Re: [PATCH] ALSA: pcm_dmaengine: correct the error handler of dmaengine_prep_dma_cyclic

[Barry Song <21cnbao@gmail.com>]

2014-12-25 17:02 GMT+08:00 Lars-Peter Clausen <lars@metafoo.de>:
> 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.

i think it is something wrong. an functions returns pointer should return one of
(1) right pointer
(2) NULL
(3) a wrong pointer from error CODES

if for 2&3, we both return NULL, it actually means we are taking
something wrong.

this should be a generic rule as from clk and other subsystems. why
does DMA want to do something special?

>
> - Lars
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-barry