linux-kernel - Re: [PATCHv6 3/8] dma-mapping: add dma_{map,unmap}

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Message-ID: <20160519112926.GO29375@bigcity.dyn.berto.se>
Date:	Thu, 19 May 2016 13:29:26 +0200
From:	"Niklas Söderlund" <niklas.soderlund@...natech.se>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	vinod.koul@...el.com, linux-renesas-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	dmaengine@...r.kernel.org, iommu@...ts.linux-foundation.org,
	hch@...radead.org, linux-arch@...r.kernel.org,
	geert+renesas@...der.be, arnd@...db.de, linus.walleij@...aro.org,
	laurent.pinchart@...asonboard.com, dan.j.williams@...el.com
Subject: Re: [PATCHv6 3/8] dma-mapping: add dma_{map,unmap}_resource

Hi Konrad,

Thanks for your feedback.

On 2016-05-17 10:54:45 -0400, Konrad Rzeszutek Wilk wrote:
> >  
> > -In some circumstances dma_map_single() and dma_map_page() will fail to create
> > -a mapping. A driver can check for these errors by testing the returned
> > -DMA address with dma_mapping_error(). A non-zero return value means the mapping
> > -could not be created and the driver should take appropriate action (e.g.
> > -reduce current DMA mapping usage or delay and try again later).
> > +In some circumstances dma_map_single(), dma_map_page() and dma_map_resource()
> > +will fail to create a mapping. A driver can check for these errors by testing
> > +the returned DMA address with dma_mapping_error(). A non-zero return value
> > +means the mapping could not be created and the driver should take appropriate
> > +action (e.g. reduce current DMA mapping usage or delay and try again later).
> 
> This looks like it belongs to another patch?

No it is correct (at least intended to be in this patch). All it really 
do is inject dma_map_resource() (which is added in this patch) as one of 
the calls which return dma_addr_t should be checked for error using 
dma_mapping_error().  But yes the change effect all lines in the 
paragraph due to line wrapping.

Hum or maybe I'm misunderstanding your question.

-- 
Regards,
Niklas Söderlund