On Tue, Jun 16, 2020 at 12:05:49PM -0500, Pierre-Louis Bossart wrote: > > > > > > > simple-card.c and audio-graph-card do hard-code but that's done > > > > with C in > > > > the driver: > > > > > > > > ret = asoc_simple_parse_daifmt(dev, cpu_ep, codec_ep, > > > > NULL, &dai_link->dai_fmt); > > > > if (ret < 0) > > > > goto out_put_node; > > > > > > > > dai_link->dpcm_playback = 1; > > > > dai_link->dpcm_capture = 1; > > > > > > > > > > > > that that should be fixed based on the DAI format used in that > > > > dai_link - in > > > > other words we can make sure the capabilities of the dailink are aligned > > > > with the dais while parsing the DT blobs. > > > > > > But how do you know which capabilities to set? The device tree doesn't > > > tells us that. We could add some code to look up the snd_soc_dai_driver > > > early, based on the references in the device tree (basically something > > > like snd_soc_of_get_dai_name(), see > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/sound/soc/soc-core.c#n2988) > > > > > > > > > At least to me that function doesn't exactly look trivial though, > > > and that's just to properly fill in the dpcm_playback/capture > > > parameters. Essentially those parameters only complicate the current > > > device tree use case, where you want the DAI link to be for both > > > playback/capture, but restricted to the capabilities of the DAI. > > > > > > Just wondering if setting up dpcm_playback/capture properly is worth it > > > at all in this case. This isn't necessary for the non-DPCM case either, > > > there we automatically set it based on the DAI capabilities. > > > > We can add a simple loop for each direction that relies on > > snd_soc_dai_stream_valid() to identify if each DAI is capable of doing > > playback/capture. > > see below completely untested diff to show what I had in mind: we already > make use of snd_soc_dai_stream_valid() in other parts of the core so we > should be able to determine dpcm_playback/capture based on the same > information already used. > > diff --git a/sound/soc/generic/audio-graph-card.c > b/sound/soc/generic/audio-graph-card.c > index 9ad35d9940fe..4c67f1f65eb4 100644 > --- a/sound/soc/generic/audio-graph-card.c > +++ b/sound/soc/generic/audio-graph-card.c > @@ -215,7 +215,9 @@ static int graph_dai_link_of_dpcm(struct > asoc_simple_priv *priv, > struct asoc_simple_dai *dai; > struct snd_soc_dai_link_component *cpus = dai_link->cpus; > struct snd_soc_dai_link_component *codecs = dai_link->codecs; > + int stream; > int ret; > + int i; > > /* Do it all CPU endpoint, and 1st Codec endpoint */ > if (!li->cpu && dup_codec) > @@ -317,8 +319,34 @@ static int graph_dai_link_of_dpcm(struct > asoc_simple_priv *priv, > if (ret < 0) > goto out_put_node; > > - dai_link->dpcm_playback = 1; > - dai_link->dpcm_capture = 1; > + for_each_pcm_streams(stream) { > + struct snd_soc_dai_link_component *cpu; > + struct snd_soc_dai_link_component *codec; > + struct snd_soc_dai *d; > + bool dpcm_direction = true; > + > + for_each_link_cpus(dai_link, i, cpu) { > + d = snd_soc_find_dai(cpu); > + if (!d || !snd_soc_dai_stream_valid(d, stream)) { > + dpcm_direction = false; > + break; > + } > + } > + for_each_link_codecs(dai_link, i, codec) { > + d = snd_soc_find_dai(codec); > + if (!d || !snd_soc_dai_stream_valid(d, stream)) { > + dpcm_direction = false; > + break; > + } > + } > + if (dpcm_direction) { > + if (stream == SNDRV_PCM_STREAM_PLAYBACK) > + dai_link->dpcm_playback = 1; > + if (stream == SNDRV_PCM_STREAM_CAPTURE) > + dai_link->dpcm_capture = 1; > + } > + } > + > dai_link->ops = &graph_ops; > dai_link->init = asoc_simple_dai_init; > Thanks for the diff! I tested it for my case and it seems to work fine so far. I'm fine with this solution given that it fixes the problem I mentioned. We would need to patch it into at least simple-audio-card.c, audio-graph-card.c and soc/qcom/common.c (probably best to create a shared function in soc-core.c then). However, personally I still think that dpcm_playback/capture essentially just duplicate the capabilities that are already exposed as part of the DAI drivers. We don't need that duplication in the non-DPCM case, so I wonder if we really need it for DPCM. With your diff we go over all the DAIs to set dpcm_playback/capture correctly so that soc_new_pcm() can then verify that they were set correctly. IMO it would be much simpler to restore the previous behavior and just make soc_new_pcm() rely on the DAI capabilities to decide if playback/capture is supported, without producing the error. Thanks, Stephan
