linux-kernel - Re: [PATCH 01/28] dmaengine: use DMA_COMPLETE for dma completion status

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Message-ID: <Pine.LNX.4.64.1310250813370.6186@axis700.grange>
Date:	Fri, 25 Oct 2013 08:32:12 +0200 (CEST)
From:	Guennadi Liakhovetski <g.liakhovetski@....de>
To:	Vinod Koul <vinod.koul@...el.com>
cc:	Sebastian Andrzej Siewior <sebastian@...akpoint.cc>,
	Dan Williams <dan.j.williams@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-arm-kernel@...ts.infradead.org, linux@....linux.org.uk
Subject: Re: [PATCH 01/28] dmaengine: use DMA_COMPLETE for dma completion
 status

Hi Vinod

On Fri, 25 Oct 2013, Vinod Koul wrote:

> On Thu, Oct 24, 2013 at 11:28:29PM +0200, Guennadi Liakhovetski wrote:
> > Hi Vinod
> > 
> > On Thu, 17 Oct 2013, Vinod Koul wrote:
> > > Yes i missed it in first place update the patch to fix that
> > 
> > Are you planning to post a fixed version of this patch or you just fix it 
> > internally? Would be good to have it posted to be able to ack it and other 
> > relevant patches.
> looks like you missed it... I had posted updated patch [1] in this thread here
> and I posted 29th patch as removal one [2]

No, I didn't miss those, but as Sebastian pointed out and as I commented 
too, also that v2 version wasn't correct, so, a fixed v3 was needed. 
Consider this:

In patch 1 you do:

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 0bc7275..683c380 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -45,16 +45,17 @@ static inline int dma_submit_error(dma_cookie_t cookie)
 
 /**
  * enum dma_status - DMA transaction status
- * @DMA_SUCCESS: transaction completed successfully
+ * @DMA_COMPLETE: transaction completed
  * @DMA_IN_PROGRESS: transaction not yet processed
  * @DMA_PAUSED: transaction is paused
  * @DMA_ERROR: transaction failed
  */
 enum dma_status {
-	DMA_SUCCESS,
+	DMA_COMPLETE,
 	DMA_IN_PROGRESS,
 	DMA_PAUSED,
 	DMA_ERROR,
+	DMA_SUCCESS,
 };
 
 /**

and then in a couple of places

-			return DMA_SUCCESS;
+			return DMA_COMPLETE;

So, after that your patch dmaengine would be returning DMA_COMPLETE in 
case of success, i.e. 0. But all the DMAC and user drivers would still be 
checking for

	if (status != DMA_COMPLETE) {

i.e. comparing status with 4 and thus detecting false errors, until your 
further 28 patches fix them. That's why, as Sebastian pointed out it was 
important to define DMA_COMPLETE and DMA_SUCCESS with the _same_ numerical 
value in your patch 1.

> Both were pushed to -next after few days

That's a pity, but I still don't see them in upstream -next, so, maybe 
it's still possible to fix?

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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