[PATCH AUTOSEL 5.12 23/33] ASoC: qcom: lpass-cpu: Fix pop noise during audio capture begin

Sasha Levin
2021-06-15T15:49:46Z

From: Srinivasa Rao Mandadapu <srivasam@codeaurora.org>

[ Upstream commit c8a4556d98510ca05bad8d02265a4918b03a8c0b ]

This patch fixes PoP noise of around 15ms observed during audio
capture begin.
Enables BCLK and LRCLK in snd_soc_dai_ops prepare call for
introducing some delay before capture start.

(am from https://patchwork.kernel.org/patch/12276369/)
(also found at https://lore.kernel.org/r/20210524142114.18676-1-srivasam@codeaurora.org)

Co-developed-by: Judy Hsiao <judyhsiao@chromium.org>
Signed-off-by: Judy Hsiao <judyhsiao@chromium.org>
Signed-off-by: Srinivasa Rao Mandadapu <srivasam@codeaurora.org>
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20210604154545.1198337-1-judyhsiao@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/soc/qcom/lpass-cpu.c | 79 ++++++++++++++++++++++++++++++++++++++
sound/soc/qcom/lpass.h | 4 ++
2 files changed, 83 insertions(+)

diff --git a/sound/soc/qcom/lpass-cpu.c b/sound/soc/qcom/lpass-cpu.c
index 936384a94f25..74d3d8c58608 100644
--- a/sound/soc/qcom/lpass-cpu.c
+++ b/sound/soc/qcom/lpass-cpu.c
@@ -93,8 +93,30 @@ static void lpass_cpu_daiops_shutdown(struct snd_pcm_substream *substream,
struct snd_soc_dai *dai)
{
struct lpass_data *drvdata = snd_soc_dai_get_drvdata(dai);
+ struct lpaif_i2sctl *i2sctl = drvdata->i2sctl;
+ unsigned int id = dai->driver->id;

clk_disable_unprepare(drvdata->mi2s_osr_clk[dai->driver->id]);
+ /*
+ * Ensure LRCLK is disabled even in device node validation.
+ * Will not impact if disabled in lpass_cpu_daiops_trigger()
+ * suspend.
+ */
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+ regmap_fields_write(i2sctl->spken, id, LPAIF_I2SCTL_SPKEN_DISABLE);
+ else
+ regmap_fields_write(i2sctl->micen, id, LPAIF_I2SCTL_MICEN_DISABLE);
+
+ /*
+ * BCLK may not be enabled if lpass_cpu_daiops_prepare is called before
+ * lpass_cpu_daiops_shutdown. It's paired with the clk_enable in
+ * lpass_cpu_daiops_prepare.
+ */
+ if (drvdata->mi2s_was_prepared[dai->driver->id]) {
+ drvdata->mi2s_was_prepared[dai->driver->id] = false;
+ clk_disable(drvdata->mi2s_bit_clk[dai->driver->id]);
+ }
+
clk_unprepare(drvdata->mi2s_bit_clk[dai->driver->id]);
}

@@ -275,6 +297,18 @@ static int lpass_cpu_daiops_trigger(struct snd_pcm_substream *substream,
case SNDRV_PCM_TRIGGER_START:
case SNDRV_PCM_TRIGGER_RESUME:
case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+ /*
+ * Ensure lpass BCLK/LRCLK is enabled during
+ * device resume as lpass_cpu_daiops_prepare() is not called
+ * after the device resumes. We don't check mi2s_was_prepared before
+ * enable/disable BCLK in trigger events because:
+ * 1. These trigger events are paired, so the BCLK
+ * enable_count is balanced.
+ * 2. the BCLK can be shared (ex: headset and headset mic),
+ * we need to increase the enable_count so that we don't
+ * turn off the shared BCLK while other devices are using
+ * it.
+ */
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
ret = regmap_fields_write(i2sctl->spken, id,
LPAIF_I2SCTL_SPKEN_ENABLE);
@@ -296,6 +330,10 @@ static int lpass_cpu_daiops_trigger(struct snd_pcm_substream *substream,
case SNDRV_PCM_TRIGGER_STOP:
case SNDRV_PCM_TRIGGER_SUSPEND:
case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+ /*
+ * To ensure lpass BCLK/LRCLK is disabled during
+ * device suspend.
+ */
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
ret = regmap_fields_write(i2sctl->spken, id,
LPAIF_I2SCTL_SPKEN_DISABLE);
@@ -315,12 +353,53 @@ static int lpass_cpu_daiops_trigger(struct snd_pcm_substream *substream,
return ret;
}

+static int lpass_cpu_daiops_prepare(struct snd_pcm_substream *substream,
+ struct snd_soc_dai *dai)
+{
+ struct lpass_data *drvdata = snd_soc_dai_get_drvdata(dai);
+ struct lpaif_i2sctl *i2sctl = drvdata->i2sctl;
+ unsigned int id = dai->driver->id;
+ int ret;
+
+ /*
+ * Ensure lpass BCLK/LRCLK is enabled bit before playback/capture
+ * data flow starts. This allows other codec to have some delay before
+ * the data flow.
+ * (ex: to drop start up pop noise before capture starts).
+ */
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+ ret = regmap_fields_write(i2sctl->spken, id, LPAIF_I2SCTL_SPKEN_ENABLE);
+ else
+ ret = regmap_fields_write(i2sctl->micen, id, LPAIF_I2SCTL_MICEN_ENABLE);
+
+ if (ret) {
+ dev_err(dai->dev, "error writing to i2sctl reg: %d\n", ret);
+ return ret;
+ }
+
+ /*
+ * Check mi2s_was_prepared before enabling BCLK as lpass_cpu_daiops_prepare can
+ * be called multiple times. It's paired with the clk_disable in
+ * lpass_cpu_daiops_shutdown.
+ */
+ if (!drvdata->mi2s_was_prepared[dai->driver->id]) {
+ ret = clk_enable(drvdata->mi2s_bit_clk[id]);
+ if (ret) {
+ dev_err(dai->dev, "error in enabling mi2s bit clk: %d\n", ret);
+ return ret;
+ }
+ drvdata->mi2s_was_prepared[dai->driver->id] = true;
+ }
+ return 0;
+}
+
const struct snd_soc_dai_ops asoc_qcom_lpass_cpu_dai_ops = {
.set_sysclk = lpass_cpu_daiops_set_sysclk,
.startup = lpass_cpu_daiops_startup,
.shutdown = lpass_cpu_daiops_shutdown,
.hw_params = lpass_cpu_daiops_hw_params,
.trigger = lpass_cpu_daiops_trigger,
+ .prepare = lpass_cpu_daiops_prepare,
};
EXPORT_SYMBOL_GPL(asoc_qcom_lpass_cpu_dai_ops);

diff --git a/sound/soc/qcom/lpass.h b/sound/soc/qcom/lpass.h
index 83b2e08ade06..7f72214404ba 100644
--- a/sound/soc/qcom/lpass.h
+++ b/sound/soc/qcom/lpass.h
@@ -67,6 +67,10 @@ struct lpass_data {
/* MI2S SD lines to use for playback/capture */
unsigned int mi2s_playback_sd_mode[LPASS_MAX_MI2S_PORTS];
unsigned int mi2s_capture_sd_mode[LPASS_MAX_MI2S_PORTS];
+
+ /* The state of MI2S prepare dai_ops was called */
+ bool mi2s_was_prepared[LPASS_MAX_MI2S_PORTS];
+
int hdmi_port_enable;

/* low-power audio interface (LPAIF) registers */
--
2.30.2