[PATCH] ASoC: imx-rpmsg: Add DSD format support with dynamic DAI format switching

[Chancel Liu]

Add hw_params callback to dynamically switch DAI format between I2S
and PDM based on audio stream format. When DSD formats are detected,
the DAI format is switched to PDM mode.

Signed-off-by: Chancel Liu <chancel.liu@xxxxxxx>
---
 sound/soc/fsl/imx-rpmsg.c | 48 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/sound/soc/fsl/imx-rpmsg.c b/sound/soc/fsl/imx-rpmsg.c
index 76a8e68c1b62..40e0043cfe15 100644
--- a/sound/soc/fsl/imx-rpmsg.c
+++ b/sound/soc/fsl/imx-rpmsg.c
@@ -30,6 +30,53 @@ static const struct snd_soc_dapm_widget imx_rpmsg_dapm_widgets[] = {
 	SND_SOC_DAPM_MIC("Main MIC", NULL),
 };
 
+static int imx_rpmsg_hw_params(struct snd_pcm_substream *substream,
+			       struct snd_pcm_hw_params *params)
+{
+	struct snd_soc_pcm_runtime *rtd = snd_soc_substream_to_rtd(substream);
+	struct snd_soc_dai *codec_dai = snd_soc_rtd_to_codec(rtd, 0);
+	struct snd_soc_dai *cpu_dai = snd_soc_rtd_to_cpu(rtd, 0);
+	snd_pcm_format_t format = params_format(params);
+	struct device *dev = rtd->card->dev;
+	unsigned int fmt = rtd->dai_link->dai_fmt;
+	bool format_is_dsd = false;
+	int ret;
+
+	switch (format) {
+	case SNDRV_PCM_FORMAT_DSD_U8:
+	case SNDRV_PCM_FORMAT_DSD_U16_LE:
+	case SNDRV_PCM_FORMAT_DSD_U16_BE:
+	case SNDRV_PCM_FORMAT_DSD_U32_LE:
+	case SNDRV_PCM_FORMAT_DSD_U32_BE:
+		format_is_dsd = true;
+		break;
+	default:
+		format_is_dsd = false;
+		break;
+	}
+
+	if (format_is_dsd)
+		fmt = (rtd->dai_link->dai_fmt & ~SND_SOC_DAIFMT_FORMAT_MASK) |
+		       SND_SOC_DAIFMT_PDM;
+
+	ret = snd_soc_dai_set_fmt(cpu_dai, fmt);
+	if (ret && ret != -ENOTSUPP) {
+		dev_err(dev, "failed to set cpu dai fmt: %d\n", ret);
+		return ret;
+	}
+	ret = snd_soc_dai_set_fmt(codec_dai, fmt);
+	if (ret && ret != -ENOTSUPP) {
+		dev_err(dev, "failed to set codec dai fmt: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct snd_soc_ops imx_rpmsg_ops = {
+	.hw_params = imx_rpmsg_hw_params,
+};
+
 static int imx_rpmsg_late_probe(struct snd_soc_card *card)
 {
 	struct imx_rpmsg *data = snd_soc_card_get_drvdata(card);
@@ -135,6 +182,7 @@ static int imx_rpmsg_probe(struct platform_device *pdev)
 	data->dai.dai_fmt = SND_SOC_DAIFMT_I2S |
 			    SND_SOC_DAIFMT_NB_NF |
 			    SND_SOC_DAIFMT_CBC_CFC;
+	data->dai.ops = &imx_rpmsg_ops;
 
 	/*
 	 * i.MX rpmsg sound cards work on codec slave mode. MCLK will be
-- 
2.50.1