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Message-ID: <5052F8BC.4020102@ti.com>
Date: Fri, 14 Sep 2012 12:28:28 +0300
From: Peter Ujfalusi <peter.ujfalusi@ti.com>
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To: Vinod Koul <vinod.koul@linux.intel.com>
CC: Lars-Peter Clausen <lars@metafoo.de>,
        Mark Brown <broonie@opensource.wolfsonmicro.com>,
        Liam Girdwood <lrg@ti.com>, Tony Lindgren <tony@atomide.com>,
        Russell King <rmk+kernel@arm.linux.org.uk>, Dan Williams <djbw@fb.com>,
        Jarkko Nikula <jarkko.nikula@bitmer.com>, alsa-devel@alsa-project.org,
        linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org,
        Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>,
        Ricardo Neri <ricardo.neri@ti.com>
Subject: Re: [PATCH v2 03/15] dmaengine: Add no_wakeup parameter to dmaengine_prep_dma_cyclic()
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Hi,

On 09/14/2012 11:50 AM, Vinod Koul wrote:
>> Well, the idea was that the driver would disable interrupts if there is no
>> callback to call, since there would be nothing to do in the interrupt
>> handler anyway. But I guess the flags approach should work fine as well.
> Yes we _could_ do that, but this relies on dmaengine driver to have this
> implicit understanding. Anyone using dmaengine library in ASoC may or
> may not be aware of this, so i would consider it hackish.
> 
> Using this flag explicitly makes everyone aware what the intended
> behaviour is.

I'm not sure about which flags should ASoC set for the two case we are going
to have. I think it should be something like this:

unsigned long flags = DMA_CTRL_ACK;

if (!substream->runtime->no_period_wakeup)
	flags |= DMA_PREP_INTERRUPT;

I'm not 100% sure of the role of DMA_CTRL_ACK in this case. Or should we only
handle the DMA_PREP_INTERRUPT flag, like this:

unsigned long flags = 0;

if (!substream->runtime->no_period_wakeup)
	flags |= DMA_PREP_INTERRUPT;


What do you think?

-- 
Péter