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

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Message-ID: <Pine.LNX.4.64.1310250840350.6186@axis700.grange>
Date:	Fri, 25 Oct 2013 08:43:13 +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

On Fri, 25 Oct 2013, Vinod Koul wrote:

> On Fri, Oct 25, 2013 at 08:32:12AM +0200, Guennadi Liakhovetski wrote:
> > 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.
> Sure, I will fix this up now as suggested
> 
>   enum dma_status {
>  -	DMA_SUCCESS,
>  +	DMA_COMPLETE = 0, DMA_SUCCESS = 0,
> 
> Thanks for poiting out.

Great! In my reply to Sebastian I proposed an equivlent but slightly 
different version:

 enum dma_status {
-	DMA_SUCCESS,
+	DMA_COMPLETE,
 	DMA_IN_PROGRESS,
 	DMA_PAUSED,
 	DMA_ERROR,
 };
 
+ #define DMA_SUCCESS DMA_COMPLETE

but it doesn't really matter. Feel free to use whichever version you 
prefer.

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