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SubjectRe: [PATCHv3] DMAEngine: Define interleaved transfer request api
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On 21 September 2011 12:02, Vinod Koul <vinod.koul@intel.com> wrote:
> On Tue, 2011-09-20 at 23:38 +0530, Jassi Brar wrote:
>> On 20 September 2011 22:22, Vinod Koul <vinod.koul@intel.com> wrote:
>> > Also for slave transfers, how do we infer direction?
>> I already explained to Barry.  Here's it again.
>>
>> At any time, the dmac driver knows if the channel, on which the xfer is
>> prepared/submitted is Slave or not.
>>
>> SLAVE Transfer
>>    dmaxfer_template.src_inc  && !dmaxfer_template.dst_inc  => DMA_TO_DEVICE
>>    !dmaxfer_template.src_inc  && dmaxfer_template.dst_inc  => DMA_FROM_DEVICE
>>
>> Mem->Mem Transfer
>>    dmaxfer_template.src_inc  && !dmaxfer_template.dst_inc  => Meaningless
>>    !dmaxfer_template.src_inc  && dmaxfer_template.dst_inc  => MemSet
> Rather than each driver adding this logic with good chance of screwing
> up, care to add this as helper in dmaengine.h
>
> Ideally, I would have preferred direction to be told explicitly, would
> leave it you..
>
I repeat yet again :- "This api is common to Slave as well as Mem<->Mem"

Even if we have slave clients specify DMA_TO/FROM_DEVICE, what
flag do you suggest Mem->Mem clients use ?
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