Re: [PATCH v9,4/7] thermal: mediatek: Add LVTS driver for mt8192 thermal zones

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 15/09/22 18:58, Balsam CHIHI ha scritto:
> Hi Angelo,
> 
>>> +static int soc_temp_lvts_read_temp(void *data, int *temperature)
>>> +{
>>> +     struct soc_temp_tz *lvts_tz = (struct soc_temp_tz *)data;
>>> +     struct lvts_data *lvts_data = lvts_tz->lvts_data;
>>> +     struct device *dev = lvts_data->dev;
>>> +     unsigned int msr_raw;
>>> +
>>> +     msr_raw = readl(lvts_data->reg[lvts_tz->id]) & MRS_RAW_MASK;
>>> +     if (msr_raw == 0) {
>>> +             /* Prevents a false critical temperature trap */
>>> +             *temperature = 0;
>>> +             dev_dbg(dev, "LVTS not yet ready\n");
>>
>> ...and you're not returning an error code, despite this function was called
>> while LVTS is still not ready? :-)
>>
> 
> if I add "return -ENAVAIL;" here, I will get the following errors on boot :
> [    0.292094] thermal thermal_zone0: failed to read out thermal zone (-119)
> [    0.293019] thermal thermal_zone1: failed to read out thermal zone (-119)
> [    0.294158] thermal thermal_zone6: failed to read out thermal zone (-119)
> [    0.295697] thermal thermal_zone9: failed to read out thermal zone (-119)
> [    0.296600] thermal thermal_zone10: failed to read out thermal zone (-119)
> [    0.297698] thermal thermal_zone15: failed to read out thermal zone (-119)
> [    0.298625] thermal thermal_zone16: failed to read out thermal zone (-119)
> 
> I just preferred : *temperature = 0; to avoid a false critical temperature trap,
> and "return 0;" to suppress these errors.
> After that (first read at boot when LVTS is not fully ready),
> "msr_raw" will be always != 0.
> And I did not want to add a "delay" or a "sleep".
> Please let me know if you have any suggestions that could fix it in a
> better way.
> 

It's the wrong error number. You have to return -EAGAIN :-)

>>> +
>>> +     } else
>>> +             *temperature = lvts_raw_to_temp(&lvts_data->coeff, msr_raw);
>>> +
>>> +     return 0;
>>> +}
> 
> Best regards,
> Balsam