Re: [PATCH] ASoC: soc-ops: Correct the max value for clamp in soc_mixer_reg_to_ctl()

[Charles Keepax <ckeepax@opensource.cirrus.com>]

On Wed, Dec 17, 2025 at 02:06:23PM +0200, Peter Ujfalusi wrote:
>  sound/soc/soc-ops.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/soc/soc-ops.c b/sound/soc/soc-ops.c
> index ce86978c158d..6a18c56a9746 100644
> --- a/sound/soc/soc-ops.c
> +++ b/sound/soc/soc-ops.c
> @@ -148,7 +148,7 @@ static int soc_mixer_reg_to_ctl(struct soc_mixer_control *mc, unsigned int reg_v
>  	if (mc->sign_bit)
>  		val = sign_extend32(val, mc->sign_bit);
>  
> -	val = clamp(val, mc->min, mc->max);
> +	val = clamp(val, mc->min, mc->min + max);

This won't work, for an SX control it is perfectly valid for
the value read from the register to be smaller than the minimum
value specified in the control.

The minimum value gives the register value that equates to the
smallest possible control value. From there the values increase
but the register field can overflow and end up lower than the
min. I often think of it in terms of a 2's compliement number
with an implicit sign bit.

Thanks,
Charles