On 10/8/19 1:53 AM, Kuninori Morimoto wrote:

Hi ALSA ML.

I'm checking soc-pcm.c, and I noticed strange code at dpcm_prune_paths().

static int dpcm_prune_paths(...) { ... /* Destroy any old FE <--> BE connections */ (1) for_each_dpcm_be(fe, stream, dpcm) { unsigned int i;

• 	/* is there a valid CPU DAI widget for this BE */
  

| widget = dai_get_widget(dpcm->be->cpu_dai, stream); | (A) /* prune the BE if it's no longer in our active list */ | if (widget && widget_in_list(list, widget)) |(a) continue;

| /* is there a valid CODEC DAI widget for this BE */ |(2) for_each_rtd_codec_dai(dpcm->be, i, dai) { | widget = dai_get_widget(dai, stream); (B) | /* prune the BE if it's no longer in our active list */ | if (widget && widget_in_list(list, widget)) |(b) continue;

• 	}
  
  

• 	...
  

| dpcm->state = ... (C) dpcm->be->dpcm[stream].runtime_update = ... | prune++;

• }
  

  ...

}

In my understanding, (A) part is for CPU, and (B) part is for Codec. Guessing from (a), I think it want to skip setup (C) if CPU widget exist and matches to list. If so, I guess (b) is maybe bug ? This continue is for (2) loop, thus, it is totally do nothing now. But maybe it want to be continue for (1) loop ?

Nice catch. This looks like a problem added during the transition to multi-codec.

The code before 2e5894d73789 ('ASoC: pcm: Add support for DAI multicodec') was this:

/* is there a valid CODEC DAI widget for this BE */ widget = dai_get_widget(dpcm->be->codec_dai, stream);

/* prune the BE if it's no longer in our active list */ if (widget && widget_in_list(list, widget)) continue;

and the addition of the loop for the codec seems incorrect

/* is there a valid CODEC DAI widget for this BE */ for (i = 0; i < dpcm->be->num_codecs; i++) { struct snd_soc_dai *dai = dpcm->be->codec_dais[i]; widget = dai_get_widget(dai, stream);

/* prune the BE if it's no longer in our active list */ if (widget && widget_in_list(list, widget)) continue; }

the continue was not meant to continue the for loop on num_codecs, but the outer loop for dpcm.