Judy,
On Thu, Jun 3, 2021 at 8:08 AM Judy Hsiao <judyhsiao@xxxxxxxxxxxx> wrote:
>
> @@ -315,12 +353,54 @@ 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).
> + */
nit: there's usually a blank line between the variable declarations
and the first line of code, even if the first line of code is a
comment.
> + 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]) {
> + drvdata->mi2s_was_prepared[dai->driver->id] = true;
> + ret = clk_enable(drvdata->mi2s_bit_clk[id]);
> + if (ret) {
> + dev_err(dai->dev, "error in enabling mi2s bit clk: %d\n", ret);
> + clk_disable(drvdata->mi2s_osr_clk[id]);
Can you explain why this clk_disable() is here? Your function didn't
turn this clock on, so why should it be turning it off in the error
case?
> + drvdata->mi2s_was_prepared[dai->driver->id] = false;
> + return ret;
> + }
Why not put the `drvdata->mi2s_was_prepared[dai->driver->id] = true;`
_after_ you check for errors. Then you don't need to undo it in the
error case. I presume that your prepare() function isn't reentrant and
can't be called at the same time as your shutdown (right?).
Other than that, I don't have any objections to this patch anymore. I
probably won't add a formal "Reviewed-by", though, since I _really_
don't know anything about the issue at hand or the code. I just
stumbled upon this because I was getting the clock splat at bootup. If
someone feels like this needs me to spin up enough to understand /
really review this patch then please yell.
-Doug
