are dma_mmap_coherent() and dma_get_sgtable() part of the DMA API
> now? I don't them in Documentation/DMA*.txt anywhere.
> 
> Why does the default dma_common_mmap() for !CONFIG_MMU return an
> error?
> 
> Wouldn't it be better to provide default implementations that an arch
> could override rather than having to patch all "no dma_map_ops"
> architectures?
> 
> --Mark
> 
> 

Speaking for the still-reviewed ARC Port, I completely agree with Mark.

-Vineet
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