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

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Message-ID: <20160519142248.GB21691@localhost.localdomain>
Date:	Thu, 19 May 2016 10:22:48 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	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

On Thu, May 19, 2016 at 01:29:26PM +0200, Niklas Söderlund wrote:
> 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.

I totally missed the 'dma_map_resource' in there and just read
'dma_mapping_error'!

<sigh> Thanks.
> 
> -- 
> Regards,
> Niklas Söderlund