Hi Daniel,
On 11/10/25 13:42, Daniel Lezcano wrote:
> On 10/16/25 16:21, Laura Nao wrote:
>> Add a guard against zero temp_factor in lvts_raw_to_temp() to prevent
>> division by zero and ensure safe conversion.
>
> Is the temp_factor something else than a ro data statically initialized by the lvts_data structure ?
>
> It is pointless to handle the case where the temp_factor is zero. If we read the temperature the kernel crashes immediately (which means it was not tested).
>
> The temp_factor is an internal value of the driver. If the temp_factor is zero, the driver is buggy and should be fixed.
>
>
That’s right - if temp_factor is zero, that indicates broken platform
data. I propose failing the probe instead of adding a runtime guard,
since this condition should never happen in a valid configuration. This
way, we make the developer aware of the issue early and avoid a kernel
crash at runtime.
I'll send out a v4 to drop the "if (temp_factor == 0)" checks and
replace the warning with an error:
if (!lvts_data->temp_factor)
return dev_err_probe(dev, -EINVAL, "temp_factor should never be zero; check platform data.\n");
Best,
Laura
>> Fixes: 6725a29321e4 ("thermal/drivers/mediatek/lvts_thermal: Make coeff configurable")
>> Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
>> Reviewed-by: Fei Shao <fshao@chromium.org>
>> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> Signed-off-by: Laura Nao <laura.nao@collabora.com>
>> ---
>> drivers/thermal/mediatek/lvts_thermal.c | 12 +++++++++---
>> 1 file changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c
>> index 1c54d0b75b1a..4ef549386add 100644
>> --- a/drivers/thermal/mediatek/lvts_thermal.c
>> +++ b/drivers/thermal/mediatek/lvts_thermal.c
>> @@ -284,11 +284,14 @@ 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)
>> @@ -1346,6 +1349,9 @@ static int lvts_probe(struct platform_device *pdev)
>> if (irq < 0)
>> return irq;
>> + if (!lvts_data->temp_factor)
>> + dev_warn(dev, "temp_factor should never be zero; check platform data.\n");
>> +
>> golden_temp_offset = lvts_data->temp_offset;
>> ret = lvts_domain_init(dev, lvts_td, lvts_data);
> If
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