Re: How to map high memory for block io

[Russell King <rmk+lkml@arm.linux.org.uk>]

On Thu, Mar 02, 2006 at 11:26:13AM +0100, Pierre Ossman wrote:
> This I know. My beef is the readability of:
> 
> if (do_dma)
>     *dev->dma_mask = DEVICE_DMA_MASK;
> else
>     *dev->dma_mask = 0;
> 
> I.e. we use dma_mask even though we don't do DMA.

Not a lot we can do about the readability issue - we end up with code
like that in some layer of the MMC.  If it's in mmc_queue, it might be:

        u64 limit = BLK_BOUNCE_HIGH;

        if (host->caps & MMC_CAP_DMA &&
	    host->dev->dma_mask && *host->dev->dma_mask)
                limit = *host->dev->dma_mask;

which is equally as (un)readable as your code.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core