Re: [PATCH 1/3] dmaengine: add new dma API for max_segment_number

[Koul, Vinod]

On Sun, 2011-06-05 at 10:30 +0900, FUJITA Tomonori wrote:
> On Wed, 1 Jun 2011 10:33:57 +0800
> Shawn Guo <shawn.guo@xxxxxxxxxxxxx> wrote:
> 
> > On Thu, May 26, 2011 at 02:31:31PM +0800, Shawn Guo wrote:
> > > Like dma_set(get)_max_seg_size for max_segment_size, the patch adds
> > > max_segment_number into device_dma_parameters and creates the
> > > corresponding dmaengine API dma_set(get)_max_seg_number for it.
> > > 
> > > Signed-off-by: Shawn Guo <shawn.guo@xxxxxxxxxx>
> > > ---
> > >  include/linux/device.h      |    1 +
> > >  include/linux/dma-mapping.h |   15 +++++++++++++++
> > >  2 files changed, 16 insertions(+), 0 deletions(-)
> 
> include/linux/dma-mapping.h is for DMA mapping API (please see
> Documentation/DMA-API*.txt).
> 
> What does dma_set(get)_max_seg_size do? And it's related with DMA
> mapping API?
See the other post by author



> 
> 
> > > 
> > > diff --git a/include/linux/device.h b/include/linux/device.h
> > > index c66111a..44cb2528 100644
> > > --- a/include/linux/device.h
> > > +++ b/include/linux/device.h
> > > @@ -487,6 +487,7 @@ struct device_dma_parameters {
> > >  	 * sg limitations.
> > >  	 */
> > >  	unsigned int max_segment_size;
> > > +	unsigned int max_segment_number;
> > >  	unsigned long segment_boundary_mask;
> > >  };
> > >  
> > > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> > > index ba8319a..fd314f4 100644
> > > --- a/include/linux/dma-mapping.h
> > > +++ b/include/linux/dma-mapping.h
> > > @@ -131,6 +131,21 @@ static inline unsigned int dma_set_max_seg_size(struct device *dev,
> > >  		return -EIO;
> > >  }
> > >  
> > > +static inline unsigned int dma_get_max_seg_number(struct device *dev)
> > > +{
> > > +	return dev->dma_parms ? dev->dma_parms->max_segment_number : 1;
> > > +}
> > > +
> > > +static inline unsigned int dma_set_max_seg_number(struct device *dev,
> > > +						  unsigned int number)
> > > +{
> > > +	if (dev->dma_parms) {
> > > +		dev->dma_parms->max_segment_number = number;
> > > +		return 0;
> > > +	} else
> > > +		return -EIO;
> > > +}
> > > +
> > >  static inline unsigned long dma_get_seg_boundary(struct device *dev)
> > >  {
> > >  	return dev->dma_parms ?
> > > -- 
> > > 1.7.4.1
> > 
> > --
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-- 
~Vinod

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