[PATCH 3/9] thermal/drivers/mediatek/lvts: Guard against zero temp_factor in lvts_raw_to_temp

[Chen-Yu Tsai]

On Mon, Jul 21, 2025 at 4:26 PM Laura Nao <laura.nao at collabora.com> wrote:
>
> Add a guard against zero temp_factor in lvts_raw_to_temp() to prevent
> division by zero and ensure safe conversion.
>
> Fixes: 6725a29321e4 ("thermal/drivers/mediatek/lvts_thermal: Make coeff configurable")
> Signed-off-by: Laura Nao <laura.nao at collabora.com>

Code wise,

Reviewed-by: Chen-Yu Tsai <wenst at chromium.org>

However I assume this would only happen with bad platform data? The
factor should _never_ be zero. Maybe also issue a warning in the probe
function?

ChenYu

> ---
>  drivers/thermal/mediatek/lvts_thermal.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c
> index 8d5259b9d03b..b80c2929ae74 100644
> --- a/drivers/thermal/mediatek/lvts_thermal.c
> +++ b/drivers/thermal/mediatek/lvts_thermal.c
> @@ -280,11 +280,14 @@ static int lvts_raw_to_temp(u32 raw_temp, int temp_factor)
>
>  static u32 lvts_temp_to_raw(int temperature, int temp_factor)
>  {
> -       u32 raw_temp = ((s64)(golden_temp_offset - temperature)) << 14;
> +       u32 raw_temp;
>
> -       raw_temp = div_s64(raw_temp, -temp_factor);
> +       if (temp_factor == 0)
> +               return temperature;
>
> -       return raw_temp;
> +       raw_temp = ((s64)(golden_temp_offset - temperature)) << 14;
> +
> +       return div_s64(raw_temp, -temp_factor);
>  }
>
>  static int lvts_get_temp(struct thermal_zone_device *tz, int *temp)
> --
> 2.39.5
>
>