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From: Lars-Peter Clausen <lars@metafoo.de>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
	Vinod Koul <vinod.koul@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] dmaengine: care sd_dma_address/len in dmaengine_prep_slave_single()
Date: Wed, 25 Apr 2012 16:18:23 +0200	[thread overview]
Message-ID: <4F9807AF.3000804@metafoo.de> (raw)
In-Reply-To: <20120201182201.GE889@n2100.arm.linux.org.uk>

On 02/01/2012 07:22 PM, Russell King - ARM Linux wrote:
> On Mon, Jan 30, 2012 at 05:13:30PM -0800, Kuninori Morimoto wrote:
>> +	sg_init_table(&sg, 1);
>> +	sg_set_page(&sg, pfn_to_page(PFN_DOWN(buf)),
>> +		    len, offset_in_page(buf));
> 
> There's not much point setting this - the page/virtual address should
> not be used by DMA engines as that may not reflect what's being requested
> (especially if there's an IOMMU in the way.)

I was just looking at this again and there are actually quite a few dma
engine drivers which use sg->length and sg_phys(sg). I guess these would
break if the sg_set_page was to be removed. Should these drivers be changed
to use sg_dma_len and sg_dma_address?

Thanks
- Lars

  reply	other threads:[~2012-04-25 14:15 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-30  9:25 [PATCH] dmaengine: care sd_dma_address/len in dmaengine_prep_slave_single() Kuninori Morimoto
2012-01-30  9:56 ` Vinod Koul
2012-01-31  1:13   ` [PATCH v2] " Kuninori Morimoto
2012-02-01 18:22     ` Russell King - ARM Linux
2012-04-25 14:18       ` Lars-Peter Clausen [this message]
2012-04-25 14:29         ` Russell King - ARM Linux
2012-03-08  9:48     ` Lars-Peter Clausen
2012-03-09  0:18       ` Kuninori Morimoto
2012-03-10 11:12         ` Lars-Peter Clausen
2012-03-13  0:46           ` Kuninori Morimoto

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