Re: [PATCH 02/20] dma-mapping: provide a generic dma-noncoherent implementation

[Helge Deller]

On 18.05.2018 15:03, Alexey Brodkin wrote:
> But the real fix of my problem is:
> ---------------------------------------->8------------------------------------
> --- a/lib/dma-noncoherent.c
> +++ b/lib/dma-noncoherent.c
> @@ -35,7 +35,7 @@ static dma_addr_t dma_noncoherent_map_page(struct device *dev, struct page *page
>  
>         addr = dma_direct_map_page(dev, page, offset, size, dir, attrs);
>         if (!dma_mapping_error(dev, addr) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
> -               arch_sync_dma_for_device(dev, page_to_phys(page), size, dir);
> +               arch_sync_dma_for_device(dev, page_to_phys(page) + offset, size, dir);
>         return addr;
>  }
> ---------------------------------------->8------------------------------------
> 
> You seem to lost an offset in the page so if we happen to have a buffer not aligned to
> a page boundary then we were obviously corrupting data outside our data :)

Good.
This patch seems to fix the dma issues I faced on my 32bit B160L parisc box.

So it leaves only one open issue on parisc:
Now every 32 bit parisc system is unnecessarily non-coherent.

Helge
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