[alsa-devel] [PATCH 07/11] ASoC: tegra: Add tegra-das driver

Mark Brown broonie at opensource.wolfsonmicro.com
Thu Jan 6 00:33:38 CET 2011

On Wed, Jan 05, 2011 at 03:27:17PM -0800, Stephen Warren wrote:
> Mark Brown wrote:

> > No, I don't think this should be made visible to machine drivers at all
> > - they should just see a straight through mapping from the DMA channels
> > to the ports in the first instance.

> Oh. So what should set up this 1:1 mapping then; what module should the
> DAS register writes be contained in? And later, what module should

I guess the I2S driver?

> configure the DAS with the mux configuration that is appropriate for
> the board? It seems like the machine driver is the only place with the

My suggestion would only work for very simple boards like Harmony.

> knowledge to define what the routing should be. Whether the machine driver
> calls tegra_das_* vs. some codec/mux API to set this up seems like a
> different issue to whether the machine driver or something else should
> contain this knowledge.

The end result would be that this would all be done in the application
layer, potentially dynamically.

> In the short-term, are you expecting the I2S driver to expose a CPU DAI for
> each audio controller and port? The number of audio controllers and ports
> isn't equal, and hence it wouldn't be possible to support a board using just
> port 5 since there's no controller 5 (and even audio controller 3 I think is
> SPDIF not I2S)...

Oh, hrm.  That wasn't clear from your code.  Would mapping controller n
to port n work for Harmony?

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