Re: [PATCH v2 11/13] NTB: convert to dmaengine_unmap_data

[Dan Williams]

On Tue, Oct 22, 2013 at 4:12 PM, Jon Mason <jon.mason@xxxxxxxxx> wrote:
> On Tue, Oct 22, 2013 at 02:29:36PM -0700, Dan Williams wrote:
>> On Fri, Oct 18, 2013 at 6:06 PM, Jon Mason <jon.mason@xxxxxxxxx> wrote:
>> > On Fri, Oct 18, 2013 at 07:35:31PM +0200, Bartlomiej Zolnierkiewicz wrote:
>> >> Use the generic unmap object to unmap dma buffers.
>> >>
>> >> As NTB can be compiled without DMA_ENGINE support add
>> >
>> > Seems like the stubs should be added outside of this patch.
>>
>> I think they are ok here as this is the only driver that uses them.
>> The alternative is a new api patch without a user.
>>
>> > Also, the
>> > comment implies that NTB could not be compiled without DMA_ENGINE
>> > support before, which it could be.
>>
>> Hmm, I read it as "since NTB *can* be compiled without dmaengine here
>> are some stubs".
>
> This poses an overall question of whether it would simply be better to
> abstract all of the with/without DMA_ENGINE part and simply remap it
> to memcpy if DMA_ENGINE is not set (or if the DMA engine is
> hotplugged).  Of course, this is outside the scope of this patch.

That's at least the promise of async_memcpy() it does not care if a
channel is there or not, but I think it is better if the client has a
strict dma and non-dma path.  Hiding the dma details from the client
seems to have been the wrong choice at least for raid.

> That is fine.  It can be like this in the short term.
>
> Thanks,
> Jon

I'll take that as:

Acked-by: Jon Mason <jon.mason@xxxxxxxxx>

...but holler if not.
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