From mboxrd@z Thu Jan  1 00:00:00 1970
From: Lars-Peter Clausen <lars@metafoo.de>
Subject: Re: DMA engine API issue
Date: Thu, 24 Jul 2014 14:29:09 +0200
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To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Kuninori Morimoto <kuninori.morimoto.gx@gmail.com>
Cc: Linux-ALSA <alsa-devel@alsa-project.org>, linux-sh@vger.kernel.org, Vinod Koul <vinod.koul@intel.com>, Magnus Damm <magnus.damm@gmail.com>, dmaengine@vger.kernel.org, Maxime Ripard <maxime.ripard@free-electrons.com>, linux-arm-kernel@lists.infradead.org
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On 07/23/2014 01:07 PM, Laurent Pinchart wrote:
[...]
> Let's start by answering the background question and updating the DMA engine
> API documentation once and for good : in which context are drivers allowed to
> call the prep, tx_submit and issue_pending functions ?
>

I think the expectation is that these functions can be called in any 
context. Maybe what's missing is a way to tell the DMA engine driver to get 
ready and that it is going to be used very soon. This could be done from the 
sound devices open() callback.

- Lars