linux-kernel - Re: [PATCH v3 1/5] ASoC: codecs: wsa883x: fix PA volume control

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Date: Fri, 19 Jan 2024 07:14:03 +0000
From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To: Johan Hovold <johan+linaro@...nel.org>, Mark Brown <broonie@...nel.org>
Cc: Banajit Goswami <bgoswami@...cinc.com>,
 Liam Girdwood <lgirdwood@...il.com>, Jaroslav Kysela <perex@...ex.cz>,
 Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
 linux-sound@...r.kernel.org, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH v3 1/5] ASoC: codecs: wsa883x: fix PA volume control



On 18/01/2024 16:58, Johan Hovold wrote:
> The PA gain can be set in steps of 1.5 dB from -3 dB to 18 dB, that is,
> in fifteen levels.
> 
> Fix the range of the PA volume control to avoid having the first
> sixteen levels all map to -3 dB.
TBH, we really don't know what unsupported values map to w.r.t dB.

> 
> Note that level 0 (-3 dB) does not mute the PA so the mute flag should
> also not be set.
> 
> Fixes: cdb09e623143 ("ASoC: codecs: wsa883x: add control, dapm widgets and map")
> Cc: stable@...r.kernel.org      # 6.0
> Cc: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
> ---
>   sound/soc/codecs/wsa883x.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/soc/codecs/wsa883x.c b/sound/soc/codecs/wsa883x.c
> index cb83c569e18d..32983ca9afba 100644
> --- a/sound/soc/codecs/wsa883x.c
> +++ b/sound/soc/codecs/wsa883x.c
> @@ -1098,7 +1098,7 @@ static int wsa_dev_mode_put(struct snd_kcontrol *kcontrol,
>   	return 1;
>   }
>   
> -static const DECLARE_TLV_DB_SCALE(pa_gain, -300, 150, -300);
> +static const DECLARE_TLV_DB_SCALE(pa_gain, -300, 150, 0);
>   
>   static int wsa883x_get_swr_port(struct snd_kcontrol *kcontrol,
>   				struct snd_ctl_elem_value *ucontrol)
> @@ -1239,7 +1239,7 @@ static const struct snd_soc_dapm_widget wsa883x_dapm_widgets[] = {
>   
>   static const struct snd_kcontrol_new wsa883x_snd_controls[] = {
>   	SOC_SINGLE_RANGE_TLV("PA Volume", WSA883X_DRE_CTL_1, 1,
> -			     0x0, 0x1f, 1, pa_gain),
> +			     0x1, 0xf, 1, pa_gain),

gain field in register is Bit[5:1], so the max value of 0x1f is correct 
here. However the range of gains that it can actually support is only 0-15.

If we are artificially setting the max value of 0xf here, then somewhere 
we should ensure that Bit[5] is set to zero while programming the gain.

Whatever the mixer control is exposing is clearly reflecting what 
hardware is supporting.

--srini


>   	SOC_ENUM_EXT("WSA MODE", wsa_dev_mode_enum,
>   		     wsa_dev_mode_get, wsa_dev_mode_put),
>   	SOC_SINGLE_EXT("COMP Offset", SND_SOC_NOPM, 0, 4, 0,