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[PATCH v3 7/7] ASoC: tas2770: expose SDOUT bus keeper via set_tdm_idle

James Calligeros posted 7 patches 1 month, 1 week ago
[PATCH v3 7/7] ASoC: tas2770: expose SDOUT bus keeper via set_tdm_idle
Posted by James Calligeros 1 month, 1 week ago 
TAS2770 includes a bus keeper which can be used to control the behaviour
of the SDOUT pin during specified TDM slots. The chip can either pull
the pin to ground, actively transmit zeroes, or keep the pin floating
(default/uninitialised behaviour).

Expose the bus keeper via the set_tdm_idle DAI op so that it can be
configured by consumers.

Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
---
 sound/soc/codecs/tas2770.c | 75 +++++++++++++++++++++++++
 sound/soc/codecs/tas2770.h | 12 ++++
 2 files changed, 87 insertions(+)

diff --git a/sound/soc/codecs/tas2770.c b/sound/soc/codecs/tas2770.c
index 6f878b01716f..d4d7d056141b 100644
--- a/sound/soc/codecs/tas2770.c
+++ b/sound/soc/codecs/tas2770.c
@@ -492,11 +492,86 @@ static int tas2770_set_dai_tdm_slot(struct snd_soc_dai *dai,
 	return 0;
 }
 
+static int tas2770_set_dai_tdm_idle(struct snd_soc_dai *dai,
+				    unsigned int tx_mask,
+				    unsigned int rx_mask,
+				    int tx_mode, int rx_mode)
+{
+	struct snd_soc_component *component = dai->component;
+	struct tas2770_priv *tas2770 = snd_soc_component_get_drvdata(component);
+	int ret;
+
+	/* We don't support setting anything for SDIN */
+	if (rx_mode)
+		return -EOPNOTSUPP;
+
+	if (tas2770->idle_tx_mode == tx_mode)
+		return 0;
+
+	switch (tx_mode) {
+	case SND_SOC_DAI_TDM_IDLE_PULLDOWN:
+		ret = snd_soc_component_update_bits(component, TAS2770_DIN_PD,
+						    TAS2770_DIN_PD_SDOUT,
+						    TAS2770_DIN_PD_SDOUT);
+		if (ret)
+			return ret;
+
+		break;
+	case SND_SOC_DAI_TDM_IDLE_ZERO:
+		ret = snd_soc_component_update_bits(component, TAS2770_TDM_CFG_REG4,
+						    TAS2770_TDM_CFG_REG4_TX_KEEPER,
+						    TAS2770_TDM_CFG_REG4_TX_KEEPER);
+		if (ret)
+			return ret;
+
+		ret = snd_soc_component_update_bits(component, TAS2770_TDM_CFG_REG4,
+						    TAS2770_TDM_CFG_REG4_TX_FILL, 0);
+		if (ret)
+			return ret;
+
+		break;
+	case SND_SOC_DAI_TDM_IDLE_HIZ:
+		ret = snd_soc_component_update_bits(component, TAS2770_TDM_CFG_REG4,
+						    TAS2770_TDM_CFG_REG4_TX_KEEPER,
+						    TAS2770_TDM_CFG_REG4_TX_KEEPER);
+		if (ret)
+			return ret;
+
+		ret = snd_soc_component_update_bits(component, TAS2770_TDM_CFG_REG4,
+						    TAS2770_TDM_CFG_REG4_TX_FILL,
+						    TAS2770_TDM_CFG_REG4_TX_FILL);
+		if (ret)
+			return ret;
+
+		break;
+	case SND_SOC_DAI_TDM_IDLE_OFF:
+		ret = snd_soc_component_update_bits(component, TAS2770_DIN_PD,
+						    TAS2770_DIN_PD_SDOUT, 0);
+		if (ret)
+			return ret;
+
+		ret = snd_soc_component_update_bits(component, TAS2770_TDM_CFG_REG4,
+						    TAS2770_TDM_CFG_REG4_TX_KEEPER, 0);
+		if (ret)
+			return ret;
+
+		break;
+
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	tas2770->idle_tx_mode = tx_mode;
+
+	return 0;
+}
+
 static const struct snd_soc_dai_ops tas2770_dai_ops = {
 	.mute_stream = tas2770_mute,
 	.hw_params  = tas2770_hw_params,
 	.set_fmt    = tas2770_set_fmt,
 	.set_tdm_slot = tas2770_set_dai_tdm_slot,
+	.set_tdm_idle = tas2770_set_dai_tdm_idle,
 	.no_capture_mute = 1,
 };
 
