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From: Jon Mason <jon.mason@intel.com>
To: Dan Williams <djbw@fb.com>
Cc: Vinod Koul <vinod.koul@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] dmadevices: dma_sync_wait undefined
Date: Wed, 26 Jun 2013 16:47:04 -0700	[thread overview]
Message-ID: <20130626234704.GG3344@jonmason-lab> (raw)
In-Reply-To: <CAA9_cmehScXsCgxwTHxSJ-KXaa52itDoY+3j1Yajnpy-GFU7Hg@mail.gmail.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

  reply	other threads:[~2013-06-26 23:47 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-19  0:46 [PATCH 0/2] DMA Offload fixes Jon Mason
2013-06-19  0:46 ` [PATCH 1/2] dmadevices: dma_sync_wait undefined Jon Mason
2013-06-19  1:13   ` Dan Williams
2013-06-19 16:28     ` Jon Mason
2013-06-20 21:20       ` Dan Williams
2013-06-26 23:47         ` Jon Mason [this message]
2013-06-19  0:46 ` [PATCH 2/2] ioatdma: add DMA_PRIVATE capabilities flag Jon Mason
2013-06-19  0:59   ` Dan Williams
2013-06-19 17:36     ` Dave Jiang
2013-06-19 17:52     ` Jon Mason
2013-06-19 18:56       ` Dan Williams
2013-06-19 20:10         ` Jon Mason
2013-06-19 20:44           ` Dan Williams
2013-06-26 23:55             ` Jon Mason
2013-06-27  1:10               ` Dan Williams

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