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Date:   Wed, 11 Mar 2020 08:28:38 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Christian =?iso-8859-1?Q?K=F6nig?= 
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Subject: Re: [PATCH 1/6] lib/scatterlist: add sg_set_dma_addr() function
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On Wed, Mar 11, 2020 at 02:51:53PM +0100, Christian König wrote:
> This can be used by drivers to setup P2P DMA between device
> memory which is not backed by struct pages.
> 
> The drivers of the involved devices are responsible for
> setting up and tearing down DMA addresses as necessary
> using dma_map_resource().
> 
> The page pointer is set to NULL and only the DMA address,
> length and offset values are valid.

NAK.  The only valid way to fill DMA address in scatterlists is
dma_map_sg / dma_map_sg_attr.