[v7] ASoC: qcom: lpass-cpu: Fix pop noise during audio capture begin
Srinivas Kandagatla
srinivas.kandagatla at linaro.org
Mon Jun 7 16:32:22 CEST 2021
On 04/06/2021 16:45, Judy Hsiao wrote:
> From: Srinivasa Rao Mandadapu <srivasam at codeaurora.org>
>
> 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.
>
> Co-developed-by: Judy Hsiao <judyhsiao at chromium.org>
> Signed-off-by: Judy Hsiao <judyhsiao at chromium.org>
> Signed-off-by: Srinivasa Rao Mandadapu <srivasam at codeaurora.org>
> (am from https://patchwork.kernel.org/patch/12276369/)
> (also found at https://lore.kernel.org/r/20210524142114.18676-1-srivasam@codeaurora.org)
>
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla at linaro.org>
> ---
> Changes Since V6:
> -- Removed clk_disable OSR clock in lpass_cpu_daiops_prepare error case as failure
> of prepare will result in calling shutdown which should take care of this.
> Changes Since V5:
> -- Fixed nit.
> -- Updated `mi2s_was_prepared[dai->driver->id] = true;` after checking for errors.
> Changes Since V4:
> -- Replaced the __clk_is_enabled(BCLK) check by the self maintained.
> mi2s_was_prepared bool state.
> -- Removed unrelated changes.
> -- Refined comments.
> Changes Since V3:
> -- Checked BCLK is off before enabling it in lpass_cpu_daiops_prepare as
> lpass_cpu_daiops_prepare can be called multiple times
> -- Checked BCLK is on before disabling it in lpass_cpu_daiops_shutdown to
> fix the WARN. It is because BCLK may not be enabled if
> lpass_cpu_daiops_prepare is not called before lpass_cpu_daiops_shutdown
> -- Added more comments
> Changes Since V2:
> -- Updated comments as per linux style
> -- Removed unrelated changes
> Changes Since V1:
> -- Enabled BCLK and LRCLK in dai ops prepare API instead of startup API
> -- Added comments
>
> 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 af8cb64924a0..647423a6cb57 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 */
>
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