From: vinod.koul@intel.com (Vinod Koul)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] dmaengine: qcom_hidma: release the descriptor before the callback
Date: Wed, 10 Aug 2016 22:58:05 +0530 [thread overview]
Message-ID: <20160810172805.GH9681@localhost> (raw)
In-Reply-To: <21475c6e-a5f8-5125-3998-f3995ce67c4d@codeaurora.org>
On Mon, Aug 08, 2016 at 10:45:24AM -0400, Sinan Kaya wrote:
> On 8/8/2016 5:02 AM, Vinod Koul wrote:
> >> What Vinod is telling me that I need to set the cookie to complete
> >> > whether the transaction is successful or not if the request was accepted
> >> > by HW. xyz_tx_status is just an indication that the transaction was accepted
> >> > by HW. An error can happen as a result of transaction execution.
> > Nope, if the txn is completed you mark it complete. If you can detect error
> > (can you??) then you can report DMA_ERROR.
> >
>
> Yes, the HW reports if a transaction failed or not. I have this information
> available in hidma_ll_status function for a limited amount of time until the
> descriptor gets reused.
>
> > In that latter case do not use dma_async_is_complete() to check. You would
> > need to store and report that cookie 'x' failed which you report status in
> > .tx_statis()
> >
>
> I really don't like the idea of telling 'hey client I finished your work and I
> guarantee you it is complete. A month from now, by the way I actually didn't do
> the work that day and I did not tell you'
As i said previously, controllers cannot detect errors. In a system DMA burst
may go bad due to various different issues which controller has not handle
over. So from s system PoV we cannot declare success!
> That's why, I preferred not to call the callback when I observe an error which I
> think it makes more sense.
That doesnt make sense. A client set a callback, it expect you to call one.
The result quried maybe txn completed or error. Since you have means, please
report..
> Where is the reliability in this? Some random bugs showing at random times.
> I'd rather not call the callback and be safe. Especially, if you are talking about
> servers; this is plain unacceptable.
How does ignoring client wish caller solve this? You are really ona wrong
path here.
> As Lars-Peter and I indicated in my last email, I think we need to kill this
> tx_status API and replace all the clients to use Dave's interface. It is practically
> impossible to implement a reliable tx_status function.
>
> Once this transition happens, I can implement Dave's interface not before.
>
> Again, it will be a different patch than this one. I think v2 of this patch
> needs to go in as it is.
>
> https://lkml.org/lkml/2016/7/31/64
I havent looked at the patch. If it is not invoking callback set by user,
then I am not taking it. Sorry, we dont choose over client's wish.
Thanks
--
~Vinod
next prev parent reply other threads:[~2016-08-10 17:28 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-14 2:57 [PATCH] dmaengine: qcom_hidma: release the descriptor before the callback Sinan Kaya
2016-07-16 1:00 ` Sinan Kaya
2016-07-24 6:24 ` Vinod Koul
2016-07-25 14:19 ` Sinan Kaya
2016-08-04 12:55 ` Vinod Koul
2016-08-04 14:17 ` Sinan Kaya
2016-08-04 14:40 ` Russell King - ARM Linux
2016-08-04 15:27 ` Sinan Kaya
2016-08-04 15:38 ` Russell King - ARM Linux
2016-08-04 15:59 ` Lars-Peter Clausen
2016-08-08 9:08 ` Vinod Koul
2016-08-08 12:25 ` Lars-Peter Clausen
2016-08-10 17:23 ` Vinod Koul
2016-08-04 16:08 ` Sinan Kaya
2016-08-04 16:15 ` Lars-Peter Clausen
2016-08-05 6:32 ` Robert Jarzmik
2016-08-05 8:34 ` Lars-Peter Clausen
2016-08-05 15:17 ` Sinan Kaya
2016-08-08 9:02 ` Vinod Koul
2016-08-08 14:45 ` Sinan Kaya
2016-08-10 17:28 ` Vinod Koul [this message]
2016-08-10 17:31 ` Sinan Kaya
2016-08-19 2:48 ` Vinod Koul
2016-08-19 3:26 ` Sinan Kaya
2016-08-19 3:42 ` Vinod Koul
2016-08-19 3:48 ` Sinan Kaya
2016-08-19 5:52 ` Vinod Koul
2016-08-19 11:13 ` okaya at codeaurora.org
2016-08-19 17:02 ` Vinod Koul
2016-08-19 17:21 ` Sinan Kaya
2016-08-22 6:08 ` Vinod Koul
2016-08-22 13:27 ` Sinan Kaya
2016-08-22 17:00 ` Vinod Koul
2016-08-08 8:51 ` Vinod Koul
2016-08-08 12:10 ` okaya at codeaurora.org
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