Re: [PATCH v3 12/16] ASoC: tegra: Fix kcontrol put callback in MVC

[Takashi Iwai <tiwai@suse.de>]

On Thu, 18 Nov 2021 08:07:07 +0100,
Sameer Pujar wrote:
> 
> The kcontrol put callback is expected to return 1 when there is change
> in HW or when the update is acknowledged by driver. This would ensure
> that change notifications are sent to subscribed applications. Filter
> out duplicate updates in MVC driver.
> 
> Fixes: e539891f9687 ("ASoC: tegra: Add Tegra210 based MVC driver")
> Signed-off-by: Sameer Pujar <spujar@nvidia.com>
> Suggested-by: Jaroslav Kysela <perex@perex.cz>
> Suggested-by: Mark Brown <broonie@kernel.org>
> ---
>  sound/soc/tegra/tegra210_mvc.c | 22 ++++++++++++++++++----
>  1 file changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/sound/soc/tegra/tegra210_mvc.c b/sound/soc/tegra/tegra210_mvc.c
> index b7e3170..85b1558 100644
> --- a/sound/soc/tegra/tegra210_mvc.c
> +++ b/sound/soc/tegra/tegra210_mvc.c
> @@ -136,7 +136,7 @@ static int tegra210_mvc_put_mute(struct snd_kcontrol *kcontrol,
>  	struct snd_soc_component *cmpnt = snd_soc_kcontrol_component(kcontrol);
>  	struct tegra210_mvc *mvc = snd_soc_component_get_drvdata(cmpnt);
>  	unsigned int value;
> -	u8 mute_mask;
> +	u8 new_mask, old_mask;
>  	int err;
>  
>  	pm_runtime_get_sync(cmpnt->dev);
> @@ -148,11 +148,19 @@ static int tegra210_mvc_put_mute(struct snd_kcontrol *kcontrol,
>  	if (err < 0)
>  		goto end;
>  
> -	mute_mask = ucontrol->value.integer.value[0];
> +	regmap_read(mvc->regmap, TEGRA210_MVC_CTRL, &value);
> +
> +	old_mask = (value >> TEGRA210_MVC_MUTE_SHIFT) & TEGRA210_MUTE_MASK_EN;
> +	new_mask = ucontrol->value.integer.value[0];
> +
> +	if (new_mask == old_mask) {
> +		err = 0;
> +		goto end;
> +	}
>  
>  	err = regmap_update_bits(mvc->regmap, mc->reg,
>  				 TEGRA210_MVC_MUTE_MASK,
> -				 mute_mask << TEGRA210_MVC_MUTE_SHIFT);
> +				 new_mask << TEGRA210_MVC_MUTE_SHIFT);

I guess this test-and-update procedure can be simplified with
regmap_update_bits_check().


thanks,

Takashi