From mboxrd@z Thu Jan  1 00:00:00 1970
From: Lars-Peter Clausen <lars@metafoo.de>
Subject: Re: [PATCH] ALSA: pcm_dmaengine: correct the error
	handler of dmaengine_prep_dma_cyclic
Date: Thu, 25 Dec 2014 10:02:33 +0100
Message-ID: <549BD2A9.505@metafoo.de>
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To: Barry Song <21cnbao@gmail.com>, peter.ujfalusi@ti.com, tiwai@suse.de, broonie@linaro.org
Cc: alsa-devel@alsa-project.org, workgroup.linux@csr.com, Barry Song <Baohua.Song@csr.com>
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On 12/25/2014 05:41 AM, Barry Song wrote:
> From: Barry Song <Baohua.Song@csr.com>
>
> preparing cyclic DMA description can fail either due to DMA desc list
> is full(-ENOMEM), or due to the coming DMA configuration is illegal or
> not supported by the acting DMA hardware(other ERR codes).

According to the API definition this returns either NULL or a valid 
descriptor, so the behavior in pcm_dmaengine is correct. Maybe your 
particular dmaengine driver as a incorrect implementation.

- Lars