linux-kernel - Re: [alsa-devel] [PATCH v5] sound/soc/lapis: add platform driver for ML7213

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Message-ID: <20120531104538.GA2666@opensource.wolfsonmicro.com>
Date:	Thu, 31 May 2012 11:45:38 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Tomoya MORINAGA <tomoya.rohm@...il.com>
Cc:	Vinod Koul <vinod.koul@...ux.intel.com>,
	alsa-devel@...a-project.org, lars@...afoo.de,
	Takashi Iwai <tiwai@...e.de>, linux-kernel@...r.kernel.org,
	Liam Girdwood <lrg@...com>
Subject: Re: [alsa-devel] [PATCH v5] sound/soc/lapis: add platform driver for
 ML7213

On Thu, May 31, 2012 at 02:38:30PM +0900, Tomoya MORINAGA wrote:
> On Wed, May 30, 2012 at 9:14 PM, Mark Brown

> > Please re-read what I wrote.

> Let me clarify.
> Do you say native DMA driver API like dmaengine_prep_slave_sg(),
> dmaengine_submit() shouldn't be used from ASoC driver, right ?

Your driver should be written in terms of the ASoC DMA framework.

> > No, all current mainline drivers using the library use cyclic DMA.

> I can't see any driver uses cyclic DMA. (I saw linux-next's tree from
> kernel.org.)
> Where is your saying "current mainline" ?

Linus' tree, or mine.  Have you even looked at the soc-dmaengine-pcm
code?  It uncondtionally requests a cyclic channel.

> However I think it seems difficult for supporting all devices.
> Because hardware dependency control code can't be added.
> For example, for ML7213, needs interrupt control both before/after DMA transfer.
> However,  in case of using soc-dmaengine, the control can't be done.
> Because the processing is in soc-dmaengine.

Please be more specific.  What are the concrete problems that you see?
Why is it not possible to address them within the framework?

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