Re: [PATCH] dma-buf: add dma_data_direction to unmap dma_buf_op

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Jan 31, 2012 at 10:42:59AM +0100, Laurent Pinchart wrote:
> Hi Sumit,
> 
> > On Friday 27 January 2012 10:43:28 Sumit Semwal wrote:
> 
> [snip]
> 
> >  static inline void dma_buf_unmap_attachment(struct dma_buf_attachment
> > *attach,
> > -                                            struct sg_table *sg)
> > +                     struct sg_table *sg, enum dma_data_direction write)
> 
> On a second thought, would it make sense to store the direction in struct 
> dma_buf_attachment in dma_buf_map_attachment(), and pass the value directly to 
> the .unmap_dma_buf() instead of requiring the dma_buf_unmap_attachment() 
> caller to remember it ? Or is an attachment allowed to map the buffer several 
> times with different directions ?

Current dma api functions already require you to supply the direction
argument on unmap and I think for cpu access I'm also leaning towards an
interface where the importer has to supply the direction argument for both
begin_access and end_access. So for consistency reasons I'm leaning
towards adding it to unmap.
-Daniel
-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48