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

[Kuninori Morimoto]

Hi Takashi

> > I tested this patch-set.
> > I noticed that it doesn't work if I used DPCM
> > (Kernel has Oops).
> > I will investigate it next week
> 
> Could you show the Oops message if you have?
> My concern is whether it happens by stopping at disconnect, or it's
> just another missing piece.

OK, but kernel log doesn't help you.
see below

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.

-----------------------
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 2fec2fe..972408b 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1241,7 +1241,8 @@ static int snd_pcm_do_stop(struct snd_pcm_substream *substream, int state)
 {
 	if (substream->runtime->trigger_master == substream &&
 	    snd_pcm_running(substream))
-		substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_STOP);
+		if (substream->ops && substream->ops->trigger)
+			substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_STOP);
 	return 0; /* unconditonally stop all substreams */
 }
-----------------------
 
After this patch, my driver side clock counter mismatch Oops happen.
It seems this is because FE side wasn't called snd_pcm_stop();
(= BE side only called snd_pcm_stop()).

I could confirm this by printing who's stop was called by local quick hack.

Maybe timing reason, if kernel has Oops for some reasons,
then, both BE/FE snd_pcm_stop() are called.
If no Oops, BE snd_pcm_stop() only called.

Best regards
---
Kuninori Morimoto