Re: [PATCH 06/10] swiotlb: use swiotlb_map_page in swiotlb_map_sg_attrs

[Will Deacon <will.deacon@arm.com>]

Hi John,

On Tue, Nov 20, 2018 at 10:25:16AM +0100, Christoph Hellwig wrote:
> On Mon, Nov 19, 2018 at 03:22:13PM -0800, John Stultz wrote:
> > > +               sg->dma_address = dma_addr;
> > >                 sg_dma_len(sg) = sg->length;
> > >         }
> > 
> > I know Robin has already replied with more detailed info, but just to
> > close the loop as I'm finally home, applying this patch didn't seem to
> > help with the IO hangs I'm seeing w/ HiKey960.
> 
> If Robins observation is right this should fix the problem for you:

Please could you give this diff a try and let us know whether the problem
persists with your board?

Thanks,

Will

> diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
> index bd73e7a91410..1833f0c1fba0 100644
> --- a/include/linux/dma-direct.h
> +++ b/include/linux/dma-direct.h
> @@ -5,7 +5,7 @@
>  #include <linux/dma-mapping.h>
>  #include <linux/mem_encrypt.h>
>  
> -#define DIRECT_MAPPING_ERROR		0
> +#define DIRECT_MAPPING_ERROR		(~(dma_addr_t)0x0)
>  
>  #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
>  #include <asm/dma-direct.h>