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Message-ID: <402D3244.6020402@pacbell.net>
Date: Fri, 13 Feb 2004 12:23:32 -0800
From: David Brownell <david-b@pacbell.net>
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To: Geert Uytterhoeven <geert@linux-m68k.org>
CC: linux-kernel@vger.kernel.org
Subject: Re: dmapool (was: Re: Linux 2.6.3-rc2)
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> +static inline int
> +dma_supported(struct device *dev, u64 mask)
> +{
> +	BUG();
> +	return 0;
> +}

dma_supported() in particular shouldn't BUG(); this should work:

    if (use_dma && dma_supported(dev, ~(u32)0)) {
        ... set up for DMA ...
    } else {
        ... just use PIO instead ...
    }

Likewise the other routines that have clearly defined fault paths
should probably just use those instead of BUG().  Examples of this
type would be dma_alloc_coherent(), dma_map_sg() and maybe also
dma_get_cache_alignment().


Of course the API still lacks clean fault reporting for the single
shot mapping calls -- like maybe an arch-settable

   #define DMA_ADDR_INVALID (~(dma_addr_t)0)

return value -- but that'd be a different patch.

- Dave