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Subject: Re: [PATCH v2 5/5] libnvdimm: add DMA support for pmem blk-mq
References: <150169902310.59677.18062301799811367806.stgit@djiang5-desk3.ch.intel.com>
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From: Dave Jiang <dave.jiang@intel.com>
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Date: Wed, 2 Aug 2017 13:52:46 -0700
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To: Sinan Kaya <okaya@codeaurora.org>, "Koul, Vinod" <vinod.koul@intel.com>, "Williams, Dan J" <dan.j.williams@intel.com>
Cc: "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>, "linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>
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On 08/02/2017 12:22 PM, Sinan Kaya wrote:
> On 8/2/2017 2:41 PM, Dave Jiang wrote:
>>  	if (queue_mode == PMEM_Q_MQ) {
>> +		chan = dma_find_channel(DMA_MEMCPY);
>> +		if (!chan) {
>> +			queue_mode = PMEM_Q_BIO;
>> +			dev_warn(dev, "Forced back to PMEM_Q_BIO, no DMA\n");
>> +		}
> 
> We can't expect all MEMCPY capable hardware to support this feature, right?
> 
> Do we need a new API / new function, or new capability?

Hmmm...you are right. I wonder if we need something like DMA_SG cap....


> 
>> +	}
> 
> 
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