[PATCH dma-mapping tree] arm64: default to the direct mapping in get_arch_dma_ops

[Robin Murphy]

On 14/12/2018 15:02, Christoph Hellwig wrote:
> Otherwise the direct mapping won't work at all given that a NULL
> dev->dma_ops causes a fallback.  Note that we already explicitly set
> dev->dma_ops to dma_dummy_ops for dma-incapable devices, so this
> fallback should not be needed anyway.

Sorry, I'd somehow completely missed that you'd sent a proper patch for 
this - indeed it looks like the right change to make.

Reviewed-by: Robin Murphy <robin.murphy at arm.com>

> Fixes: 356da6d0cd ("dma-mapping: bypass indirect calls for dma-direct")
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> Reported-by: Marek Szyprowski <m.szyprowski at samsung.com>
> Tested-by: Marek Szyprowski <m.szyprowski at samsung.com>
> ---
>   arch/arm64/include/asm/dma-mapping.h | 6 +-----
>   1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/dma-mapping.h b/arch/arm64/include/asm/dma-mapping.h
> index 273e778f7de2..95dbf3ef735a 100644
> --- a/arch/arm64/include/asm/dma-mapping.h
> +++ b/arch/arm64/include/asm/dma-mapping.h
> @@ -26,11 +26,7 @@
>   
>   static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
>   {
> -	/*
> -	 * We expect no ISA devices, and all other DMA masters are expected to
> -	 * have someone call arch_setup_dma_ops at device creation time.
> -	 */
> -	return &dma_dummy_ops;
> +	return NULL;
>   }
>   
>   void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
>