Re: [alsa-devel] [PATCH v6 1/2] ASoC:codecs: Add a transmitter interface to the HDMI CODEC CODEC

On 09/24/2014 10:49 AM, Jean-Francois Moine wrote:> The audio constraints of the HDMI interface are defined by the EDID

which is sent by the connected device.

The HDMI transmitters may have one or many audio sources.

This patch adds two functions to the HDMI CODEC:

• it updates the audio constraints from the EDID,
• it gives the audio source type to the HDMI transmitter on start of audio streaming.

Signed-off-by: Jean-Francois Moine moinejf@free.fr

include/sound/hdmi.h | 20 ++++++ sound/soc/codecs/hdmi.c | 174

++++++++++++++++++++++++++++++++++++++++++++++--

2 files changed, 188 insertions(+), 6 deletions(-) create mode 100644 include/sound/hdmi.h

diff --git a/include/sound/hdmi.h b/include/sound/hdmi.h new file mode 100644 index 0000000..49062c7 --- /dev/null +++ b/include/sound/hdmi.h @@ -0,0 +1,20 @@ +#ifndef SND_HDMI_H +#define SND_HDMI_H

+#include <sound/soc.h>

+/* platform_data */ +struct hdmi_data {

• int (*get_audio)(struct device *dev,

• 	 int *max_channels,
  

• 	 int *rate_mask,
  

• 	 int *fmt);
  

This looks good for the api to HDMI ASoC codec.

• void (*audio_switch)(struct device *dev,

• 	     int port_index,
  

• 	     unsigned sample_rate,
  

• 	     int sample_format);
  

I see nothing about selecting the i2s format. I do not know too much about tda998x registers but sii9022 can select left and right justified mode, bit-clock and frame-clock polarity etc. Should we need a callback that corresponds to snd_soc_dai_ops .set_fmt ?

SiI9022 also uses an external clock as some kind of reference for audio and that needs to be divided to right ballpark in relation sample-rate (I have no idea why this is, I am just talking about experience). Should we need callback that corresponds to snd_soc_dai_ops .set_sysclk?

Maybe the above two could also be left for later.

• int ndais;
• struct snd_soc_dai_driver *dais;
• struct snd_soc_codec_driver *driver;

+};

The need to include sound/soc.h is something I was trying to avoid in my early design for a similar generic HDMI ASoC codec. I came up with this requirement from Mark's comments about my OMAP HDMI audio patches. So the bellow suggestion are really up to Mark.

If I understand right, the need for ndais, dais, and driver is coming solely from spdif/i2s switching change. Since at least I am not aware of any other DAIs found in HDMI encoders, could we just give the info whether i2s and/or spdif is supporter with a simple bit-field or enum? The snd_soc_dai_driver and snd_soc_codec_driver definitions could then be all put to ASoC side of source tree.

I have also been wondering why we do not have SND_SOC_DAIFMT_SPDIF definition in sound/soc-dai.h. With that there would be no need to define two different dais for spdif and i2s. But this is more a suggestion for ASoC core future development. Because I do not currently have any HW to experiment with this the suggestion should probably be left only as a side note for now.

+#endif diff --git a/sound/soc/codecs/hdmi.c b/sound/soc/codecs/hdmi.c index 1087fd5..6ea2772 100644 --- a/sound/soc/codecs/hdmi.c +++ b/sound/soc/codecs/hdmi.c @@ -22,9 +22,146 @@ #include <sound/soc.h> #include <linux/of.h> #include <linux/of_device.h> +#include <sound/pcm_params.h> +#include <sound/hdmi.h>

#define DRV_NAME "hdmi-audio-codec"

+struct hdmi_priv {

• struct hdmi_data hdmi_data;
• struct snd_pcm_hw_constraint_list rate_constraints;

+};

+static int hdmi_dev_match(struct device *dev, void *data) +{

• return !strcmp(dev_name(dev), (char *) data);

+}

+/* get the codec device */ +static struct device *hdmi_get_cdev(struct device *dev) +{

• struct device *cdev;
• cdev = device_find_child(dev,

• 		 DRV_NAME,
  

• 		 hdmi_dev_match);
  

• if (!cdev)

• dev_err(dev, "Cannot get codec device");
  

• else

• put_device(cdev);
  

• return cdev;

+}

+static int hdmi_startup(struct snd_pcm_substream *substream,

• 	struct snd_soc_dai *dai)
  

+{

• struct snd_pcm_runtime *runtime = substream->runtime;
• struct device *cdev;
• struct hdmi_priv *priv;
• struct snd_pcm_hw_constraint_list *rate_constraints;
• int ret, max_channels, rate_mask, fmt;
• u64 formats;
• static const u32 hdmi_rates[] = {

• 32000, 44100, 48000, 88200, 96000, 176400, 192000
  

• };
• cdev = hdmi_get_cdev(dai->dev);
• if (!cdev)

• return -ENODEV;
  

• priv = dev_get_drvdata(cdev);
• /* get the EDID values and the rate constraints buffer */
• ret = priv->hdmi_data.get_audio(dai->dev,

• 			&max_channels, &rate_mask, &fmt);
  

• if (ret < 0)

• return ret;				/* no screen */
  

• /* convert the EDID values to audio constraints */
• rate_constraints = &priv->rate_constraints;
• rate_constraints->list = hdmi_rates;
• rate_constraints->count = ARRAY_SIZE(hdmi_rates);
• rate_constraints->mask = rate_mask;
• snd_pcm_hw_constraint_list(runtime, 0,

• 		   SNDRV_PCM_HW_PARAM_RATE,
  

• 		   rate_constraints);
  

• 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;
  

I think we should add here: formats |= SNDRV_PCM_FMTBIT_S24_3LE; and probably also formats |= SNDRV_PCM_FMTBIT_S32_LE;

The S24_3LE is equal to S24_LE at i2s level and the 32bit format would help to get better than 16bit audio working with if there is trouble supporting 24bit formats (like I have with wip sii9022 code). Both tda998x and sii9022 are able to play 32bit i2s audio just fine. The 8 least significant bits are naturally ignored, but we can set .sig_bits = 24 in snd_soc_pcm_stream.

