[PATCH v1 09/17] docs: core-api: document the IOVA-based API

[Leon Romanovsky]

On Fri, Nov 08, 2024 at 12:34:21PM -0700, Jonathan Corbet wrote:
> Leon Romanovsky <leon at kernel.org> writes:
> 
> > From: Christoph Hellwig <hch at lst.de>
> >
> > Add an explanation of the newly added IOVA-based mapping API.
> >
> > Signed-off-by: Christoph Hellwig <hch at lst.de>
> > Signed-off-by: Leon Romanovsky <leonro at nvidia.com>
> > ---
> >  Documentation/core-api/dma-api.rst | 70 ++++++++++++++++++++++++++++++
> >  1 file changed, 70 insertions(+)
> >
> > diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/dma-api.rst
> > index 8e3cce3d0a23..6095696a65a7 100644
> > --- a/Documentation/core-api/dma-api.rst
> > +++ b/Documentation/core-api/dma-api.rst
> > @@ -530,6 +530,76 @@ routines, e.g.:::
> >  		....
> >  	}
> >  
> > +Part Ie - IOVA-based DMA mappings
> > +---------------------------------
> > +
> > +These APIs allow a very efficient mapping when using an IOMMU.  They are an
> > +optional path that requires extra code and are only recommended for drivers
> > +where DMA mapping performance, or the space usage for storing the DMA addresses
> > +matter.  All the consideration from the previous section apply here as well.
> > +
> > +::
> > +
> > +    bool dma_iova_try_alloc(struct device *dev, struct dma_iova_state *state,
> > +		phys_addr_t phys, size_t size);
> > +
> > +Is used to try to allocate IOVA space for mapping operation.  If it returns
> > +false this API can't be used for the given device and the normal streaming
> > +DMA mapping API should be used.  The ``struct dma_iova_state`` is allocated
> > +by the driver and must be kept around until unmap time.
> 
> So, I see that you have nice kernel-doc comments for these; why not just
> pull them in here with a kernel-doc directive rather than duplicating
> the information?

Can I you please point me to commit/lore link/documentation with example
of such directive and I will do it?

Thanks

> 
> Thanks,
> 
> jon