Re: [PATCH] ASoC: ti: Allocate dais dynamically for TDM and audio graph card

["Péter Ujfalusi" <peter.ujfalusi@gmail.com>]

Hi Pavel,

On 1/24/21 11:27 AM, Pavel Machek wrote:
> From: Tony Lindgren <tony@atomide.com>
> 
> We can have multiple connections on a single McBSP instance configured
> with audio graph card when using TDM (Time Division Multiplexing). Let's
> allow that by configuring dais dynamically.

Still we have _one_ DAI per McBSP. TDM slots are not DAIs.

> See Documentation/devicetree/bindings/sound/audio-graph-card.txt and
> Documentation/devicetree/bindings/graph.txt for more details for
> multiple endpoints.

Documentation/devicetree/bindings/sound/audio-graph-card.yaml
Documentation/devicetree/bindings/sound/audio-graph.yaml

However the schemas does not provide too much insight (the txts were a 
bit more verbose).

> I've tested this with droid4 where cpcap pmic and modem voice are both
> both wired to mcbsp3. I've also tested this on droid4 both with and
> without the pending modem audio codec driver that is waiting for n_gsm
> serdev dependencies to clear.
 >
> Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
> Cc: Arthur D. <spinal.by@gmail.com>
> Cc: Jarkko Nikula <jarkko.nikula@bitmer.com>
> Cc: Merlijn Wajer <merlijn@wizzup.org>
> Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
> Cc: Sebastian Reichel <sre@kernel.org>
> Signed-off-by: Tony Lindgren <tony@atomide.com>
> Signed-off-by: Pavel Machek <pavel@ucw.cz>
> 
> ---
>   sound/soc/ti/omap-mcbsp-priv.h |  2 ++
>   sound/soc/ti/omap-mcbsp.c      | 76 +++++++++++++++++++++++++++++-------------
>   2 files changed, 55 insertions(+), 23 deletions(-)
> 
> diff --git a/sound/soc/ti/omap-mcbsp-priv.h b/sound/soc/ti/omap-mcbsp-priv.h
> index 7865cda4bf0a..9464f5d35822 100644
> --- a/sound/soc/ti/omap-mcbsp-priv.h
> +++ b/sound/soc/ti/omap-mcbsp-priv.h
> @@ -262,6 +262,8 @@ struct omap_mcbsp {
>   	struct omap_mcbsp_platform_data *pdata;
>   	struct omap_mcbsp_st_data *st_data;
>   	struct omap_mcbsp_reg_cfg cfg_regs;
> +	struct snd_soc_dai_driver *dais;
> +	int dai_count;
>   	struct snd_dmaengine_dai_dma_data dma_data[2];
>   	unsigned int dma_req[2];
>   	int dma_op_mode;
> diff --git a/sound/soc/ti/omap-mcbsp.c b/sound/soc/ti/omap-mcbsp.c
> index 6025b30bbe77..189a6461b671 100644
> --- a/sound/soc/ti/omap-mcbsp.c
> +++ b/sound/soc/ti/omap-mcbsp.c
> @@ -14,6 +14,7 @@
>   #include <linux/pm_runtime.h>
>   #include <linux/of.h>
>   #include <linux/of_device.h>
> +#include <linux/of_graph.h>
>   #include <sound/core.h>
>   #include <sound/pcm.h>
>   #include <sound/pcm_params.h>
> @@ -1299,23 +1300,53 @@ static int omap_mcbsp_remove(struct snd_soc_dai *dai)
>   	return 0;
>   }
>   
> -static struct snd_soc_dai_driver omap_mcbsp_dai = {
> -	.probe = omap_mcbsp_probe,
> -	.remove = omap_mcbsp_remove,
> -	.playback = {
> -		.channels_min = 1,
> -		.channels_max = 16,
> -		.rates = OMAP_MCBSP_RATES,
> -		.formats = SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S32_LE,
> -	},
> -	.capture = {
> -		.channels_min = 1,
> -		.channels_max = 16,
> -		.rates = OMAP_MCBSP_RATES,
> -		.formats = SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S32_LE,
> -	},
> -	.ops = &mcbsp_dai_ops,
> -};
> +static int omap_mcbsp_init_dais(struct omap_mcbsp *mcbsp)
> +{
> +	struct device_node *np = mcbsp->dev->of_node;
> +	int i;
> +
> +	if (np)
> +		mcbsp->dai_count = of_graph_get_endpoint_count(np);
> +
> +	if (!mcbsp->dai_count)
> +		mcbsp->dai_count = 1;
> +
> +	mcbsp->dais = devm_kcalloc(mcbsp->dev, mcbsp->dai_count,
> +				   sizeof(*mcbsp->dais), GFP_KERNEL);
> +	if (!mcbsp->dais)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < mcbsp->dai_count; i++) {
> +		struct snd_soc_dai_driver *dai = &mcbsp->dais[i];
> +
> +		dai->name = devm_kasprintf(mcbsp->dev, GFP_KERNEL, "%s-dai%i",
> +					   dev_name(mcbsp->dev), i);
> +
> +		if (i == 0) {
> +			dai->probe = omap_mcbsp_probe;
> +			dai->remove = omap_mcbsp_remove;
> +			dai->ops = &mcbsp_dai_ops;
> +		}

