On Fri, 2009-07-31 at 20:41 +0100, David Woodhouse wrote:
> On an iMac G5, the b43 driver is failing to initialise because trying to
> set the dma mask to 30-bit fails. Even though there's only 512MiB of RAM
> in the machine anyway:
> https://bugzilla.redhat.com/show_bug.cgi?id=514787
>
> We should probably let it succeed if the available RAM in the system
> doesn't exceed the requested limit.
>
> Signed-off-by: David Woodhouse <david.woodho...@intel.com>
Also, isn't our iommu code smart enough to clamp allocations to the DMA
mask nowadays ? In that case, we could probably just force iommu on
always...
Cheers,
Ben.
> diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
> index 20a60d6..1769a8e 100644
> --- a/arch/powerpc/kernel/dma.c
> +++ b/arch/powerpc/kernel/dma.c
> @@ -90,11 +90,11 @@ static void dma_direct_unmap_sg(struct device *dev,
> struct scatterlist *sg,
> static int dma_direct_dma_supported(struct device *dev, u64 mask)
> {
> #ifdef CONFIG_PPC64
> - /* Could be improved to check for memory though it better be
> - * done via some global so platforms can set the limit in case
> + extern unsigned long highest_memmap_pfn;
> + /* Could be improved so platforms can set the limit in case
> * they have limited DMA windows
> */
> - return mask >= DMA_BIT_MASK(32);
> + return (mask >> PAGE_SHIFT) >= highest_memmap_pfn;
> #else
> return 1;
> #endif
>
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