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Date: Mon, 23 Apr 2012 10:50:13 +0100
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Boojin Kim <boojin.kim@samsung.com>
Subject: Re: [PATCH 5/9] dmaengine: provide a common function for
 completing a dma descriptor
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On Mon, Apr 23, 2012 at 06:40:06PM +0900, Boojin Kim wrote:
> I met a problem on DMA cyclic mode (DMA_CYCLIC) for sound playback.
> Kernel BUG occurs during DMA transfer with DMA cyclic mode.
> This patch makes the cookies into zero. But, cookies should be kept
> during cyclic mode because cyclic mode re-uses the cookies.

The protection is there to prevent cookies being accidentally re-used.
If you're running a cyclic transfer, even then you shouldn't be completing
the same cookie time and time again - I think Vinod also concurs with this.

I think our preference is for cyclic transfers to entire remain uncompleted,
or to get a new cookie each time they allegedly "complete".