You are effectively creating extra dummy-dais (no ops), but naming them 
as McBSP.
The dummy-dais will only work if the real dai is in use and the dai link 
which contains the real dai must be configured (TDM slots, format, 
channels) to accomodate the link which contains the dummy-dai.

The idea did not aged well for me ;)
It still looks and sounds like a hack to model the TDM slots on a single 
DAI as multiple DAIs just to satisfy a generic binding which is not 
aimed to satisfy the droid4 setup (which is far from anything simple).

> +		dai->playback.channels_min = 1;
> +		dai->playback.channels_max = 16;
> +		dai->playback.rates = OMAP_MCBSP_RATES;
> +		if (mcbsp->pdata->reg_size == 2)
> +			dai->playback.formats = SNDRV_PCM_FMTBIT_S16_LE;
> +		else
> +			dai->playback.formats = SNDRV_PCM_FMTBIT_S16_LE |
> +						SNDRV_PCM_FMTBIT_S32_LE;
> +		dai->capture.channels_min = 1;
> +		dai->capture.channels_max = 16;
> +		dai->capture.rates = OMAP_MCBSP_RATES;
> +		if (mcbsp->pdata->reg_size == 2)
> +			dai->capture.formats = SNDRV_PCM_FMTBIT_S16_LE;
> +		else
> +			dai->capture.formats = SNDRV_PCM_FMTBIT_S16_LE |
> +					       SNDRV_PCM_FMTBIT_S32_LE;
> +	}
> +
> +	return 0;
> +}
>   
>   static const struct snd_soc_component_driver omap_mcbsp_component = {
>   	.name		= "omap-mcbsp",
> @@ -1404,18 +1435,17 @@ static int asoc_mcbsp_probe(struct platform_device *pdev)
>   	mcbsp->dev = &pdev->dev;
>   	platform_set_drvdata(pdev, mcbsp);
>   
> -	ret = omap_mcbsp_init(pdev);
> +	ret = omap_mcbsp_init_dais(mcbsp);
>   	if (ret)
>   		return ret;
>   
> -	if (mcbsp->pdata->reg_size == 2) {
> -		omap_mcbsp_dai.playback.formats = SNDRV_PCM_FMTBIT_S16_LE;
> -		omap_mcbsp_dai.capture.formats = SNDRV_PCM_FMTBIT_S16_LE;
> -	}
> +	ret = omap_mcbsp_init(pdev);
> +	if (ret)
> +		return ret;
>   
>   	ret = devm_snd_soc_register_component(&pdev->dev,
>   					      &omap_mcbsp_component,
> -					      &omap_mcbsp_dai, 1);
> +					      mcbsp->dais, mcbsp->dai_count);
>   	if (ret)
>   		return ret;
>   
> 

-- 
Péter