[PATCH 1/2] [usb] make xhci platform driver use 64 bit or 32 bit DMA

[arnd@arndb.de (Arnd Bergmann)]

On Thursday 30 October 2014 13:16:28 Mark Langsdorf wrote:
> -       /* Initialize dma_mask and coherent_dma_mask to 32-bits */
> -       ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
> -       if (ret)
> -               return ret;
> +       /* Try setting the coherent_dma_mask to 64 bits, then try 32 bits */
> +       if (sizeof(dma_addr_t) < 8 ||
> +               dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64))) {
> +               ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
> +               if (ret)
> +                       return ret;
> +       }
>         if (!pdev->dev.dma_mask)
>                 pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
>         else
> -               dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
> +               dma_set_mask(&pdev->dev, pdev->dev.coherent_dma_mask);
>  
>         hcd = usb_create_hcd(driver, &pdev->dev, dev_name(&pdev->dev));
>         if (!hcd)
> 

The logic here seems wrong: if dma_set_mask is successful, you
can rely on on dma_set_coherent_mask suceeding as well, but
not the other way round.

Also, we should no longer need to worry about the case where
pdev->dev.dma_mask is NULL, as this now gets initialized from
the DT setup.

	Arnd