linux-kernel - Re: [PATCH 2/7] ASoC: codecs: lpass-wsa-macro: fix compander volume hack

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Date: Tue, 16 Jan 2024 11:10:21 +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 2/7] ASoC: codecs: lpass-wsa-macro: fix compander volume
 hack

Thanks Johan for this patch,

On 16/01/2024 09:38, 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 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.
> 
This is not a hack, wsa codec requires gain to be programmed after the 
clk is enabled for that particular interpolator.

However I agree with you on programming the gain that is different to 
what user set it.

This is because of unimplemented or half baked implementation of half-db 
feature of gain control in this codec.

We can clean that half baked implementation for now and still continue 
to program the gain values after the clks are enabled.

lets remove spkr_gain_offset and associated code paths in this codec, 
which should fix the issue that you have reported and still do the right 
thing of programming gain after clks are enabled.

thanks,
Srini


> 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 | 10 ----------
>   1 file changed, 10 deletions(-)
> 
> diff --git a/sound/soc/codecs/lpass-wsa-macro.c b/sound/soc/codecs/lpass-wsa-macro.c
> index 7e21cec3c2fb..7de221464d47 100644
> --- a/sound/soc/codecs/lpass-wsa-macro.c
> +++ b/sound/soc/codecs/lpass-wsa-macro.c
> @@ -1583,8 +1583,6 @@ static int wsa_macro_enable_interpolator(struct snd_soc_dapm_widget *w,
>   	struct snd_soc_component *component = snd_soc_dapm_to_component(w->dapm);
>   	u16 gain_reg;
>   	u16 reg;
> -	int val;
> -	int offset_val = 0;
>   	struct wsa_macro *wsa = snd_soc_component_get_drvdata(component);
>   
>   	if (w->shift == WSA_MACRO_COMP1) {
> @@ -1623,11 +1621,7 @@ 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);
>   		break;
> @@ -1654,10 +1648,6 @@ 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);