I have been wondering why DPCM needs special flag (= dpcm_playback/capture) to use it. Below is the history why it was added to ASoC.
(A) In beginning, there was no dpcm_xxx flag on ASoC. It checks channels_min for DPCM, same as current non-DPCM. Let's name it as "validation check" here.
if (rtd->dai_link->dynamic || rtd->dai_link->no_pcm) { if (cpu_dai->driver->playback.channels_min) playback = 1; if (cpu_dai->driver->capture.channels_min) capture = 1;
(B) commit 1e9de42f4324 ("ASoC: dpcm: Explicitly set BE DAI link supported stream directions") force to use dpcm_xxx flag on DPCM. According to this commit log, this is because "Some BE dummy DAI doesn't set channels_min for playback/capture". But we don't know which DAI is it, and not know why it can't/don't have channels_min. Let's name it as "no_chan_DAI" here. According to the code and git-log, it is used as DCPM-BE and is CPU DAI. I think the correct solution was set channels_min on "no_chan_DAI" side, not update ASoC framework side. But everything is under smoke today.
if (rtd->dai_link->dynamic || rtd->dai_link->no_pcm) { playback = rtd->dai_link->dpcm_playback; capture = rtd->dai_link->dpcm_capture;
(C) commit 9b5db059366a ("ASoC: soc-pcm: dpcm: Only allow playback/capture if supported") checks channels_min (= validation check) again. Because DPCM availability was handled by dpcm_xxx flag at that time, but some Sound Card set it even though it wasn't available. Clearly there's a contradiction here. I think correct solution was update Sound Card side instead of ASoC framework. Sound Card side will be updated to handle this issue later (commit 25612477d20b ("ASoC: soc-dai: set dai_link dpcm_ flags with a helper"))
if (rtd->dai_link->dynamic || rtd->dai_link->no_pcm) { ... playback = rtd->dai_link->dpcm_playback && snd_soc_dai_stream_valid(cpu_dai, ...); capture = rtd->dai_link->dpcm_capture && snd_soc_dai_stream_valid(cpu_dai, ...);
This (C) patch should have broken "no_chan_DAI" which doesn't have channels_min, but there was no such report during this 4 years. Possibilities case are as follows - No one is using "no_chan_DAI" - "no_chan_DAI" is no longer exist : was removed ? - "no_chan_DAI" is no longer exist : has channels_min ?
Because of these history, this dpcm_xxx is unneeded flag today. But because we have been used it for 10 years since (B), it may have been used differently. For example some DAI available both playback/capture, but it set dpcm_playback flag only, in this case dpcm_xxx flag is used as availability limitation. We can use playback_only flag instead in this case, but it is very difficult to find such DAI today.
Let's add grace time to remove dpcm_playback/capture flag.
This patch don't use dpcm_xxx flag anymore, and indicates warning to use xxx_only flag if both playback/capture were available but using only one of dpcm_xxx flag, and not using xxx_only flag.
Link: https://lore.kernel.org/r/87edaym2cg.wl-kuninori.morimoto.gx@renesas.com Signed-off-by: Kuninori Morimoto kuninori.morimoto.gx@renesas.com Tested-by: Jerome Brunet jbrunet@baylibre.com --- include/sound/soc.h | 1 + sound/soc/soc-pcm.c | 65 ++++++++++++++++++++++++++------------------- 2 files changed, 38 insertions(+), 28 deletions(-)
diff --git a/include/sound/soc.h b/include/sound/soc.h index 33671437ee89..2a3da1d91377 100644 --- a/include/sound/soc.h +++ b/include/sound/soc.h @@ -815,6 +815,7 @@ struct snd_soc_dai_link { /* This DAI link can route to other DAI links at runtime (Frontend)*/ unsigned int dynamic:1;
+ /* REMOVE ME */ /* DPCM capture and Playback support */ unsigned int dpcm_capture:1; unsigned int dpcm_playback:1; diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c index 711b2f49ed88..7fe5ee3bcfd4 100644 --- a/sound/soc/soc-pcm.c +++ b/sound/soc/soc-pcm.c @@ -2795,6 +2795,7 @@ static int soc_get_playback_capture(struct snd_soc_pcm_runtime *rtd, { struct snd_soc_dai_link *dai_link = rtd->dai_link; struct snd_soc_dai *cpu_dai; + struct snd_soc_dai_link_ch_map *ch_maps; int has_playback = 0; int has_capture = 0; int i; @@ -2805,43 +2806,51 @@ static int soc_get_playback_capture(struct snd_soc_pcm_runtime *rtd, }
if (dai_link->dynamic || dai_link->no_pcm) { - int stream;
- if (dai_link->dpcm_playback) { - stream = SNDRV_PCM_STREAM_PLAYBACK; + for_each_rtd_ch_maps(rtd, i, ch_maps) { + cpu_dai = snd_soc_rtd_to_cpu(rtd, ch_maps->cpu);
- for_each_rtd_cpu_dais(rtd, i, cpu_dai) { - if (snd_soc_dai_stream_valid(cpu_dai, stream)) { - has_playback = 1; - break; - } - } - if (!has_playback) { - dev_err(rtd->card->dev, - "No CPU DAIs support playback for stream %s\n", - dai_link->stream_name); - return -EINVAL; - } + if (snd_soc_dai_stream_valid(cpu_dai, SNDRV_PCM_STREAM_PLAYBACK)) + has_playback = 1; + + if (snd_soc_dai_stream_valid(cpu_dai, SNDRV_PCM_STREAM_CAPTURE)) + has_capture = 1; } - if (dai_link->dpcm_capture) { - stream = SNDRV_PCM_STREAM_CAPTURE;
- for_each_rtd_cpu_dais(rtd, i, cpu_dai) { - if (snd_soc_dai_stream_valid(cpu_dai, stream)) { - has_capture = 1; - break; - } + /* + * REMOVE ME + * + * dpcm_xxx flag will be removed soon, Indicates warning if dpcm_xxx flag was used + * as availability limitation + */ + if (has_playback && has_capture) { + if ( dai_link->dpcm_playback && + !dai_link->dpcm_capture && + !dai_link->playback_only) { + dev_warn(rtd->card->dev, + "both playback/capture are available," + " but not using playback_only flag (%s)\n", + dai_link->stream_name); + dev_warn(rtd->card->dev, + "dpcm_playback/capture are no longer needed," + " please use playback/capture_only instead\n"); + has_capture = 0; }
- if (!has_capture) { - dev_err(rtd->card->dev, - "No CPU DAIs support capture for stream %s\n", - dai_link->stream_name); - return -EINVAL; + if (!dai_link->dpcm_playback && + dai_link->dpcm_capture && + !dai_link->capture_only) { + dev_warn(rtd->card->dev, + "both playback/capture are available," + " but not using capture_only flag (%s)\n", + dai_link->stream_name); + dev_warn(rtd->card->dev, + "dpcm_playback/capture are no longer needed," + " please use playback/capture_only instead\n"); + has_playback = 0; } } } else { - struct snd_soc_dai_link_ch_map *ch_maps; struct snd_soc_dai *codec_dai;
/* Adapt stream for codec2codec links */