Re: [PATCH v2] of: Set the DMA mask to 64 bits when dma_addr_t is 64-bits

[Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 04/26/2013 01:06 PM, Laura Abbott wrote:
> Currently, of_platform_device_create_pdata always sets the
> coherent DMA mask to 32 bits. On ARM systems without CONFIG_ZONE_DMA,
> arm_dma_limit gets set to ~0 or 0xFFFFFFFFFFFFFFFF on LPAE based
> systems. Since arm_dma_limit represents the smallest dma_mask
> on the system, the default of 32 bits prevents any dma_coherent
> allocation from succeeding unless clients manually set the
> dma mask first. Rather than make every client on an LPAE system set
> the mask, set the mask to a 64 bit value on systems with 64-bit
> dma addresses.
> 
> Signed-off-by: Laura Abbott <lauraa-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> ---
>  drivers/of/platform.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 0970505..c669ab4 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -214,7 +214,11 @@ struct platform_device *of_platform_device_create_pdata(
>  #if defined(CONFIG_MICROBLAZE)
>  	dev->archdata.dma_mask = 0xffffffffUL;
>  #endif
> +#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
> +	dev->dev.coherent_dma_mask = DMA_BIT_MASK(64);
> +#else
>  	dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
> +#endif

How about "DMA_BIT_MASK(sizeof(dma_addr_t) * 8))" and avoid the ifdef.

Rob