linux-kernel - Re: [PATCH] dma: mdc: Correct terminate

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Message-ID: <20151210042029.GQ1854@localhost>
Date:	Thu, 10 Dec 2015 09:50:29 +0530
From:	Vinod Koul <vinod.koul@...el.com>
To:	Damien Horsley <Damien.Horsley@...tec.com>
Cc:	dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
	Dan Williams <dan.j.williams@...el.com>,
	James Hartley <James.Hartley@...tec.com>
Subject: Re: [PATCH] dma: mdc: Correct terminate_all handling

On Mon, Dec 07, 2015 at 04:59:41PM +0000, Damien Horsley wrote:
> On 05/12/15 08:43, Vinod Koul wrote:
> > On Mon, Nov 23, 2015 at 02:22:04PM +0000, Damien Horsley wrote:
> >> From: "Damien.Horsley" <Damien.Horsley@...tec.com>
> >>
> >> Use of the CANCEL bit in mdc_terminate_all creates an
> >> additional 'command done' to appear in the registers (in
> >> addition to an interrupt).
> >>
> >> In addition, there is a potential race between
> >> mdc_terminate_all and the irq handler if a transfer
> >> completes at the same time as the terminate all (presently
> >> this results in an inappropriate warning).
> >>
> >> To handle these issues, any outstanding 'command done'
> >> events are cleared during mdc_terminate_all and the irq
> >> handler takes no action when there are no new 'command done'
> >> events.
> > 
> > SO what does 'command done' event represent, and what would be the behaviour
> > of ignoring those
> > 
> 
> The 'command done' event occurs whenever a new descriptor is loaded from
> memory, and once when the whole transfer is completed. Use of the CANCEL
> bit can cause additional 'command done' events to occur, which need to
> be cleared.

Okay, btw please fix the subsystem name. I'ts dmaengine

-- 
~Vinod
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