[PATCH] ASoC: max98088: fix ni clock divider calculation

[PATCH] ASoC: max98088: fix ni clock divider calculation

[Marco Felsch]

The ni1/ni2 ratio formula [1] uses the pclk which is the prescaled mclk.
The max98088 datasheet [2] has no such formula but table-12 equals so
we can assume that it is the same for both devices.

While on it make use of DIV_ROUND_CLOSEST_ULL().

[1] https://datasheets.maximintegrated.com/en/ds/MAX98089.pdf; page 86
[2] https://datasheets.maximintegrated.com/en/ds/MAX98088.pdf; page 82

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
Hi,

please be noted that I used the old formatting style which uses spaces
instead of tabs. Therefore checkpatch.pl complains. The whole driver
needs a style adaption but I wanted to keep it for now.

Regards,
  Marco

 sound/soc/codecs/max98088.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/sound/soc/codecs/max98088.c b/sound/soc/codecs/max98088.c
index 4be24e7f51c8..f8e49e45ce33 100644
--- a/sound/soc/codecs/max98088.c
+++ b/sound/soc/codecs/max98088.c
@@ -41,6 +41,7 @@ struct max98088_priv {
 	enum max98088_type devtype;
 	struct max98088_pdata *pdata;
 	struct clk *mclk;
+	unsigned char mclk_prescaler;
 	unsigned int sysclk;
 	struct max98088_cdata dai[2];
 	int eq_textcnt;
@@ -998,13 +999,16 @@ static int max98088_dai1_hw_params(struct snd_pcm_substream *substream,
        /* Configure NI when operating as master */
        if (snd_soc_component_read(component, M98088_REG_14_DAI1_FORMAT)
                & M98088_DAI_MAS) {
+               unsigned long pclk;
+
                if (max98088->sysclk == 0) {
                        dev_err(component->dev, "Invalid system clock frequency\n");
                        return -EINVAL;
                }
                ni = 65536ULL * (rate < 50000 ? 96ULL : 48ULL)
                                * (unsigned long long int)rate;
-               do_div(ni, (unsigned long long int)max98088->sysclk);
+               pclk = DIV_ROUND_CLOSEST(max98088->sysclk, max98088->mclk_prescaler);
+               ni = DIV_ROUND_CLOSEST_ULL(ni, pclk);
                snd_soc_component_write(component, M98088_REG_12_DAI1_CLKCFG_HI,
                        (ni >> 8) & 0x7F);
                snd_soc_component_write(component, M98088_REG_13_DAI1_CLKCFG_LO,
@@ -1065,13 +1069,16 @@ static int max98088_dai2_hw_params(struct snd_pcm_substream *substream,
        /* Configure NI when operating as master */
        if (snd_soc_component_read(component, M98088_REG_1C_DAI2_FORMAT)
                & M98088_DAI_MAS) {
+               unsigned long pclk;
+
                if (max98088->sysclk == 0) {
                        dev_err(component->dev, "Invalid system clock frequency\n");
                        return -EINVAL;
                }
                ni = 65536ULL * (rate < 50000 ? 96ULL : 48ULL)
                                * (unsigned long long int)rate;
-               do_div(ni, (unsigned long long int)max98088->sysclk);
+               pclk = DIV_ROUND_CLOSEST(max98088->sysclk, max98088->mclk_prescaler);
+               ni = DIV_ROUND_CLOSEST_ULL(ni, pclk);
                snd_soc_component_write(component, M98088_REG_1A_DAI2_CLKCFG_HI,
                        (ni >> 8) & 0x7F);
                snd_soc_component_write(component, M98088_REG_1B_DAI2_CLKCFG_LO,
@@ -1113,8 +1120,10 @@ static int max98088_dai_set_sysclk(struct snd_soc_dai *dai,
         */
        if ((freq >= 10000000) && (freq < 20000000)) {
                snd_soc_component_write(component, M98088_REG_10_SYS_CLK, 0x10);
+               max98088->mclk_prescaler = 1;
        } else if ((freq >= 20000000) && (freq < 30000000)) {
                snd_soc_component_write(component, M98088_REG_10_SYS_CLK, 0x20);
+               max98088->mclk_prescaler = 2;
        } else {
                dev_err(component->dev, "Invalid master clock frequency\n");
                return -EINVAL;
-- 
2.29.2

Re: [PATCH] ASoC: max98088: fix ni clock divider calculation

[Mark Brown]

On Fri, 23 Apr 2021 15:54:02 +0200, Marco Felsch wrote:
> The ni1/ni2 ratio formula [1] uses the pclk which is the prescaled mclk.
> The max98088 datasheet [2] has no such formula but table-12 equals so
> we can assume that it is the same for both devices.
> 
> While on it make use of DIV_ROUND_CLOSEST_ULL().
> 
> [1] https://datasheets.maximintegrated.com/en/ds/MAX98089.pdf; page 86
> [2] https://datasheets.maximintegrated.com/en/ds/MAX98088.pdf; page 82

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: max98088: fix ni clock divider calculation
      commit: 6c9762a78c325107dc37d20ee21002b841679209

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark