From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] DMA: extend documentation to provide more API details
Date: Thu, 17 Oct 2013 08:55:41 -0600 [thread overview]
Message-ID: <525FFA6D.8080806@wwwdotorg.org> (raw)
In-Reply-To: <20131017051636.GB14013@intel.com>
On 10/16/2013 11:16 PM, Vinod Koul wrote:
> On Wed, Oct 16, 2013 at 01:33:44PM -0600, Stephen Warren wrote:
>> 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.
>
> DMA means transferring of data, and that is what DMA compeletion would mean.
> Once the data has left the DMA FIFO, we don't know if it filled up the memory
> propery or get stuck in periphral FIFO, the dmaengine would have no knowledge or
> control of it. So it can't claim the transfer was success from a data point of
> view, hence the rename now!
Well, I obviously don't agreee, but I guess I won't bother pursuing this.
next prev parent reply other threads:[~2013-10-17 14:55 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-05 17:36 [PATCH] DMA: extend documentation to provide more API details Guennadi Liakhovetski
2013-10-05 19:02 ` Russell King - ARM Linux
2013-10-05 21:00 ` Guennadi Liakhovetski
2013-10-05 23:31 ` Russell King - ARM Linux
2013-10-06 5:20 ` Vinod Koul
2013-10-07 10:45 ` Guennadi Liakhovetski
2013-10-07 10:41 ` Vinod Koul
2013-10-07 12:17 ` Guennadi Liakhovetski
2013-10-07 11:17 ` Russell King - ARM Linux
2013-10-07 10:39 ` Vinod Koul
2013-10-07 12:15 ` Guennadi Liakhovetski
2013-10-07 14:25 ` Vinod Koul
2013-10-07 15:28 ` Guennadi Liakhovetski
2013-10-07 14:43 ` Vinod Koul
2013-10-07 15:45 ` Guennadi Liakhovetski
2013-10-07 15:52 ` Vinod Koul
2013-10-07 20:55 ` Guennadi Liakhovetski
2013-10-08 3:52 ` Vinod Koul
2013-10-08 7:28 ` Guennadi Liakhovetski
2013-10-07 15:48 ` Vinod Koul
2013-10-07 20:43 ` Guennadi Liakhovetski
2013-10-08 3:58 ` Vinod Koul
2013-10-08 7:17 ` Guennadi Liakhovetski
2013-10-09 1:34 ` Dan Williams
2013-10-10 16:15 ` Vinod Koul
2013-10-16 19:33 ` Stephen Warren
2013-10-17 5:16 ` Vinod Koul
2013-10-17 14:55 ` Stephen Warren [this message]
2013-10-17 17:00 ` Dan Williams
2013-10-07 7:40 ` Guennadi Liakhovetski
2013-10-09 1:28 ` Dan Williams
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