Re: [PATCH v1 3/4] ASoC: Intel: bytcr_rt5651: use devm_clk_get_optional() for mclk

Pierre-Louis Bossart
2021-10-06T16:13:52Z

On 10/6/21 10:04 AM, Andy Shevchenko wrote:
> The devm_clk_get_optional() helper returns NULL when devm_clk_get()
> returns -ENOENT. This makes things slightly cleaner. The added benefit
> is mostly cosmetic.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> sound/soc/intel/boards/bytcr_rt5651.c | 69 ++++++++++++---------------
> 1 file changed, 30 insertions(+), 39 deletions(-)
>
> diff --git a/sound/soc/intel/boards/bytcr_rt5651.c b/sound/soc/intel/boards/bytcr_rt5651.c
> index 36f63516f0cb..28c561302e69 100644
> --- a/sound/soc/intel/boards/bytcr_rt5651.c
> +++ b/sound/soc/intel/boards/bytcr_rt5651.c
> @@ -188,13 +188,10 @@ static int platform_clock_control(struct snd_soc_dapm_widget *w,
> }
>
> if (SND_SOC_DAPM_EVENT_ON(event)) {
> - if (byt_rt5651_quirk & BYT_RT5651_MCLK_EN) {
> - ret = clk_prepare_enable(priv->mclk);
> - if (ret < 0) {
> - dev_err(card->dev,
> - "could not configure MCLK state");
> - return ret;
> - }
> + ret = clk_prepare_enable(priv->mclk);
> + if (ret < 0) {
> + dev_err(card->dev, "could not configure MCLK state");
> + return ret;
> }

I don't get why you removed the test on the BYT_RT5651_MCLK_EN quirk,
see below it was designed as a fall-back mode. We don't want to return
an error when we know the clock is not present/desired.

> ret = byt_rt5651_prepare_and_enable_pll1(codec_dai, 48000, 50);
> } else {
> @@ -207,8 +204,7 @@ static int platform_clock_control(struct snd_soc_dapm_widget *w,
> 48000 * 512,
> SND_SOC_CLOCK_IN);
> if (!ret)
> - if (byt_rt5651_quirk & BYT_RT5651_MCLK_EN)
> - clk_disable_unprepare(priv->mclk);
> + clk_disable_unprepare(priv->mclk);
> }
>
> if (ret < 0) {
> @@ -629,29 +625,25 @@ static int byt_rt5651_init(struct snd_soc_pcm_runtime *runtime)
> return ret;
> }
>
> - if (byt_rt5651_quirk & BYT_RT5651_MCLK_EN) {
> - /*
> - * The firmware might enable the clock at
> - * boot (this information may or may not
> - * be reflected in the enable clock register).
> - * To change the rate we must disable the clock
> - * first to cover these cases. Due to common
> - * clock framework restrictions that do not allow
> - * to disable a clock that has not been enabled,
> - * we need to enable the clock first.
> - */
> - ret = clk_prepare_enable(priv->mclk);
> - if (!ret)
> - clk_disable_unprepare(priv->mclk);
> + /*
> + * The firmware might enable the clock at boot (this information
> + * may or may not be reflected in the enable clock register).
> + * To change the rate we must disable the clock first to cover
> + * these cases. Due to common clock framework restrictions that
> + * do not allow to disable a clock that has not been enabled,
> + * we need to enable the clock first.
> + */
> + ret = clk_prepare_enable(priv->mclk);
> + if (!ret)
> + clk_disable_unprepare(priv->mclk);
>
> - if (byt_rt5651_quirk & BYT_RT5651_MCLK_25MHZ)
> - ret = clk_set_rate(priv->mclk, 25000000);
> - else
> - ret = clk_set_rate(priv->mclk, 19200000);
> + if (byt_rt5651_quirk & BYT_RT5651_MCLK_25MHZ)
> + ret = clk_set_rate(priv->mclk, 25000000);
> + else
> + ret = clk_set_rate(priv->mclk, 19200000);
>
> - if (ret)
> - dev_err(card->dev, "unable to set MCLK rate\n");
> - }
> + if (ret)
> + dev_err(card->dev, "unable to set MCLK rate\n");

same here, why was the quirk removed?

>
> report = 0;
> if (BYT_RT5651_JDSRC(byt_rt5651_quirk))
> @@ -1064,21 +1056,20 @@ static int snd_byt_rt5651_mc_probe(struct platform_device *pdev)
> byt_rt5651_dais[dai_index].cpus->dai_name = "ssp0-port";
>
> if (byt_rt5651_quirk & BYT_RT5651_MCLK_EN) {
> - priv->mclk = devm_clk_get(dev, "pmc_plt_clk_3");
> + priv->mclk = devm_clk_get_optional(dev, "pmc_plt_clk_3");
> if (IS_ERR(priv->mclk)) {
> ret_val = PTR_ERR(priv->mclk);
> dev_err(dev,
> "Failed to get MCLK from pmc_plt_clk_3: %d\n",
> ret_val);
> - /*
> - * Fall back to bit clock usage for -ENOENT (clock not
> - * available likely due to missing dependencies), bail
> - * for all other errors, including -EPROBE_DEFER
> - */
> - if (ret_val != -ENOENT)
> - goto err;
> - byt_rt5651_quirk &= ~BYT_RT5651_MCLK_EN;
> + goto err;
> }
> + /*
> + * Fall back to bit clock usage when clock is not
> + * available likely due to missing dependencies.
> + */
> + if (!priv->mclk)
> + byt_rt5651_quirk &= ~BYT_RT5651_MCLK_EN;

that part in the probe looks fine, but the changes above are controversial.

> }
>
> snprintf(byt_rt5651_components, sizeof(byt_rt5651_components),
>