Re: [PATCH 5/9] dmaengine: provide a common function for completing a dma descriptor

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".