[alsa-devel] [PATCH 1/5] ASoC: Hold runtime PM references to components of active DAIs

Peter Ujfalusi peter.ujfalusi at ti.com
Mon Dec 5 15:53:00 CET 2011

On 12/05/2011 03:46 PM, Mark Brown wrote:
> Well, the pcm_mutex doesn't cover all of those anyway (trigger and
> pointer in particular) and we've no guarantee that anything will
> actually happen at the point where the core does the calls as there may
> be other things holding the device active.

It covers the soc_pcm_open, and soc_pcm_close sequences.

> I don't understand how this could make the situation any worse than it
> is already - if nothing else this series will only make the region where
> we've got the device active slightly wider.

The ordering of the pm_runtime_get/put will be different.
We will have the pm_runtime_put after all other parts of the audio
system has been closed, turned off.

> There's definitely an issue
> there, but it seems like it already exists and is orthogonal to this
> refactoring.  The McPDM needs to hold a reference on the CODEC somehow
> while it is active it seems, either via DAPM or via the runtime_pm APIs.

Yes, this is the reason we do not have the BIAS_OFF support in twl6040
still. I'm working on to integrate the external fclk (bit clock from
twl6040) for McPDM with pm_runtime so we are not going to have issues
with missing clocks.
But as I said at this time we do not have issues since the fclk for
McPDM is always present.
This change actually gives more incentive to do the pm_runtime support
for the McPDM external fclk ;)


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