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SubjectRE: dmaengine/Query: What about scatter/gather for mem to mem transfers.
Date
> 
> Hello Vinod/Dan,
>
> Please write your opinion.
I am on vacation, but will reply briefly here, more next week
>
> Regards
> Pratyush
>
> On 12/14/2011 12:17 PM, Pratyush Anand wrote:
> > Hello Vinod/Dan,
> >
> > In continuation to the scatter/gather requirement:
> > We might need some generic transfer where source and destination
> > address may be overlapped and also gap between two chunk of source and
> > destination might not be same.
> >
> > For examaple,
> > Transfer size is - -0x4000
> > Our Src is something like this:
> > 0x1000 -- 0x2000
> > 0x3000 -- 0x5000
> > 0x6000 -- 0x7000
> >
> > and dst is something like this:
> > 0x6000 -- 0x8000
> > 0x9000 -- 0xB000
So why can't it be split like:
0x1000--0x2000 => 0x6000 --0x7000
0x3000 -- 0x4000 => 0x7000 - 0x8000
0x4000 -- 0x5000 => 0x9000 - 0xA000
0x6000 -- 0x7000 => 0xA000 - 0xB000

That way existing mechanism would work well for you.
You need to split the chunks properly, which is what dma would do anyway

--
~Vinod
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