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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 2/2] ioatdma: add DMA_PRIVATE capabilities flag
Date: Wed, 19 Jun 2013 13:10:54 -0700	[thread overview]
Message-ID: <20130619201054.GA20996@jonmason-lab> (raw)
In-Reply-To: <CAA9_cmdVfFmD5Li4b8WEtAiqCiSCKYuva_86MLV3ysAhyLXtig@mail.gmail.com>

On Wed, Jun 19, 2013 at 11:56:38AM -0700, Dan Williams wrote:
> On Wed, Jun 19, 2013 at 10:52 AM, Jon Mason <jon.mason@intel.com> wrote:
> >> DMA_PRIVATE here keeps all channels private, so they couldn't be used
> >> elsewhere, for example raid offload.  Do you need a private allocation
> >> or can you get away with a dynamically assigned channel?
> >
> > I would like to have a dedicated DMA engine.  async_tx could cause the
> > copies to complete out of order.  Do I need to add infrastructure to
> > allow for private channel usage, and when unused allow the channel to
> > be used by async_tx?
> 
> Can NTB just call dma_find_channel() once and be done?  Also, async_tx
> will only get things out of order if you allow it to pick a new
> channel for every operation, but as long as you specify a dependency
> chain it will keep things in order (same as remembering the result of
> dma_find_channel).

Neither of these allow a device exclusive access to a channel.  Is
this not something that is desired by other users of DMA Engines, or
do I have a unique usage model?

Thanks,
Jon

> 
> --
> Dan

  reply	other threads:[~2013-06-19 20:11 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
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 [this message]
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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