Re: [PATCH 1/2] dmadevices: dma_sync_wait undefined

[Jon Mason <jon.mason@intel.com>]

On Thu, Jun 20, 2013 at 02:20:30PM -0700, Dan Williams wrote:
> On Wed, Jun 19, 2013 at 9:28 AM, Jon Mason <jon.mason@intel.com> wrote:
> > On Tue, Jun 18, 2013 at 06:13:28PM -0700, Dan Williams wrote:
> [..]
> > NTB is currently using it to flush any pending DMAs.  This is needed
> > to allow the DMA engine and the CPU to perform operations on the same
> > "Memory Window".  Without this, it is possible for the operations to
> > complete out of order, which is not a desired outcome for any network
> > traffic over NTB.  CPU is preferred over DMA engine for small
> > transfers.  Also, it provides an alternative for errors in the DMA
> > engine copy process (e.g., DMA mapping, device_prep_dma_memcpy, and
> > dmaengine_submit).
> 
> Ok there really isn't a better alternative, is NTB always polling or
> does it also use completion callbacks?

It uses the callbacks.  I've change the code to use dma_find_channel,
and will push it for review as a RFC shortly.

Thanks,
Jon