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;
