linux-kernel - Re: [PATCH v3 3/5] ASoC: qcom: sc8280xp: limit speaker volumes

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Date: Fri, 19 Jan 2024 07:37:14 +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 3/5] ASoC: qcom: sc8280xp: limit speaker volumes



On 18/01/2024 16:58, Johan Hovold wrote:
> The UCM configuration for the Lenovo ThinkPad X13s has up until now
> been setting the speaker PA volume to -3 dB when enabling the speakers,
> but this does not prevent the user from increasing the volume further.
> 
> Limit the PA volume to -3 dB in the machine driver to reduce the risk of
> speaker damage until we have active speaker protection in place.
> 
> Note that this will probably need to be generalised using
> machine-specific limits, but a common limit should do for now.
> 
> Cc: stable@...r.kernel.org	# 6.5
> Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
> ---
>   sound/soc/qcom/sc8280xp.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/sound/soc/qcom/sc8280xp.c b/sound/soc/qcom/sc8280xp.c
> index ed4bb551bfbb..a19bfa354af8 100644
> --- a/sound/soc/qcom/sc8280xp.c
> +++ b/sound/soc/qcom/sc8280xp.c
> @@ -32,12 +32,14 @@ static int sc8280xp_snd_init(struct snd_soc_pcm_runtime *rtd)
>   	case WSA_CODEC_DMA_RX_0:
>   	case WSA_CODEC_DMA_RX_1:
>   		/*
> -		 * set limit of 0dB on Digital Volume for Speakers,
> -		 * this can prevent damage of speakers to some extent without
> -		 * active speaker protection
> +		 * Set limit of 0 dB on Digital Volume and -3 dB on PA Volume
> +		 * to reduce the risk of speaker damage until we have active
> +		 * speaker protection in place.

I would prefer a 0dB here instead of -3dB, this could become issue if we 
are testing speakers without any pluseaudio or any software 
amplification. ex: console


>   		 */
>   		snd_soc_limit_volume(card, "WSA_RX0 Digital Volume", 84);
>   		snd_soc_limit_volume(card, "WSA_RX1 Digital Volume", 84);
> +		snd_soc_limit_volume(card, "SpkrLeft PA Volume", 1);
> +		snd_soc_limit_volume(card, "SpkrRight PA Volume", 1)

It would be nice to consider using component->name_prefix here.


thanks,
srini
;

>   		break;
>   	default:
>   		break;