ASoC: qcom: lpass-cpu: Fix pop noise during audio capture begin

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>

diff --git a/sound/soc/qcom/lpass-cpu.c b/sound/soc/qcom/lpass-cpu.c
index 28c7497..a6e95db 100644 (file)
--- 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 83b2e08..7f72214 100644 (file)
--- 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 */