[PATCH] DMA: extend documentation to provide more API details

[swarren@wwwdotorg.org (Stephen Warren)]

On 10/08/2013 07:34 PM, Dan Williams wrote:
> On Mon, Oct 7, 2013 at 3:39 AM, Vinod Koul <vinod.koul@intel.com> wrote:
>> On Mon, Oct 07, 2013 at 12:17:28PM +0100, Russell King - ARM Linux wrote:
...
>>> What may be better is to change the wording here: not DMA_SUCCESS but
>>> DMA_COMPLETED.  That doesn't imply that it has been successful, merely
>>> that the DMA engine has finished with the transaction.
>>
>> Agreed that its not indication of success but of DMA completetion. I have seen
>> cases where slave perhiphral got stuck while sending last FIFO but since DMA
>> finished transferiing to FIFO it says complete.

In that case, the DMA *has* completed. DMA is the transfer into the
FIFO, not the handling of the FIFO content by the peripheral.

>> Dan do you agree?
> 
> Yes, it's an indication of completion, not necessarily success.

Surely by definition, a DMA can't *complete* without being successful.
If the DMA failed, then it didn't complete, but rather must have been
aborted or error'd out, without completing the whole transfer.