[PATCH v4 15/21] ASoC: fsl_micfil: simplify clock setting

[Shengjiu Wang]

On Thu, Apr 7, 2022 at 4:49 PM Sascha Hauer <s.hauer at pengutronix.de> wrote:

> The reference manual has this for calculating the micfil internal clock
> divider:
>
>          MICFIL Clock rate
> clkdiv = -----------------
>          8 * OSR * outrate
>
> (with OSR == Oversampling Rate, outrate == output sample rate)
>
> The driver first sets the MICFIL Clock rate to (outrate * 1024) and then
> calculates back the clkdiv value from the above calculation.
>
> Simplify this by using a fixed clkdiv value of 8 and set the MICFIL
> Clock rate to (outrate * clkdiv * OSR * 8).
>
> While at it drop disabling the clock before setting its rate. The MICFIL
> module is disabled when the rate is changed and it is also resetted
> before it is started again, so I doubt it's necessary to disable the
> clock.
>
> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
>

Acked-by: Shengjiu Wang <shengjiu.wang at gmail.com>

Best regards
wang shengjiu

> ---
>
> Notes:
>     Changes since v3:
>     - Don't use uninitialized and no longer present struct fsl_micfil::osr
>
>  sound/soc/fsl/fsl_micfil.c | 45 ++++----------------------------------
>  1 file changed, 4 insertions(+), 41 deletions(-)
>
> diff --git a/sound/soc/fsl/fsl_micfil.c b/sound/soc/fsl/fsl_micfil.c
> index 3ddc988b4fe65..4d8dfb2c22290 100644
> --- a/sound/soc/fsl/fsl_micfil.c
> +++ b/sound/soc/fsl/fsl_micfil.c
> @@ -110,19 +110,6 @@ static const struct snd_kcontrol_new
> fsl_micfil_snd_controls[] = {
>                      snd_soc_get_enum_double, snd_soc_put_enum_double),
>  };
>
> -static inline int get_clk_div(struct fsl_micfil *micfil,
> -                             unsigned int rate)
> -{
> -       long mclk_rate;
> -       int clk_div;
> -
> -       mclk_rate = clk_get_rate(micfil->mclk);
> -
> -       clk_div = mclk_rate / (rate * MICFIL_OSR_DEFAULT * 8);
> -
> -       return clk_div;
> -}
> -
>  /* The SRES is a self-negated bit which provides the CPU with the
>   * capability to initialize the PDM Interface module through the
>   * slave-bus interface. This bit always reads as zero, and this
> @@ -146,24 +133,6 @@ static int fsl_micfil_reset(struct device *dev)
>         return 0;
>  }
>
> -static int fsl_micfil_set_mclk_rate(struct fsl_micfil *micfil,
> -                                   unsigned int freq)
> -{
> -       struct device *dev = &micfil->pdev->dev;
> -       int ret;
> -
> -       clk_disable_unprepare(micfil->mclk);
> -
> -       ret = clk_set_rate(micfil->mclk, freq * 1024);
> -       if (ret)
> -               dev_warn(dev, "failed to set rate (%u): %d\n",
> -                        freq * 1024, ret);
> -
> -       clk_prepare_enable(micfil->mclk);
> -
> -       return ret;
> -}
> -
>  static int fsl_micfil_startup(struct snd_pcm_substream *substream,
>                               struct snd_soc_dai *dai)
>  {
> @@ -237,13 +206,12 @@ static int fsl_micfil_trigger(struct
> snd_pcm_substream *substream, int cmd,
>  static int fsl_set_clock_params(struct device *dev, unsigned int rate)
>  {
>         struct fsl_micfil *micfil = dev_get_drvdata(dev);
> -       int clk_div;
> +       int clk_div = 8;
>         int ret;
>
> -       ret = fsl_micfil_set_mclk_rate(micfil, rate);
> -       if (ret < 0)
> -               dev_err(dev, "failed to set mclk[%lu] to rate %u\n",
> -                       clk_get_rate(micfil->mclk), rate);
> +       ret = clk_set_rate(micfil->mclk, rate * clk_div *
> MICFIL_OSR_DEFAULT * 8);
> +       if (ret)
> +               return ret;
>
>         /* set CICOSR */
>         ret = regmap_update_bits(micfil->regmap, REG_MICFIL_CTRL2,
> @@ -252,11 +220,6 @@ static int fsl_set_clock_params(struct device *dev,
> unsigned int rate)
>         if (ret)
>                 return ret;
>
> -       /* set CLK_DIV */
> -       clk_div = get_clk_div(micfil, rate);
> -       if (clk_div < 0)
> -               ret = -EINVAL;
> -
>         ret = regmap_update_bits(micfil->regmap, REG_MICFIL_CTRL2,
>                                  MICFIL_CTRL2_CLKDIV,
>                                  FIELD_PREP(MICFIL_CTRL2_CLKDIV, clk_div));
> --
> 2.30.2
>
>