linux-kernel - Re: [linux-sunxi] [PATCH v5 12/15] ASoC: sun4i-i2s: Add multi-lane functionality

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Date:   Wed, 14 Aug 2019 10:27:26 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     linux-sunxi@...glegroups.com, codekipper@...il.com
Cc:     maxime.ripard@...e-electrons.com, wens@...e.org,
        linux-arm-kernel@...ts.infradead.org, lgirdwood@...il.com,
        broonie@...nel.org, linux-kernel@...r.kernel.org,
        alsa-devel@...a-project.org, be17068@...rbole.bo.it
Subject: Re: [linux-sunxi] [PATCH v5 12/15] ASoC: sun4i-i2s: Add multi-lane functionality

Hi!

Dne sreda, 14. avgust 2019 ob 08:08:51 CEST je codekipper@...il.com 
napisal(a):
> From: Marcus Cooper <codekipper@...il.com>
> 
> The i2s block supports multi-lane i2s output however this functionality
> is only possible in earlier SoCs where the pins are exposed and for
> the i2s block used for HDMI audio on the later SoCs.
> 
> To enable this functionality, an optional property has been added to
> the bindings.
> 
> Signed-off-by: Marcus Cooper <codekipper@...il.com>
> ---
>  sound/soc/sunxi/sun4i-i2s.c | 28 +++++++++++++++++++++++++---
>  1 file changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
> index a8d98696fe7c..a020c3b372a8 100644
> --- a/sound/soc/sunxi/sun4i-i2s.c
> +++ b/sound/soc/sunxi/sun4i-i2s.c
> @@ -23,7 +23,7 @@
> 
>  #define SUN4I_I2S_CTRL_REG		0x00
>  #define SUN4I_I2S_CTRL_SDO_EN_MASK		GENMASK(11, 8)
> -#define SUN4I_I2S_CTRL_SDO_EN(sdo)			BIT(8 + 
(sdo))
> +#define SUN4I_I2S_CTRL_SDO_EN(lines)		(((1 << lines) - 1) 
<< 8)
>  #define SUN4I_I2S_CTRL_MODE_MASK		BIT(5)
>  #define SUN4I_I2S_CTRL_MODE_SLAVE			(1 << 5)
>  #define SUN4I_I2S_CTRL_MODE_MASTER			(0 << 5)
> @@ -614,6 +614,7 @@ static int sun4i_i2s_hw_params(struct snd_pcm_substream
> *substream, struct sun4i_i2s *i2s = snd_soc_dai_get_drvdata(dai);
>  	int sr, wss, channels;
>  	u32 width;
> +	int lines;
> 
>  	channels = params_channels(params);
>  	if (channels != 2) {
> @@ -622,6 +623,13 @@ static int sun4i_i2s_hw_params(struct snd_pcm_substream
> *substream, return -EINVAL;
>  	}
> 
> +	lines = (channels + 1) / 2;
> +
> +	/* Enable the required output lines */
> +	regmap_update_bits(i2s->regmap, SUN4I_I2S_CTRL_REG,
> +			   SUN4I_I2S_CTRL_SDO_EN_MASK,
> +			   SUN4I_I2S_CTRL_SDO_EN(lines));

As Maxime said before, this doesn't work for TDM. Maybe we can skip this for 
now, until we agree on method how to describe channel allocation?

> +
>  	if (i2s->variant->has_chcfg) {
>  		regmap_update_bits(i2s->regmap, SUN8I_I2S_CHAN_CFG_REG,
>  				   
SUN8I_I2S_CHAN_CFG_TX_SLOT_NUM_MASK,
> @@ -1389,9 +1397,10 @@ static int sun4i_i2s_init_regmap_fields(struct device
> *dev, static int sun4i_i2s_probe(struct platform_device *pdev)
>  {
>  	struct sun4i_i2s *i2s;
> +	struct snd_soc_dai_driver *soc_dai;
>  	struct resource *res;
>  	void __iomem *regs;
> -	int irq, ret;
> +	int irq, ret, val;
> 
>  	i2s = devm_kzalloc(&pdev->dev, sizeof(*i2s), GFP_KERNEL);
>  	if (!i2s)
> @@ -1456,6 +1465,19 @@ static int sun4i_i2s_probe(struct platform_device
> *pdev) i2s->capture_dma_data.addr = res->start + SUN4I_I2S_FIFO_RX_REG;
> i2s->capture_dma_data.maxburst = 8;
> 
> +	soc_dai = devm_kmemdup(&pdev->dev, &sun4i_i2s_dai,
> +			       sizeof(*soc_dai), GFP_KERNEL);
> +	if (!soc_dai) {
> +		ret = -ENOMEM;
> +		goto err_pm_disable;
> +	}
> +
> +	if (!of_property_read_u32(pdev->dev.of_node,
> +				  "allwinner,playback-channels", 
&val)) {
> +		if (val >= 2 && val <= 8)
> +			soc_dai->playback.channels_max = val;
> +	}
> +

Rather than inventing new DT properties, I would rather have multiple 
snd_soc_dai_driver structures, depending on capabilities of that particular 
I2S block. That way we avoid some boilerplate code as can be seen here and 
it's IMO more transparent.

In this case, I would make another snd_soc_dai_driver struct for H3, which has 
channel_max property set to 8 and from patch 14, additional supported formats.

Best regards,
Jernej

>  	pm_runtime_enable(&pdev->dev);
>  	if (!pm_runtime_enabled(&pdev->dev)) {
>  		ret = sun4i_i2s_runtime_resume(&pdev->dev);
> @@ -1465,7 +1487,7 @@ static int sun4i_i2s_probe(struct platform_device
> *pdev)
> 
>  	ret = devm_snd_soc_register_component(&pdev->dev,
>  					      
&sun4i_i2s_component,
> -					      &sun4i_i2s_dai, 
1);
> +					      soc_dai, 1);
>  	if (ret) {
>  		dev_err(&pdev->dev, "Could not register DAI\n");
>  		goto err_suspend;