ASoC: ti: davinci-i2s: Link free-run mode to SND_SOC_DAIFMT_[GATED/CONT]

McBSP has free-running mode where serial clocks continue to run during
emulation halts. This mode is always enabled by the driver.

Set free-running mode when SND_SOC_DAIFMT_CONT is selected by DAI
format, unset it when SND_SOC_DAIFMT_GATED is selected.

Signed-off-by: Bastien Curutchet <[e-mail]>
Acked-by: Peter Ujfalusi <[e-mail]>
Link: https://msgid.link/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/ti/davinci-i2s.c

···
 {
 	struct davinci_mcbsp_dev *dev = snd_soc_dai_get_drvdata(cpu_dai);
 	unsigned int pcr;
+	unsigned int spcr;
 	unsigned int srgr;
 	bool inv_fs = false;
 	/* Attention srgr is updated by hw_params! */
···
 		DAVINCI_MCBSP_SRGR_FWID(DEFAULT_BITPERSAMPLE - 1);
 
 	dev->fmt = fmt;
+
+	spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
+	switch (fmt & SND_SOC_DAIFMT_CLOCK_MASK) {
+	case SND_SOC_DAIFMT_CONT:
+		spcr |= DAVINCI_MCBSP_SPCR_FREE;
+		dev_dbg(dev->dev, "Free-running mode ON\n");
+		break;
+	case SND_SOC_DAIFMT_GATED:
+		spcr &= ~DAVINCI_MCBSP_SPCR_FREE;
+		dev_dbg(dev->dev, "Free-running mode OFF\n");
+		break;
+	default:
+		dev_err(dev->dev, "Invalid clock gating\n");
+		return -EINVAL;
+	}
+	davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
+
 	/* set master/slave audio interface */
 	switch (fmt & SND_SOC_DAIFMT_CLOCK_PROVIDER_MASK) {
 	case SND_SOC_DAIFMT_BP_FP:
···
 	/* general line settings */
 	spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
 	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
-		spcr |= DAVINCI_MCBSP_SPCR_RINTM(3) | DAVINCI_MCBSP_SPCR_FREE;
+		spcr |= DAVINCI_MCBSP_SPCR_RINTM(3);
 		davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
 	} else {
-		spcr |= DAVINCI_MCBSP_SPCR_XINTM(3) | DAVINCI_MCBSP_SPCR_FREE;
+		spcr |= DAVINCI_MCBSP_SPCR_XINTM(3);
 		davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
 	}