Re: [PATCH 2/3] ASoC: add function parameters to enable forced path pruning

[Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>]

Hi Mark,

On Tue, Mar 10, 2020 at 12:45:44PM +0000, Mark Brown wrote:
> On Mon, Mar 09, 2020 at 06:07:48PM +0100, Guennadi Liakhovetski wrote:
> 
> > soc_dpcm_runtime_update() to activate an audio path and update audio
> > routing. When streaming is stopped, the vhost driver calls
> > soc_dpcm_runtime_update() and snd_soc_runtime_deactivate(). The latter
> > doesn't work at the moment, because the DPCM doesn't recognise the
> > path as inactive. We address this by adding a "mode" parameter to
> > soc_dpcm_runtime_update(). If virtualisation isn't used, the current
> > behaviour isn't affected.
> 
> So why doesn't DPCM recognize that the path is inactive and why is it
> better to do this than fix whatever the issue is there?

Of course that would be better abd I'd much prefer that. Unfortunately I 
haven't been able to find a single scenario in which those paths would be 
exercised. As far as I understand path pruning should take place e.g. 
when a mixer modifies audio routing and as a result disables a certain 
pipeline, which is then pruned. If I could reproduce such a scenario I 
would be able to first check whether it's working, then see exactly how 
it is working and then see how best to add my use case to it. Since I 
wasn't able to find such a scenario, my only option was to preserve 
the current state and add my own path "on top." I'd be happy to try the 
other path too, I just need a use case, that I can reproduce.

Thanks
Guennadi