Re: IB: Add DMA mapping functions to allow device drivers to interpose

[Andrew Morton <akpm@osdl.org>]

On Wed, 13 Dec 2006 03:59:45 GMT
Linux Kernel Mailing List <linux-kernel@vger.kernel.org> wrote:

>     IB: Add DMA mapping functions to allow device drivers to interpose
>     
>     The QLogic InfiniPath HCAs use programmed I/O instead of HW DMA.
>     This patch allows a verbs device driver to interpose on DMA mapping
>     function calls in order to avoid relying on bus_to_virt() and
>     phys_to_virt() to undo the mappings created by dma_map_single(),
>     dma_map_sg(), etc.
>     
>     Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
>     Signed-off-by: Roland Dreier <rolandd@cisco.com>

include/rdma/ib_verbs.h: In function 'ib_dma_alloc_coherent':
include/rdma/ib_verbs.h:1635: warning: passing argument 3 of 'dma_alloc_coherent' from incompatible pointer type
In file included from drivers/infiniband/hw/mthca/mthca_provider.h:41,
                 from drivers/infiniband/hw/mthca/mthca_dev.h:53,
                 from drivers/infiniband/hw/mthca/mthca_main.c:44:
include/rdma/ib_verbs.h: In function 'ib_dma_alloc_coherent':
include/rdma/ib_verbs.h:1635: warning: passing argument 3 of 'dma_alloc_coherent' from incompatible pointer type


That u64 needs to become a dma_addr_t.  That means that
ib_dma_mapping_ops.alloc_coherent() and ib_dma_mapping_ops.free_coherent() are
wrong as well.

> +struct ib_dma_mapping_ops {
> ...
> +	void		*(*alloc_coherent)(struct ib_device *dev,
> +					   size_t size,
> +					   u64 *dma_handle,
> +					   gfp_t flag);
> +	void		(*free_coherent)(struct ib_device *dev,
> +					 size_t size, void *cpu_addr,
> +					 u64 dma_handle);
> +};

I'd have picked this up if it had been in git-infiniband for even a couple
of days.  I'm assuming this all got slammed into mainline because of the
merge window thing.

I cannot find these patches on the kernel mailing list.  I cannot find the
pull request anywhere.

> +static inline u64 ib_dma_map_single(struct ib_device *dev,
> +				    void *cpu_addr, size_t size,
> +				    enum dma_data_direction direction)

no, dma_map_single() returns a dma_addr_t.