meson-aiu: HDMI codec .prepare() callback not called

Commit Message

Martin Blumenstingl Dec. 31, 2024, 6:44 p.m. UTC

Hi Jerome,

I am still working on a HDMI controller driver for Meson8/8b/8m2.
HDMI output would be incomplete without audio.
There's a great series from Dmitry [0] which simplifies the HDMI
controller driver implementation by moving all the hdmi-codec related
management to a generic framework.

I tried integrating Dmitry's work [0] into my HDMI controller driver.
While testing I found that hdmi-codec's .prepare() callback is not
called at all and asked Dmitry for help [1]. All other callbacks
(.hw_params, .startup, .shutdown, ...) however are called.
On his board (Qualcomm SDM845, sdm845-db845c.dts) hdmi_codec_prepare()
is called by snd_soc_pcm_dai_prepare() (core sound framework, not
platform specific).
However, on my Odroid-C1 this is not happening.

Looking further snd_soc_pcm_dai_prepare() I can see that
for_each_rtd_dais() has three entries:
  snd_soc_pcm_dai_prepare(), dai name=I2S Encoder, id=2
  snd_soc_pcm_dai_prepare(), dai name=CODEC CTRL HDMI I2S IN, id=0
  snd_soc_pcm_dai_prepare(), dai name=I2S FIFO, id=0
What I'm missing here is a dai name "i2s-hifi" (from
sound/soc/codecs/hdmi-codec.c, see hdmi_i2s_dai)

My hdmi_tx node looks like this (abbreviated):
  hdmi_tx: hdmi-tx@42000 {
      compatible = "amlogic,meson8b-hdmi-tx";
      reg = <0x42000 0xc>;
      #sound-dai-cells = <1>;
       ...
  };

Then I have a "amlogic,gx-sound-card" instance with the following dai-links:
  dai-link-0 {
      sound-dai = <&aiu AIU_CPU CPU_I2S_FIFO>;
  };
  dai-link-1 {
      sound-dai = <&aiu AIU_CPU CPU_I2S_ENCODER>;
      dai-format = "i2s";
      mclk-fs = <256>;

      codec-0 {
          sound-dai = <&aiu AIU_HDMI CTRL_I2S>;
    };
  };
  dai-link-2 {
      sound-dai = <&aiu AIU_HDMI CTRL_OUT>;

      codec-0 {
          sound-dai = <&hdmi_tx 0>;
      };
  };
So apart from the additional cell in the sound-dai towards hdmi_tx
(Meson8/8b/8m2's HDMI controller has two inputs: I2C and SPDIF. I2C is
the first one, hence &hdmi_tx 0) this is identical to
arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts.

I have further verified that the gx-card parsing does find the HDMi
controller and links it correctly.
To me it's odd that only the .prepare() callback is not called, all
others (as mentioned above: .hw_params, .startup, ...) are working
fine.

I'm not familiar with the sound stack and I'm hoping that you have
some ideas on how to either debug or fix it.


Thanks in advance and best regards,
Martin


[0] https://lore.kernel.org/dri-devel/[e-mail]/
[1] https://lore.kernel.org/dri-devel/[e-mail]/
[2] https://lore.kernel.org/dri-devel/l3u3wtnxyhrwjynevkwfjwarisc4yt4xy2rbzf5kb7k5l5dw3n@lxqtimymyjg6/

Patch

diff --git a/drivers/gpu/drm/display/drm_hdmi_audio_helper.c b/drivers/gpu/drm/display/drm_hdmi_audio_helper.c
index aa3a5d0329dc..05afc9f0bdd6 100644
--- a/drivers/gpu/drm/display/drm_hdmi_audio_helper.c
+++ b/drivers/gpu/drm/display/drm_hdmi_audio_helper.c
@@ -129,7 +129,6 @@  EXPORT_SYMBOL(drm_connector_hdmi_audio_plugged_notify);
 static const struct hdmi_codec_ops drm_connector_hdmi_audio_ops = {
 	.audio_startup = drm_connector_hdmi_audio_startup,
 	.prepare = drm_connector_hdmi_audio_prepare,
-	.hw_params = drm_connector_hdmi_audio_prepare,
 	.audio_shutdown = drm_connector_hdmi_audio_shutdown,
 	.mute_stream = drm_connector_hdmi_audio_mute_stream,
 	.get_eld = drm_connector_hdmi_audio_get_eld,
diff --git a/sound/soc/codecs/hdmi-codec.c b/sound/soc/codecs/hdmi-codec.c
index 69f98975e14a..a931d05ba89e 100644
--- a/sound/soc/codecs/hdmi-codec.c
+++ b/sound/soc/codecs/hdmi-codec.c
@@ -570,13 +570,13 @@  static int hdmi_codec_hw_params(struct snd_pcm_substream *substream,
 	};
 	int ret;
 
-	if (!hcp->hcd.ops->hw_params)
-		return 0;
-
-	dev_dbg(dai->dev, "%s() width %d rate %d channels %d\n", __func__,
+	dev_info(dai->dev, "%s() width %d rate %d channels %d\n", __func__,
 		params_width(params), params_rate(params),
 		params_channels(params));
 
+	if (!hcp->hcd.ops->hw_params)
+		return 0;
+
 	ret = hdmi_codec_fill_codec_params(dai,
 					   params_width(params),
 					   params_rate(params),
@@ -611,12 +611,12 @@  static int hdmi_codec_prepare(struct snd_pcm_substream *substream,
 	struct hdmi_codec_params hp;
 	int ret;
 
+	dev_info(dai->dev, "%s() width %d rate %d channels %d\n", __func__,
+		width, rate, channels);
+
 	if (!hcp->hcd.ops->prepare)
 		return 0;
 
-	dev_dbg(dai->dev, "%s() width %d rate %d channels %d\n", __func__,
-		width, rate, channels);
-
 	ret = hdmi_codec_fill_codec_params(dai, width, rate, channels, &hp);
 	if (ret < 0)
 		return ret;
diff --git a/sound/soc/soc-dai.c b/sound/soc/soc-dai.c
index 34ba1a93a4c9..030c573753cc 100644
--- a/sound/soc/soc-dai.c
+++ b/sound/soc/soc-dai.c
@@ -577,6 +577,7 @@  int snd_soc_pcm_dai_prepare(struct snd_pcm_substream *substream)
 	int i, ret;
 
 	for_each_rtd_dais(rtd, i, dai) {
+		pr_info("%s(), dai name=%s, id=%d\n", __func__, dai->name, dai->id);
 		if (!snd_soc_dai_stream_valid(dai, substream->stream))
 			continue;
 		if (dai->driver->ops &&