On Thu, Apr 7, 2022 at 4:49 PM Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
>
Acked-by: Shengjiu Wang <shengjiu.wang@xxxxxxxxx>
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
>
>
