Message-ID: <4B733CEE.9030105@codeaurora.org>
Date: Wed, 10 Feb 2010 15:10:38 -0800
From: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
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To: Russell King - ARM Linux <linux@arm.linux.org.uk>
CC: Randy Dunlap <rdunlap@xenotime.net>, linux-arm-kernel@lists.infradead.org,
       linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
       Catalin Marinas <catalin.marinas@arm.com>,
       Abhijeet Dharmapurikar <adharmap@quicinc.com>
Subject: Re: [RFC 0/2] fix dma_map_sg not to do barriers for each buffer
References: <1265834250-29170-1-git-send-email-adharmap@codeaurora.org> <4B7324D3.1000509@xenotime.net> <20100210224030.GC30854@n2100.arm.linux.org.uk>
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Russell King - ARM Linux wrote:
> On Wed, Feb 10, 2010 at 01:27:47PM -0800, Randy Dunlap wrote:
>> On 02/10/10 12:37, adharmap@codeaurora.org wrote:
>>> From: Abhijeet Dharmapurikar <adharmap@quicinc.com>
>>>
>>> Please refer to the post here
>>> http://lkml.org/lkml/2010/1/4/347
>>>
>>> These changes are to introduce barrierless dma_map_area and dma_unmap_area and
>>> use them to map the buffers in the scatterlist. For the last buffer, call
>>> the normal dma_map_area(aka with barriers) effectively executing the barrier
>>> at the end of the operation.
>>>
>>> Note that the barrierless operations are implemented for few arm
>>> architectures only and I would implement for others once these are okayed by the
>>> community.
>> So when you add these interfaces for other architectures, you will also
>> update Documentation/DMA-API.txt,  right??
> 
> Do we need barrier-less interfaces for anything other than the dma_*_sg
> functions?

I think, dma_*_sg are the only ones that could benefit from barrier-less 
interfaces.

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