linux-kernel - Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}

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Message-ID: <20160425142619.GJ28777@bigcity.dyn.berto.se>
Date:	Mon, 25 Apr 2016 16:26:19 +0200
From:	Niklas Söderlund <niso@....se>
To:	Christoph Hellwig <hch@...radead.org>
Cc:	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Vinod Koul <vinod.koul@...el.com>,
	linux-renesas-soc@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
	iommu@...ts.linux-foundation.org, robin.murphy@....com,
	geert+renesas@...der.be, Linus Walleij <linus.walleij@...aro.org>,
	Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org
Subject: Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource

Hi Christoph,

On 2016-04-21 06:49:42 -0700, Christoph Hellwig wrote:
> On Wed, Apr 13, 2016 at 03:29:17PM +0200, Niklas S?derlund wrote:
> > > Yes, it would be good to do an audit of all the ARM dma_ops as well
> > > as generic code like drivers/base/dma-*.c, lib/dma-debug.c and
> > > include/linux/dma-*.h
> 
> What about things like the phys_addr() helper in lib/dma-debug.c?  That
> was in fact what prompted my question for an audit, and it seems
> to not even feature on your list.  What patterns / symbols did you look
> for?


I have followed the call path from the usage in 
drivers/dma/sh/rcar-dmac.c and made sure the dma_addr_t is not used in a 
bad way.

I also looked at the dma-mapping API and ruled out that the only 
function that make sens to use with a dma_addr_t from dma_map_resource() 
are dma_unmap_resource() and dma_mapping_error(). With that I can't see 
how a dma_addr_t would end up in lib/dma-debug.c. But I might be missing 
something?

In the big picture do you feel the approach I have is the correct way to 
solve my problem? Provided we can work out this issues ofc?

-- 
Regards,
Niklas Söderlund