# Re: \[PATCH v2 09/11\] dma-direct: turn ARCH\_ZONE\_DMA\_BITS into a variable

- From: Michael Ellerman \<mpe@ellerman.id.au\>
- Date: 2019-08-26 11:33:59 
- List: linux-devicetree
- Page: https://ratatoskr.run/linux-devicetree/2019/08/5698564
- Thread: https://ratatoskr.run/linux-arm-kernel/2019/08/5693292/t.md

```text
Nicolas Saenz Julienne [ref] writes:
> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
> index 0d52f57fca04..73668a21ae78 100644
> --- a/arch/powerpc/include/asm/page.h
> +++ b/arch/powerpc/include/asm/page.h
> @@ -319,13 +319,4 @@ struct vm_area_struct;
>  #endif /* __ASSEMBLY__ */
>  #include <asm/slice.h>
>  
> -/*
> - * Allow 30-bit DMA for very limited Broadcom wifi chips on many powerbooks.

This comment got lost.

> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index 9191a66b3bc5..2a69f87585df 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -237,9 +238,14 @@ void __init paging_init(void)
>  	printk(KERN_DEBUG "Memory hole size: %ldMB\n",
>  	       (long int)((top_of_ram - total_ram) >> 20));
>  
> +	if (IS_ENABLED(CONFIG_PPC32))

Can you please propagate it here?

> +		zone_dma_bits = 30;
> +	else
> +		zone_dma_bits = 31;
> +

cheers
```