[alsa-devel] [PATCH 4/4] ASoC: tda998x: adjust the audio hw parameters from EDID

[Jean-Francois Moine]

The supported audio parameters are described in the EDID which is
received by the HDMI transmitter from the connected screen.
Use these ones to adjust the audio stream parameters.

Signed-off-by: Jean-Francois Moine <moinejf at free.fr>
---
 drivers/gpu/drm/i2c/tda998x_drv.c | 15 ++++++++
 include/drm/i2c/tda998x.h         |  1 +
 sound/soc/codecs/tda998x.c        | 79 ++++++++++++++++++++++++++++++++++++++-
 3 files changed, 94 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
index 186c751..3c8b4d7 100644
--- a/drivers/gpu/drm/i2c/tda998x_drv.c
+++ b/drivers/gpu/drm/i2c/tda998x_drv.c
@@ -45,6 +45,8 @@ struct tda998x_priv {
 	wait_queue_head_t wq_edid;
 	volatile int wq_edid_wait;
 	struct drm_encoder *encoder;
+
+	u8 *eld;
 };
 
 #define to_tda998x_priv(x)  ((struct tda998x_priv *)to_encoder_slave(x)->slave_priv)
@@ -731,6 +733,14 @@ tda998x_configure_audio(struct tda998x_priv *priv,
 }
 
 /* tda998x codec interface */
+u8 *tda998x_audio_get_eld(struct i2c_client *client)
+{
+	struct tda998x_priv *priv = i2c_get_clientdata(client);
+
+	return priv->eld;
+}
+EXPORT_SYMBOL_GPL(tda998x_audio_get_eld);
+
 void tda998x_audio_update(struct i2c_client *client,
 			int format,
 			int port)
@@ -1186,6 +1196,11 @@ tda998x_encoder_get_modes(struct drm_encoder *encoder,
 		drm_mode_connector_update_edid_property(connector, edid);
 		n = drm_add_edid_modes(connector, edid);
 		priv->is_hdmi_sink = drm_detect_hdmi_monitor(edid);
+
+		/* keep the EDID as ELD for the audio subsystem */
+		drm_edid_to_eld(connector, edid);
+		priv->eld = connector->eld;
+
 		kfree(edid);
 	}
 
diff --git a/include/drm/i2c/tda998x.h b/include/drm/i2c/tda998x.h
index 0459931..64aaaa8 100644
--- a/include/drm/i2c/tda998x.h
+++ b/include/drm/i2c/tda998x.h
@@ -26,6 +26,7 @@ struct tda998x_encoder_params {
 	unsigned audio_sample_rate;
 };
 
+u8 *tda998x_audio_get_eld(struct i2c_client *client);
 void tda998x_audio_update(struct i2c_client *client,
 			int format,
 			int port);
diff --git a/sound/soc/codecs/tda998x.c b/sound/soc/codecs/tda998x.c
index d724f7d..500ac61 100644
--- a/sound/soc/codecs/tda998x.c
+++ b/sound/soc/codecs/tda998x.c
@@ -91,10 +91,79 @@ static int tda_startup(struct snd_pcm_substream *substream,
 			struct snd_soc_dai *dai)
 {
 	struct tda_priv *priv = snd_soc_codec_get_drvdata(dai->codec);
+	u8 *eld = NULL;
+	static unsigned rates_mask[] = {
+		SNDRV_PCM_RATE_32000,
+		SNDRV_PCM_RATE_44100,
+		SNDRV_PCM_RATE_48000,
+		SNDRV_PCM_RATE_88200,
+		SNDRV_PCM_RATE_96000,
+		SNDRV_PCM_RATE_176400,
+		SNDRV_PCM_RATE_192000,
+	};
 
 	/* memorize the used DAI */
 	priv->dai_id = dai->id;
 
+	/* get the ELD from the tda998x driver */
+	if (!priv->i2c_client)
+		tda_get_encoder(priv);
+	if (priv->i2c_client)
+		eld = tda998x_audio_get_eld(priv->i2c_client);
+
+	/* adjust the hw params from the ELD (EDID) */
+	if (eld) {
+		struct snd_soc_dai_driver *dai_drv = dai->driver;
+		struct snd_soc_pcm_stream *stream = &dai_drv->playback;
+		u8 *sad;
+		int sad_count;
+		unsigned eld_ver, mnl, rates, rate_mask, i;
+		unsigned max_channels, fmt;
+		u64 formats;
+
+		eld_ver = eld[0] >> 3;
+		if (eld_ver != 2 && eld_ver != 31)
+			return 0;
+
+		mnl = eld[4] & 0x1f;
+		if (mnl > 16)
+			return 0;
+
+		sad_count = eld[5] >> 4;
+		sad = eld + 20 + mnl;
+
+		/* Start from the basic audio settings */
+		max_channels = 2;
+		rates = 0;
+		fmt = 0;
+		while (sad_count--) {
+			switch (sad[0] & 0x78) {
+			case 0x08: /* PCM */
+				max_channels = max(max_channels, (sad[0] & 7) + 1u);
+				rates |= sad[1];
+				fmt |= sad[2] & 0x07;
+				break;
+			}
+			sad += 3;
+		}
+
+		for (rate_mask = i = 0; i < ARRAY_SIZE(rates_mask); i++)
+			if (rates & 1 << i)
+				rate_mask |= rates_mask[i];
+		formats = 0;
+		if (fmt & 1)
+			formats |= SNDRV_PCM_FMTBIT_S16_LE;
+		if (fmt & 2)
+			formats |= SNDRV_PCM_FMTBIT_S20_3LE;
+		if (fmt & 4)
+			formats |= SNDRV_PCM_FMTBIT_S24_LE;
+
+		/* change the snd_soc_pcm_stream values of the driver */
+		stream->rates = rate_mask;
+		stream->channels_max = max_channels;
+		stream->formats = formats;
+	}
+
 	/* start the TDA998x audio */
 	return tda_start_stop(priv, 1);
 }
@@ -193,9 +262,17 @@ static const struct snd_soc_codec_driver soc_codec_tda998x = {
 
 static int tda998x_dev_probe(struct platform_device *pdev)
 {
+	struct snd_soc_dai_driver *dai_drv;
+
+	/* copy the DAI driver to a writable area */
+	dai_drv = devm_kzalloc(&pdev->dev, sizeof(tda998x_dai), GFP_KERNEL);
+	if (!dai_drv)
+		return -ENOMEM;
+	memcpy(dai_drv, tda998x_dai, sizeof(tda998x_dai));
+
 	return snd_soc_register_codec(&pdev->dev,
 				&soc_codec_tda998x,
-				tda998x_dai, ARRAY_SIZE(tda998x_dai));
+				dai_drv, ARRAY_SIZE(tda998x_dai));
 }
 
 static int tda998x_dev_remove(struct platform_device *pdev)
-- 
1.8.5.3