linux-kernel - Re: [PATCH v3 4/5] ASoC: codecs: lpass-wsa-macro: fix compander volume hack

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Date: Fri, 19 Jan 2024 07:45:45 +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 4/5] ASoC: codecs: lpass-wsa-macro: fix compander
 volume hack



On 18/01/2024 16:58, Johan Hovold wrote:
> The LPASS WSA macro codec driver is updating the digital gain settings
> behind the back of user space on DAPM events if companding has been
> enabled.
> 
> As compander control is exported to user space, this can result in the
> digital gain setting being incremented (or decremented) every time the
> sound server is started and the codec suspended depending on what the
> UCM configuration looks like.
> 
> Soon enough playback will become distorted (or too quiet).
> 
> This is specifically a problem on the Lenovo ThinkPad X13s as this
> bypasses the limit for the digital gain setting that has been set by the
> machine driver.
> 
> Fix this by simply dropping the compander gain offset hack. If someone
> cares about modelling the impact of the compander setting this can
> possibly be done by exporting it as a volume control later.
> 
> Note that the volume registers still need to be written after enabling
> clocks in order for any prior updates to take effect.
> 
> Fixes: 2c4066e5d428 ("ASoC: codecs: lpass-wsa-macro: add dapm widgets and route")
> Cc: stable@...r.kernel.org      # 5.11
> Cc: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
> ---
>   sound/soc/codecs/lpass-wsa-macro.c | 7 -------
>   1 file changed, 7 deletions(-)
> 
> diff --git a/sound/soc/codecs/lpass-wsa-macro.c b/sound/soc/codecs/lpass-wsa-macro.c
> index 7e21cec3c2fb..6ce309980cd1 100644
> --- a/sound/soc/codecs/lpass-wsa-macro.c
> +++ b/sound/soc/codecs/lpass-wsa-macro.c
> @@ -1584,7 +1584,6 @@ static int wsa_macro_enable_interpolator(struct snd_soc_dapm_widget *w,
>   	u16 gain_reg;
>   	u16 reg;
>   	int val;
> -	int offset_val = 0;

TBH, as discussed in my previous review we should just remove 
spkr_gain_offset and associated code path.


--srini

>   	struct wsa_macro *wsa = snd_soc_component_get_drvdata(component);
>   
>   	if (w->shift == WSA_MACRO_COMP1) {
> @@ -1623,10 +1622,8 @@ static int wsa_macro_enable_interpolator(struct snd_soc_dapm_widget *w,
>   					CDC_WSA_RX1_RX_PATH_MIX_SEC0,
>   					CDC_WSA_RX_PGA_HALF_DB_MASK,
>   					CDC_WSA_RX_PGA_HALF_DB_ENABLE);
> -			offset_val = -2;
>   		}
>   		val = snd_soc_component_read(component, gain_reg);
> -		val += offset_val;
>   		snd_soc_component_write(component, gain_reg, val);
>   		wsa_macro_config_ear_spkr_gain(component, wsa,
>   						event, gain_reg);
> @@ -1654,10 +1651,6 @@ static int wsa_macro_enable_interpolator(struct snd_soc_dapm_widget *w,
>   					CDC_WSA_RX1_RX_PATH_MIX_SEC0,
>   					CDC_WSA_RX_PGA_HALF_DB_MASK,
>   					CDC_WSA_RX_PGA_HALF_DB_DISABLE);
> -			offset_val = 2;
> -			val = snd_soc_component_read(component, gain_reg);
> -			val += offset_val;
> -			snd_soc_component_write(component, gain_reg, val);
>   		}
>   		wsa_macro_config_ear_spkr_gain(component, wsa,
>   						event, gain_reg);