Subject: Re: [PATCH 14/15] ppc64 iommu: use coherent_dma_mask for alloc_coherent

From: Benjamin Herrenschmidt <[email-masked]>
Date: Mon, 29 Nov 2010 11:58:16 +1100

On Wed, 2010-09-15 at 11:05 -0700, Nishanth Aravamudan wrote:
> The IOMMU code has been passing the dma-mask instead of the
> coherent_dma_mask to the iommu allocator.  Coherent allocations should
> be made using the coherent_dma_mask.

Won't that break macio devices too ? afaik, they don't set
coherent_dma_mask. Have you tried booting on a G5 with iommu enabled ?

(It may not be broken, just asking...)

Cheers,
Ben.

> Signed-off-by: Milton Miller <[email-masked]>
> Signed-off-by: Nishanth Aravamudan <[email-masked]>
> ---
> We currently don't check the mask other than to warn when its being set,
> so I don't think this is stable material.
> ---
>  arch/powerpc/kernel/dma-iommu.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
> index 6e54a0f..e755415 100644
> --- a/arch/powerpc/kernel/dma-iommu.c
> +++ b/arch/powerpc/kernel/dma-iommu.c
> @@ -19,7 +19,7 @@ static void *dma_iommu_alloc_coherent(struct device *dev, size_t size,
>  				      dma_addr_t *dma_handle, gfp_t flag)
>  {
>  	return iommu_alloc_coherent(dev, get_iommu_table_base(dev), size,
> -				    dma_handle, device_to_mask(dev), flag,
> +				    dma_handle, dev->coherent_dma_mask, flag,
>  				    dev_to_node(dev));
>  }
>