[alsa-devel] [PATCH 0/2] ASoC: dmaengine_pcm: support generic DMA binding users

Russell King - ARM Linux linux at arm.linux.org.uk
Fri Mar 22 12:30:56 CET 2013

On Thu, Mar 21, 2013 at 05:26:19PM +0100, Lars-Peter Clausen wrote:
> The problem with the current library is that we don't know yet which
> dmaengine device is going to be used by the time we pre-allocate the
> audio buffers, since the DMA filter parameters often are provided by
> the DAI driver.

That's not really a problem.  The CPU DAI can provide the data via
the playback_dma_data and capture_dma_data pointers, which the ASoC
DMA engine driver can pick up on when it initializes.  This data can
contain everything that the ASoC DMA engine driver needs.

Where my driver falls down is if you need to reconfigure the DMA engine
later - it doesn't provide an API for that, but that's trivially easy
to augment the API.

If you want to look at what I did for sa11x0 Assabet platforms, it's
still all here:


As you will see from the dates, it's over a year old now - the only
thing I do with it is occasionally rebase it to bring it up to a more
modern kernel.

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