• snd_pcm_hw_constraint_mask64(runtime,

• 		SNDRV_PCM_HW_PARAM_FORMAT,
  

• 		formats);
  

• snd_pcm_hw_constraint_minmax(runtime,

• 		SNDRV_PCM_HW_PARAM_CHANNELS,
  

• 		1, max_channels);
  

• return 0;

+}

+static int hdmi_hw_params(struct snd_pcm_substream *substream,

• 	  struct snd_pcm_hw_params *params,
  

• 	  struct snd_soc_dai *dai)
  

+{

• struct device *cdev;
• struct hdmi_priv *priv;
• cdev = hdmi_get_cdev(dai->dev);
• if (!cdev)

• return -ENODEV;
  

• priv = dev_get_drvdata(cdev);
• priv->hdmi_data.audio_switch(dai->dev, dai->id,

• 		     params_rate(params),
  

• 		     params_format(params));
  

• return 0;

+}

+static void hdmi_shutdown(struct snd_pcm_substream *substream,

• 	  struct snd_soc_dai *dai)
  

+{

• struct device *cdev;
• struct hdmi_priv *priv;
• cdev = hdmi_get_cdev(dai->dev);
• if (!cdev)

• return;
  

• priv = dev_get_drvdata(cdev);
• priv->hdmi_data.audio_switch(dai->dev, -1, 0, 0); /* stop */

+}

+static const struct snd_soc_dai_ops hdmi_ops = {

• .startup = hdmi_startup,
• .hw_params = hdmi_hw_params,
• .shutdown = hdmi_shutdown,

+};

+static int hdmi_codec_probe(struct snd_soc_codec *codec) +{

• struct hdmi_priv *priv;
• struct device *dev = codec->dev; /* encoder device */
• struct device *cdev; /* codec device */
• cdev = hdmi_get_cdev(dev);
• if (!cdev)

• return -ENODEV;
  

• /* allocate some memory to store

• * the encoder callback functions and the rate constraints */
  

• priv = devm_kzalloc(cdev, sizeof *priv, GFP_KERNEL);
• if (!priv)

• return -ENOMEM;
  

• dev_set_drvdata(cdev, priv);
• memcpy(&priv->hdmi_data, cdev->platform_data,

• 		sizeof priv->hdmi_data);
  

• return 0;

+}

• static const struct snd_soc_dapm_widget hdmi_widgets[] = { SND_SOC_DAPM_INPUT("RX"), SND_SOC_DAPM_OUTPUT("TX"),

@@ -77,13 +214,38 @@ static struct snd_soc_codec_driver hdmi_codec = { .num_dapm_routes = ARRAY_SIZE(hdmi_routes), };

-static int hdmi_codec_probe(struct platform_device *pdev) +static int hdmi_codec_dev_probe(struct platform_device *pdev) {

• return snd_soc_register_codec(&pdev->dev, &hdmi_codec,

• 	&hdmi_codec_dai, 1);
  

• struct hdmi_data *pdata = pdev->dev.platform_data;
• struct snd_soc_dai_driver *dais;
• struct snd_soc_codec_driver *driver;
• int i, ret;
• if (!pdata)

• return snd_soc_register_codec(&pdev->dev, &hdmi_codec,
  

• 				&hdmi_codec_dai, 1);
  

• /* creation from a video encoder as a child device */
• dais = devm_kmemdup(&pdev->dev,

• 	    pdata->dais,
  

• 	    sizeof *pdata->dais * pdata->ndais,
  

• 	    GFP_KERNEL);
  

• for (i = 0; i < pdata->ndais; i++)

• dais[i].ops = &hdmi_ops;
  

• driver = devm_kmemdup(&pdev->dev,

• 	    pdata->driver,
  

• 	    sizeof *pdata->driver,
  

• 	    GFP_KERNEL);
  

• driver->probe = hdmi_codec_probe;
• /* register the codec on the video encoder */
• ret = snd_soc_register_codec(pdev->dev.parent, driver,

• 			dais, pdata->ndais);
  

Registering the codec under the tda998x driver makes me wonder why would we need the a separate platform device in the first palce. At least it makes it possible to unify the old dummy HDMI codec with the new code, but I am not even sure if that makes eny sense.

Maybe we should have another dummy codec to be used in the situations where you really just need a dummy endpoint to satisfy ASoC. AFAIK the only setups that use the current hdmi codec are BBB HDMI audio and OMAP4+ HDMI audio, which both are currently broken in the upstream.

• return ret; }

-static int hdmi_codec_remove(struct platform_device *pdev) +static int hdmi_codec_dev_remove(struct platform_device *pdev) { snd_soc_unregister_codec(&pdev->dev); return 0; @@ -96,8 +258,8 @@ static struct platform_driver hdmi_codec_driver = { .of_match_table = of_match_ptr(hdmi_audio_codec_ids), },

• .probe = hdmi_codec_probe,
• .remove = hdmi_codec_remove,

• .probe = hdmi_codec_dev_probe,

• .remove = hdmi_codec_dev_remove, };

  module_platform_driver(hdmi_codec_driver);

What comes to compatibility to the old use of hdmi codec everything appears to be fine after this patch.

Best regards, Jyri