linux-kernel - Re: [PATCH 5/7] mtd: provide helper to prepare buffers for DMA operations

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Date:	Tue, 8 Mar 2016 15:46:20 +0100
From:	Boris Brezillon <boris.brezillon@...e-electrons.com>
To:	Vinod Koul <vinod.koul@...el.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Gordon <david.s.gordon@...el.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>,
	linux-mtd@...ts.infradead.org, Mark Brown <broonie@...nel.org>,
	linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Chen-Yu Tsai <wens@...e.org>, linux-sunxi@...glegroups.com,
	Dan Williams <dan.j.williams@...el.com>,
	dmaengine@...r.kernel.org,
	Mauro Carvalho Chehab <m.chehab@...sung.com>,
	Hans Verkuil <hans.verkuil@...co.com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	linux-media@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>, devicetree@...r.kernel.org
Subject: Re: [PATCH 5/7] mtd: provide helper to prepare buffers for DMA
 operations

On Tue, 8 Mar 2016 19:48:53 +0530
Vinod Koul <vinod.koul@...el.com> wrote:

> On Tue, Mar 08, 2016 at 12:15:13PM +0100, Boris Brezillon wrote:
> >  
> > +#ifdef CONFIG_HAS_DMA
> 
> Shouldn't this be CONFIG_DMA_ENGINE as you are preparing these descriptors
> for DMA transfer?
> 

Nope, scatterlist users are not necessarily using a dmaengine, some IPs
are directly embedding a dedicated DMA engine, which has no driver in
drivers/dma/.

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