Re: [PATCH 4/6] ASoC: rt5670: Fix dac- and adc- vol-tlv values being off by a factor of 10

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

On 6/28/20 10:52 AM, Hans de Goede wrote:
> The adc_vol_tlv volume-control has a range from -17.625 dB to +30 dB,
> not -176.25 dB to + 300 dB. This wrong scale is esp. a problem in userspace

D'oh! nice catch.

> apps which translate the dB scale to a linear scale. With the logarithmic
> dB scale being of by a factor of 10 we loose all precision in the lower
> area of the range when apps translate things to a linear scale.
> 
> E.g. the 0 dB default, which corresponds with a value of 47 of the
> 0 - 127 range for the control, would be shown as 0/100 in alsa-mixer.
> 
> Since the centi-dB values used in the TLV struct cannot represent the
> 0.375 dB step size used by these controls, change the TLV definition
> for them to specify a min and max value instead of min + stepsize.
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>   sound/soc/codecs/rt5670.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/soc/codecs/rt5670.c b/sound/soc/codecs/rt5670.c
> index f21181734170..dfbc0ca38ff7 100644
> --- a/sound/soc/codecs/rt5670.c
> +++ b/sound/soc/codecs/rt5670.c
> @@ -603,9 +603,9 @@ int rt5670_set_jack_detect(struct snd_soc_component *component,
>   EXPORT_SYMBOL_GPL(rt5670_set_jack_detect);
>   
>   static const DECLARE_TLV_DB_SCALE(out_vol_tlv, -4650, 150, 0);
> -static const DECLARE_TLV_DB_SCALE(dac_vol_tlv, -65625, 375, 0);
> +static const DECLARE_TLV_DB_MINMAX(dac_vol_tlv, -6562, 0);
>   static const DECLARE_TLV_DB_SCALE(in_vol_tlv, -3450, 150, 0);
> -static const DECLARE_TLV_DB_SCALE(adc_vol_tlv, -17625, 375, 0);
> +static const DECLARE_TLV_DB_MINMAX(adc_vol_tlv, -1762, 3000);
>   static const DECLARE_TLV_DB_SCALE(adc_bst_tlv, 0, 1200, 0);
>   
>   /* {0, +20, +24, +30, +35, +40, +44, +50, +52} dB */
>