linux-kernel - Re: [PATCH 1/4] dt-bindings: Document the STM32 DMA bindings

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Message-ID: <11583587.xphxbMQ7TN@wuerfel>
Date:	Thu, 08 Oct 2015 22:40:19 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	M'boumba Cedric Madianga <cedric.madianga@...il.com>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, Kumar Gala <galak@...eaurora.org>,
	linux@....linux.org.uk, vinod.koul@...el.com,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	dmaengine@...r.kernel.org
Subject: Re: [PATCH 1/4] dt-bindings: Document the STM32 DMA bindings

On Thursday 08 October 2015 22:25:50 M'boumba Cedric Madianga wrote:
> >
> > How do you know which channels are available for memory-to-memory
> > transfers?
> For memory-to-memory transfer we don't need any channel/request combination.
> We look for any available channel in the channel list to execute our transfer.
> So, as often as possible, we expect that a peripheral release his
> channel after transfering data.
> In that way, we always should have at least one channel available for
> that kind of transfer.
> 

Ah, got it. So the use of virtual channels in this driver makes MEM2MEM
transfers work, but is otherwise not required.

Thanks for the clarification.

	Arnd
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