From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Wed, 30 Mar 2016 20:18:31 +0200
From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Mark Brown <broonie@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>, Brian Norris
 <computersforpeace@gmail.com>, linux-mtd@lists.infradead.org, Andrew Morton
 <akpm@linux-foundation.org>, Dave Gordon <david.s.gordon@intel.com>,
 linux-spi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Maxime
 Ripard <maxime.ripard@free-electrons.com>, Chen-Yu Tsai <wens@csie.org>,
 linux-sunxi@googlegroups.com, Vinod Koul <vinod.koul@intel.com>, Dan
 Williams <dan.j.williams@intel.com>, dmaengine@vger.kernel.org, Mauro
 Carvalho Chehab <m.chehab@samsung.com>, Hans Verkuil
 <hans.verkuil@cisco.com>, Laurent Pinchart
 <laurent.pinchart@ideasonboard.com>, linux-media@vger.kernel.org, Rob
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 Gala <galak@codeaurora.org>, devicetree@vger.kernel.org, Richard Weinberger
 <richard@nod.at>
Subject: Re: [PATCH v2 4/7] scatterlist: add sg_alloc_table_from_buf() helper
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On Wed, 30 Mar 2016 09:51:43 -0700
Mark Brown <broonie@kernel.org> wrote:

> On Wed, Mar 30, 2016 at 05:39:51PM +0200, Boris Brezillon wrote:
> > sg_alloc_table_from_buf() provides an easy solution to create an sg_table
> > from a virtual address pointer. This function takes care of dealing with
> > vmallocated buffers, buffer alignment, or DMA engine limitations (maximum
> > DMA transfer size).
> 
> This seems nice.  Should we also have a further helper on top of this
> which will get constraints from a dmaengine, it seems like it'd be a
> common need?

Yep, we could create a wrapper extracting dma_slave caps info,
converting it to sg_constraints and calling sg_alloc_table_from_buf().
But let's try to get this function accepted first, and I'll send another
patch providing this wrapper.

BTW, do you see other things that should be added in sg_constraints?

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com