diff --git a/sound/soc/codecs/tas2770.h b/sound/soc/codecs/tas2770.h
index 3fd2e7003c50..102040b6bdf8 100644
--- a/sound/soc/codecs/tas2770.h
+++ b/sound/soc/codecs/tas2770.h
@@ -67,6 +67,14 @@
 #define TAS2770_TDM_CFG_REG3_RXS_SHIFT 0x4
 #define TAS2770_TDM_CFG_REG3_30_MASK  GENMASK(3, 0)
 #define TAS2770_TDM_CFG_REG3_30_SHIFT 0
+    /* TDM Configuration Reg4 */
+#define TAS2770_TDM_CFG_REG4  TAS2770_REG(0X0, 0x0E)
+#define TAS2770_TDM_CFG_REG4_TX_LSB_CFG BIT(7)
+#define TAS2770_TDM_CFG_REG4_TX_KEEPER_CFG BIT(6)
+#define TAS2770_TDM_CFG_REG4_TX_KEEPER BIT(5)
+#define TAS2770_TDM_CFG_REG4_TX_FILL BIT(4)
+#define TAS2770_TDM_CFG_REG4_TX_OFFSET_MASK GENMASK(3, 1)
+#define TAS2770_TDM_CFG_REG4_TX_EDGE_FALLING BIT(0)
     /* TDM Configuration Reg5 */
 #define TAS2770_TDM_CFG_REG5  TAS2770_REG(0X0, 0x0F)
 #define TAS2770_TDM_CFG_REG5_VSNS_MASK  BIT(6)
@@ -115,6 +123,9 @@
 #define TAS2770_TEMP_LSB  TAS2770_REG(0X0, 0x2A)
     /* Interrupt Configuration */
 #define TAS2770_INT_CFG  TAS2770_REG(0X0, 0x30)
+    /* Data In Pull-Down */
+#define TAS2770_DIN_PD  TAS2770_REG(0X0, 0x31)
+#define TAS2770_DIN_PD_SDOUT BIT(7)
     /* Misc IRQ */
 #define TAS2770_MISC_IRQ  TAS2770_REG(0X0, 0x32)
     /* Clock Configuration */
@@ -146,6 +157,7 @@ struct tas2770_priv {
 	int pdm_slot;
 	bool dac_powered;
 	bool unmuted;
+	int idle_tx_mode;
 };
 
 #endif /* __TAS2770__ */

-- 
2.53.0
Re: [PATCH v3 7/7] ASoC: tas2770: expose SDOUT bus keeper via set_tdm_idle
Posted by Mark Brown 1 month ago 
On Sun, Mar 01, 2026 at 06:05:26PM +1000, James Calligeros wrote:

> +static int tas2770_set_dai_tdm_idle(struct snd_soc_dai *dai,
> +				    unsigned int tx_mask,
> +				    unsigned int rx_mask,
> +				    int tx_mode, int rx_mode)
> +{

> +	switch (tx_mode) {
> +	case SND_SOC_DAI_TDM_IDLE_PULLDOWN:
> +		ret = snd_soc_component_update_bits(component, TAS2770_DIN_PD,
> +						    TAS2770_DIN_PD_SDOUT,
> +						    TAS2770_DIN_PD_SDOUT);
> +		if (ret)
> +			return ret;
> +
> +		break;

This and all the other cases only updates the bits it's specifically
setting for the mode, so _ZERO and _HIZ don't update the pull and this
doesn't update the _KEEP/_FILL settings.  Not sure how often anyone is
going to change this at runtime though.

> +	case SND_SOC_DAI_TDM_IDLE_OFF:
> +		ret = snd_soc_component_update_bits(component, TAS2770_DIN_PD,
> +						    TAS2770_DIN_PD_SDOUT, 0);
> +		if (ret)
> +			return ret;
> +
> +		ret = snd_soc_component_update_bits(component, TAS2770_TDM_CFG_REG4,
> +						    TAS2770_TDM_CFG_REG4_TX_KEEPER, 0);

Actually this does _KEEP but not _FILL.
Re: [PATCH v3 7/7] ASoC: tas2770: expose SDOUT bus keeper via set_tdm_idle
Posted by James Calligeros 1 month ago 
On Friday, 13 March 2026 12:33:05 am Australian Eastern Standard Time Mark Brown wrote:
> On Sun, Mar 01, 2026 at 06:05:26PM +1000, James Calligeros wrote:
> > +static int tas2770_set_dai_tdm_idle(struct snd_soc_dai *dai,
> > +				    unsigned int tx_mask,
> > +				    unsigned int rx_mask,
> > +				    int tx_mode, int rx_mode)
> > +{
> > 
> > +	switch (tx_mode) {
> > +	case SND_SOC_DAI_TDM_IDLE_PULLDOWN:
> > +		ret = snd_soc_component_update_bits(component, TAS2770_DIN_PD,
> > +						    TAS2770_DIN_PD_SDOUT,
> > +						    TAS2770_DIN_PD_SDOUT);
> > +		if (ret)
> > +			return ret;
> > +
> > +		break;
> 
> This and all the other cases only updates the bits it's specifically
> setting for the mode, so _ZERO and _HIZ don't update the pull and this
> doesn't update the _KEEP/_FILL settings.  Not sure how often anyone is
> going to change this at runtime though.

I didn't notice any side effects caused by not explicitly turning off
the weak pulldown, but it makes sense to do if the consumer has asked
for a mode that is not pulldown.

> > +	case SND_SOC_DAI_TDM_IDLE_OFF:
> > +		ret = snd_soc_component_update_bits(component, TAS2770_DIN_PD,
> > +						    TAS2770_DIN_PD_SDOUT, 0);
> > +		if (ret)
> > +			return ret;
> > +
> > +		ret = snd_soc_component_update_bits(component, TAS2770_TDM_CFG_REG4,
> > +						    TAS2770_TDM_CFG_REG4_TX_KEEPER, 0);
> 
> Actually this does _KEEP but not _FILL.

_KEEPER is the important one. _FILL just controls the behaviour
of the bus keeper (zero or Hi-Z) when _KEEPER is set. If _KEEPER is
cleared, the bus keeper is turned off and the value of _FILL doesn't
matter.

Patchew 2.1-devel-ea86937

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