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