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Date: Wed, 27 Jun 2007 00:38:41 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Jeff Garzik <jeff@garzik.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, linux-ide@vger.kernel.org,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [git patches] libata fixes
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On Wed, 27 Jun 2007 03:35:26 -0400 Jeff Garzik <jeff@garzik.org> wrote:

> +	/* Don't allow DMA if it isn't multiple of 16 bytes.  Quite a
> +	 * few ATAPI devices choke on such DMA requests.
> +	 */
> +	if (unlikely(qc->nbytes & 15))
> +		return 1;

It might be worth emitting a diagnostic when this happens.