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

Konrad Rzeszutek Wilk konrad.wilk at oracle.com
Thu May 19 07:22:48 PDT 2016


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



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