[alsa-devel] [PATCH v2 0/2] Add snd_card_disconnect_sync() helper

[Mark Brown]

On Fri, Oct 13, 2017 at 11:43:59AM +0200, Takashi Iwai wrote:
> Kuninori Morimoto wrote:

> > My environment now is I'm using DPCM.
> > 	FE : rsnd
> > 	FE : rsnd
> > 	BE : ak4613

> > 1st issue is that kernel need below patch.
> > I guess BE is using dummy driver, and it doesn't have ops(?).
> > If this is needed, I can post it.

> No, this can't be right.  Every PCM implementation mandates the
> presence of a trigger callback.  It's a must.  If a fix needed, it has
> to be fixed in the driver side.

I suspect this is a DPCM framework thing - when the paths are joined up
at runtime there's going to be at least one trigger in there but with
DPCM it's most likely going to be in the front end, the back end DMA is
often going to be transparent to the system and so not have a trigger.
However if you just iterate over all the PCMs you'll see the decomposed
front and back end links with their dummies in there.  Not sure what the
fix is here, probably we need to be hiding the back end links more from
the ALSA core.

Liam?
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: not available
URL: <http://mailman.alsa-project.org/pipermail/alsa-devel/attachments/20171013/a5479dc3/attachment.sig>